Extra-Articular Injuries of the Knee

Ovid: Rockwood and Wilkins Fractures in Children

Editors: Beaty, James H.; Kasser, James R.
Title: Rockwood and Wilkins Fractures in Children, 7th Edition
> Table of Contents > Section Four – Lower Extremity > 23 – Extra-Articular Injuries of the Knee

Extra-Articular Injuries of the Knee
Charles T. Price
Jose Herrera-Soto
Extra-articular injuries of the knee principally involve
the patella and the physes of the distal femur and proximal tibia.
Great force generally is required to disrupt these structures in
children and adolescents. This leads to increased risks of associated
injuries and growth arrest. Neurovascular structures are also at
increased risk because of close proximity to the distal femur and
proximal tibia. Growth disturbances may have severe consequences due to
rapid growth around the knee. Accurate reduction is critical for proper
knee function. Therefore, careful assessment and anatomic alignment
with stable fixation are generally recommended for extra-articular
injuries of the knee. Parents should be advised that x-ray follow-up is
essential for early detection and treatment of growth disturbances from
these injuries.
Distal femoral physeal injuries are uncommon, accounting for fewer than 2% of all physeal injuries.78,96,124 However, complications requiring additional surgery occur after approximately 40% to 60% of these injuries.3,44,53,71,89,133,154,159 The most common complication is growth disturbance with angular deformity


and/or shortening; this has been reported in 35% to 50% of patients regardless of anatomic reduction.3,44,53,71,89,154,159
The prognosis is better for very young children and nondisplaced
fractures, but complications are frequent and may occur with any distal
femoral physeal injury. Careful assessment, anatomic reduction, and
secure immobilization or fixation are recommended for most injuries.
Follow-up for many months is recommended for early detection of growth

Mechanism of Injury
In the days of horse-drawn wagons, this injury was
termed “wagon-wheel injury” or “cartwheel injury” because it occurred
when boys attempted to jump onto a moving wagon and the leg became
entrapped between the spokes of the moving wheel. This often led to
amputation because of associated neurovascular trauma.70 Today, most distal femoral fracture separations are the result of motor vehicle or sports-related trauma (Table 23-1).3
Underlying conditions such as neuromuscular disorders, joint
contractures, difficult deliveries, or nutritional deficiencies may
predispose some children to separation of the distal femoral epiphysis.4,5,7,94,121
The principles of management for pathologic fractures may vary from
those for fractures in otherwise healthy children because severe trauma
is generally necessary to separate the distal femoral epiphysis in
healthy children. This is especially true between the ages of 2 to 11
years. Less force is required for physeal disruption in infants and
adolescents.133 Child abuse should
be suspected in infants and toddlers when a small peripheral
metaphyseal fragment of bone, also called a “corner fracture,” is
identified in association with a nondisplaced distal femoral epiphyseal
fracture (Fig 23-1).87
In the adolescent age group, valgus and torsional injury during sports
are a common cause of distal femoral epiphyseal separation (Fig 23-2).
The most common mechanism of injury is a varus or valgus
stress across the knee joint. In skeletally mature individuals, this
mechanism of injury can cause ligamentous disruption because ligaments
commonly fail before bone fails when a bending stress is applied across
the knee joint (Fig. 23-3A). However, loading
to failure across the immature knee is more likely to lead to physeal
failure due to tensile stresses that are transmitted through the
ligaments to the adjacent physis (Fig. 23-3B).45
Bending creates tension on one side of the physis and compression on
the opposite side. This leads to disruption of the periosteum and
perichondrial ring on the tension side, followed by a fracture plane
that begins in the hypertrophic zone and proceeds in an irregular
manner through the physis.21
Salter-Harris type I fractures generally extend through the
hypertrophic zone and the zone of provisional calcification without
traversing the germinal layers. Salter-Harris type II fractures exit
through the


metaphysis with a spike of metaphyseal bone attached to the epiphysis on the compression side (Thurstan-Holland fragment) (Fig. 23-4A).
Salter-Harris type III and IV fractures cross the entire physis
vertically and enter the joint through the articular cartilage. Bright
et al.21 demonstrated that male and
prepubescent animals are less resistant to epiphyseal separation when
various loads are applied, and that the growth plate is also weakest in
torsion. Direction of force determines direction of displacement of the
distal fragment. When the knee is hyperextended, the distal fragment is
displaced anteriorly. Pure compression force also can cause distal
femoral physeal damage (Salter-Harris type V). Premature growth arrest
has been reported after pure compression injuries and also in
association with nonphyseal fractures of the femoral and tibial shafts.10,66,107,142


Salter-Harris type III fractures of the distal medial femoral condyle
result from the same mechanism of injury that produces medial
collateral and cruciate ligament disruption in skeletally mature
patients. The pull of the medial collateral ligament (MCL) results in
condylar separation instead of MCL disruption. Salter-Harris type III
fractures of the medial femoral condyle are frequently associated with
cruciate ligament injuries.22,98,130,162
This pattern of fracture occurs near skeletal maturity when the central
portion of the distal femoral physis begins to close before the medial
and lateral physis. Thus the mechanism of this injury is similar to
that of the juvenile Tillaux fracture in the adolescent ankle.98

TABLE 23-1 Mechanism of Injury in Clinical Reviews of Separation of the Distal Femoral Epiphysis






Sports injury





81 (49%)

Hit by automobile





42 (25%)






19 (12%)

Auto accident




9 (5%)





15 (9%)

* Neer CS II. Separation of the lower femoral epiphyses. Am J Surg 1960;99:756-761.

Bassett FH III, Goldner JL. Fractures involving the distal femoral epiphyseal growth line. South Med J 1962;55:545-557.

Roberts JM. Fracture separation of the distal femoral epiphysis. J Bone Joint Surg Am 1973;55A:1324.

** Stephens
DC, Louis DS, Louis E. Traumatic separation of the distal femoral
epiphyseal cartilage plate. J Bone Joint Surg Am 1974;56:1383-1390.

Lateral radiograph of a swollen knee in a 3-month-old girl who
reportedly fell out of her crib 8 days earlier. Subperiosteal
ossification along the distal femoral shaft indicates separation of the
distal femoral epiphysis. Note evidence of fracture-separation of the
proximal tibial epiphysis as well. Final diagnosis: abused child.
FIGURE 23-2 Valgus and torsional stress across the knee may cause a ligament injury or physeal separation.
FIGURE 23-3 A. In a skeletally mature patient with closed physis, tensile failure usually occurs across the ligament. B.
In a skeletally immature patient with open physis, failure usually
occurs across the physis. (Reprinted with permission from Skaggs DL,
Flynn JF. Trauma about the knee, tibia, and foot. In Skaggs DL, Flynn
JF, eds. Staying out of Trouble in Pediatric Orthopaedics.
Philadelphia: Lippincott Williams & Wilkins; 2006.)
FIGURE 23-4 A.
In a Salter-Harris type II fracture, the side where the fracture
occurred through the physis fails in tension, with disruption of the
periosteum. The side of the fracture with the Thurstan-Holland fragment
failed in compression, with the periosteum usually intact. The intact
periosteum can be used for fracture reduction. B. With fracture reduction, the periosteum may become interposed within the fracture site, preventing an anatomic reduction
Signs and Symptoms
The clinical diagnosis of distal femoral epiphyseal
separation is usually obvious, but minor degrees of displacement may
require careful examination and x-ray interpretation. The patient is in
pain and cannot walk or bear weight on the injured limb immediately
after sustaining a displaced separation of the distal femoral
epiphysis. Most often, these injuries result from significant force
causing visible malalignment of the limb, swelling, and/or ecchymosis
that make the diagnosis of a fracture obvious (Fig. 23-5).
Abrasion or laceration of the overlying soft tissues may be a clue to
the mechanism of injury or to an open fracture. More swelling and
prominence may be noted on the side that opened in tension. On this
side, the periosteum is usually ruptured and the metaphyseal fragment
may buttonhole through the quadriceps muscle. On the opposite side, in
the direction of displacement, the periosteum is usually intact and may
help guide reduction. If a fracture is suspected, it is better to
obtain x-rays before any manipulation. When muscle spasm can be
relaxed, instability just above the knee joint may be felt. Fracture
crepitus sometimes may be absent if the periosteum is interposed
between the metaphysis and the epiphysis. Whenever epiphyseal
separation is suspected, careful neurovascular examination of the lower
leg and foot should be performed, including pulses, color, temperature,
and motor and sensory status. The extremity may become cyanotic if
venous return is impaired. The use of Doppler ultrasound may be helpful
in evaluating circulation distal to the injury. Compartmental pressure
recordings should be obtained if there are clinical findings of
compartment syndrome. Extravasation of blood into the soft tissues of
the distal thigh and popliteal fossa produces ecchymosis that may
become more apparent within 72 hours after injury.
FIGURE 23-5 A.
Completely displaced Salter-Harris type II fracture of the distal femur
in a 6-year-old girl whose foot was on the back of the driver’s
headrest when the automobile in which she was riding was involved in an
accident. B. Ecchymosis in the popliteal
fossa and anterior displacement of the distal femur are evident.
Clinical examination revealed absence of peroneal nerve function and a
cold, pulseless foot.
Occasionally, with a nondisplaced separation the patient
is able to bear some weight on the limb and it may be possible to
localize tenderness to the level of the physis rather than the joint
line where ligament disruptions are more frequent. Abnormal laxity may
be perceived on clinical examination but can be the result of physeal
instability rather than a ligamentous tear. In an adolescent or child
with a knee injury and swelling, occult physeal instability should be
suspected. Stress x-rays or magnetic resonance imaging (MRI) may be
indicated when doubt exists.98,147,162
MRI may be tolerated better by patients and provides the advantage of
evaluating possible ligament injuries. Ultrasonography may be used as a
diagnostic tool in infants and toddlers.68
Associated Injuries
Ligamentous Injuries
Symptomatic knee joint instability may persist after the epiphyseal separation has healed. This finding at follow-up implies


concomitant injury to knee ligaments that may be present at the time of
initial management of the epiphyseal separation. Bertin and Goble15
found that six of 16 patients seen in follow-up for distal femoral
physeal fractures had ligamentous instability. A review of 151 children
with distal femoral physeal fractures found symptomatic knee
ligamentous laxity in 12 patients (8%).44 Salter-Harris type III fractures of the medial femoral condyle are frequently associated with cruciate ligament injuries.22,98,130,162
For this reason, an MRI, instead of stress x-rays, may provide more
information about Salter-Harris type III fractures to help diagnose
ligamentous injury. Early diagnosis of injury to the ligaments or
menisci can facilitate early management.15
In general, fracture stabilization is the first step with ligament
reconstruction or meniscal repair done after physeal healing. If there
is no meniscal injury, a rehabilitation program is indicated initially.
If there is a reparable meniscal tear, cruciate reconstruction can be
done at the time of meniscal repair depending on the patient’s age and
activity level.

FIGURE 23-5 (continued)
The fracture was irreducible by closed methods and required open
reduction, internal fixation, and repair of a popliteal artery
laceration. C,D. Incomplete reduction
Salter-Harris type II fracture in a 6-year-old girl with 25 degrees of
posterior angulation and abundant callus formation. E,F.
Four years later, remodeling has occurred and no growth disturbance is
noted. Results such as this cannot be relied upon, and early anatomic
reduction is recommended.

Vascular Impairment
Vascular injuries are uncommon with this fracture, with most series reporting no vascular injuries.44,89,133,159 However, compartment syndrome has been reported and should be suspected when pain is severe.44
Intimal tear and thrombosis in the popliteal artery may be caused by
trauma from the distal end of the metaphysis when the epiphysis is
displaced anteriorly during a hyperextension injury.11,44,140
In patients with known vascular injury, vascular repair should be
carried out immediately after fracture stabilization. If vascular
impingement occurs but is relieved by prompt reduction of the displaced
epiphysis, the patient should still be closely observed for the classic
signs of vascular impairment or compartment syndrome. Arteriography and
vascular consultation should be considered when perfusion is less than
normal. If there is an associated fracture of the pelvis or femoral
shaft, arteriography may be necessary to localize the vascular injury.
Vascular impairment may develop slowly from increasing compartmental
pressure. If the patient has inordinate persistent pain or a cool and
pale foot, a femoral arteriogram and compartment pressure measurement
should be considered even when peripheral pulses are present.
FIGURE 23-6 The Salter-Harris classification of fractures involving the distal femoral physis.
For known vascular injuries associated with fracture, it
is unclear whether vascular repair or fracture stabilization should be
carried out first.20,26,153
Most distal femoral epiphyseal separations can be stabilized rapidly
with screw or pin fixation before vascular repair. Ischemia time may be
increased when prolonged fracture stabilization is performed first, but
vascular repair is at risk for avulsion when it is done before
manipulations necessary for fracture stabilization.
Peroneal Nerve Injury
The peroneal nerve is the only nerve injured with any frequency in this type of fracture.44
It may be stretched by anterior or medial displacement of the epiphysis
with resulting neurapraxia. Spontaneous recovery can be expected
following reduction and fixation of the fracture.44,149
The exception to this is a transected nerve in association with an open
injury, which can be treated with repair or grafting. Persistent
neurologic deficit after 6 months warrants electromyographic
examination. If the conduction time is prolonged and fibrillation or
denervation is present in distal muscles, exploration and microneural
reanastomosis or resection of any neuroma may be indicated.
Diagnosis and Classification
Separations of the distal femoral epiphysis have been
classified according to the pattern of fracture, the direction and
magnitude of displacement, and the age of the patient. The
Salter-Harris classification140 is
useful for description and treatment planning. Classification by
direction and degree of displacement may help plan the reduction and
predict the risk of complications.3,71 Classification by age may help identify the mechanism of injury and the implications for growth disturbance.
Classification by Fracture Pattern
The Salter-Harris classification is useful for fracture description and treatment planning (Fig. 23-6). This classification is also a good indicator of the mechanism of injury.36 Posttraumatic growth arrest is common after all types of distal femoral epiphyseal fractures89,154 and opinions vary as to whether or not this classification system helps predict potential complications including


growth disturbance.3,36,44,89,133
Salter-Harris type I and II fractures in other areas of the body
usually have a low risk of growth arrest, even minimally displaced
Salter-Harris type I and II fractures of the distal femur should be
followed closely for physeal injury. Growth disturbance is uncommon in
patients younger than 2 years of age,133 but these fractures in older children lead to growth arrest in 40% to 50% of patients.71,133

The Salter-Harris type I pattern is a separation through
the distal femoral physis, without fracture through the adjacent
epiphysis or metaphysis (Fig. 23-7). It occurs
in infants as a birth injury or abuse and in adolescents, often as a
nondisplaced separation. This type of fracture may go undetected.
Sometimes, the diagnosis is made only in retrospect, when subperiosteal
new bone formation occurs along the adjacent metaphysis. When
displacement is present before the age of 2 years, it is usually in the
sagittal plane.
FIGURE 23-7 A. Salter-Harris type I fracture of the distal femur in an 8-year-old. B. Lateral view shows hyperextension. C. Fixation following closed reduction under general anesthesia. Note that pins are widely separated at the fracture site. D. Lateral view of fixation.
The Salter-Harris type II pattern is the most common type of separation of the distal femoral epiphysis (Fig. 23-8).
This pattern is characterized by an oblique extension of the fracture
across one corner of the adjacent metaphysis. The metaphyseal


that remains attached to the epiphysis is called the Thurston-Holland
fragment. Displacement is usually toward the side of the metaphyseal

FIGURE 23-8 A. Salter-Harris type II fracture in a 12-year-old boy. B. Lateral view. C. AP view after closed reduction and fixation. Note that screws function in compression with threads across fracture line. D. Lateral view. E.
Six months after injury, this plain radiograph and clinical picture was
suspicious of increased valgus. Note that the radiograph is not
centered on the distal physis, and thus the physis is difficult to
The Salter-Harris type III injury is a separation of a
portion of the epiphysis, with a vertical fracture line extending from
the physis down to or through the articular surface of the epiphysis (Fig. 23-9).
Salter-Harris type III injuries of the distal femur usually involve the
medial condyle. These injuries are produced by valgus stress during
sports activity and may have an associated injury to the cruciate
ligaments.22,125 Nondisplaced fractures may only be detectable with a stress x-ray or MRI.98 McKissick et al.98
noted that the Salter-Harris type III fracture pattern may be related
to the sequence of closure of the distal femoral physis, similar to a
juvenile Tillaux fracture of the distal tibia.98
Occasionally, a type III fracture may be in the coronal plane


of the condyle similar to the “Hoffa fracture” of the posterior condyle seen in adults.85,110 This fracture is very difficult to diagnose with standard x-rays.138

FIGURE 23-9 A.
Salter-Harris type III fracture-separation of the distal femur. Note
the vertical fracture line extending from the physis distally into the
intercondylar notch with displacement. B.
After reduction and fixation with two compression screws extending
transversely across the epiphyseal fragments. Note closure and healing
of the vertical fracture line in the epiphysis, with restoration of the
articular surface.
Salter-Harris type IV injuries of the distal femur are
uncommon. The fracture line extends vertically through the metaphyseal
cortex, across the physis, and exits through the articular surface of
the epiphysis (Fig. 23-10). Even slight
displacement of a Salter-Harris type IV fracture may produce a bony
bridge from the displaced epiphysis to the metaphysis. Therefore,
anatomic reduction and internal fixation are essential for type IV
FIGURE 23-10 A. Comminuted Salter-Harris type IV fracture of the distal femur in a 14-year-old boy involved in a motor vehicle accident. B. Six months after open reduction and internal fixation with cannulated screws in the metaphysis and epiphysis

Salter-Harris type V injury occurs when the physis is
crushed without displacement. This injury is rare and often diagnosed
retrospectively when growth disturbance is observed following an injury
to the knee.148 When a type V injury
is suspected, an MRI may identify bone contusion on both sides of the
growth plate, suggesting compression damage of the growth plate.142
Other patterns of epiphyseal injury can occur that do
not fit into the original Salter-Harris classification. A type VI
injury has been proposed and is occasionally identified following
femoral epiphyseal trauma.113,131
A type VI injury is an avulsion of the periphery of the physis with a
fragment of metaphyseal and epiphyseal bone attached. This small
fragment, including a portion of the perichondrium and underlying bone,
may be torn off when the proximal attachment of the collateral ligament
is avulsed.
Classification by Displacement
Several authors have evaluated magnitude and direction of displacement to predict final outcome.3,71,89,159 Direction of displacement may guide treatment but does not predict the frequency of poor outcomes in general.3,71,149
Anterior displacement of the epiphysis results from hyperextension of
the knee and has an increased risk of neurovascular damage,36,149 but direction
of displacement does not correlate with other complications such as
angular deformity, growth disturbance, or loss of motion. In contrast, severity of displacement does predict final outcome and complications.3,71,159
Amount of displacement has been evaluated by several different methods,
but displacement of more than one third of bone width correlates with
higherenergy trauma and more frequent complications.3,71,89,159
Metaphyseal comminution which may indicate higher-energy trauma has
also been correlated with an increased risk of complications.71
Classification According to Age
Age at time of injury correlates with frequency and severity of complications.133
Distal femoral epiphyseal fractures in children aged 2 to 11 years are
caused by more severe trauma and have the worst prognosis.44,133
In adolescents, low-energy sports injuries are the most frequent cause
of epiphyseal separation. Because adolescents have little growth,
remaining severe growth retardation is uncommon. Separations of the
distal femoral epiphysis before the age of 2 years generally have
satisfactory outcomes,95,133,159 possibly because epiphyseal undulations and the central peak are not as prominent in infants as in older children (Fig. 23-11A).111
In juveniles and adolescents, the fracture may pass through the central
prominence and lead to central growth arrest due to interference with
vascularity in this region or due to the fracture plane exiting and
re-entering the central physis (Fig.23-11B).111,133,151
FIGURE 23-11 A. Distal femoral physeal separation prior to the age of 2 years may not disrupt growth because the physis is flat. B.
After the age of 2 years, a central ridge and four quadrants of
undulation develop in the distal femur. Fractures in this age group are
more likely to cross multiple planes of bone and cartilage.
Because the physis normally is radiolucent, injury is
diagnosed by widening, displacement of the epiphysis, or adjacent bony
disruption; however, a nondisplaced Salter-Harris type I or III
fracture without separation can be easily overlooked.7,138,162 Oblique views of the distal femur may reveal an occult fracture through the epiphysis or metaphysis (Table 23-2).
It has been suggested that stress views should be considered if
multiple plain films are negative in a patient with an effusion or
tenderness localized to the physis;147
however, when a fracture is not visible on standard x-rays,
immobilization in a cast may be preferable because stress x-rays may be
painful or further disrupt alignment. Also, there is no urgent reason
to repair ligamentous injuries, so 2 weeks of immobilization will
usually define the injury as accurately as stress radiographs.151
Another option for early diagnosis of occult injury is MRI, which
should be diagnostic for fracture and/or associated soft tissue
injuries.98 A computed tomography
(CT) scan may be preferable for evaluating fractures with metaphyseal
comminution or determining fracture geometry for fixation purposes.
Standard x-rays are sufficient for initial evaluation of
most distal femoral epiphyseal fractures. The magnitude and direction
of displacement along with the fracture pattern are used to guide
treatment. Medial or lateral displacement or a vertical epiphyseal
fracture line is best seen on an anteroposterior (AP) view. This view
allows differentiation of Salter-Harris types III and IV injuries from
other types. Minor degrees of displacement may be difficult to measure
on plain films unless the x-ray projection is precisely in line with
the plane of fracture. Even small amounts of displacement are
significant.71,89 Anterior or posterior displacement of the epiphysis is best appreciated on the


lateral projection. The anteriorly displaced epiphysis is usually
tilted so that the distal articular surface faces anteriorly
(hyperextension). The posteriorly displaced epiphysis is rotated so
that the distal articular surface faces the popliteal fossa. Separation
of the distal femoral epiphysis in an infant is difficult to see on
initial x-rays unless there is displacement because only the center of
the epiphysis is ossified at birth. This ossification center should be
in line with the axis of the femoral shaft on both AP and lateral
views. Comparison views of the opposite knee may be helpful.
Ultrasonography, arthrography, or MRI of the knee may help to identify
a separation of the relatively unossified femoral epiphysis.69,173

TABLE 23-2 Imaging Studies in the Evaluation of Distal Femoral Physeal Fractures




Standard radiographs

First study, often sufficient.

May miss nondisplaced Salter-Harris type I or III fractures or underestimate fracture displacement.

CT scan

Best defines fracture pattern and amount of displacement.

Useful for planning surgery, especially for metaphyseal comminution.

Poor cartilage visualization.

Less useful than MRI in evaluating for occult Salter-Harris type I or III fractures.


Evaluation of occult Salter-Harris type I fracture, especially in infants with little epiphyseal ossification.

Identifies associated soft tissue injuries, especially with Salter-Harris type III fractures.

Availability, cost, duration of procedure.

Fracture geometry less clear than with CT scans.

Stress views

Differentiate occult Salter-Harris fracture from ligament injury.

Painful, muscle spasm may not permit opening of fracture if patient awake. Unclear that study changes initial treatment.

Contralateral radiographs

Infants, or to assess physeal width.

Follow-up to compare growth.

Usually not helpful in acute fractures.

Ultrasonography arthrography

Infants to assess swelling and displacement of epiphysis.

Not useful after infancy.

MRI may be helpful for accurate diagnosis of fracture in
adolescent knee injuries. In a review of MRI scans of 315 adolescents
with traumatic knee injuries, physeal injuries of the distal femur were
diagnosed in seven patients and of the proximal tibia in two patients.
Plain films available on eight patients showed signs of fracture in
seven patients, but the fracture was clearly delineated in only one
patient.32 For evaluation of the
physis with MRI, fat-suppressed three-dimensional spoiled
gradient-recalled echo sequences reportedly provide the best
Impending growth disturbance can be identified early with MRI41,46 and MR or CT imaging can be useful to evaluate growth arrest before excision of a bony bar.41,88
Surgical and Applied Anatomy
The epiphysis of the distal femur is the first epiphysis
to ossify and is present at birth. From birth to skeletal maturity, the
distal femoral physis contributes 70% of the growth of the femur and
37% of the growth of the lower extremity. The annual rate of growth is
approximately three eighths of an inch or 9 to 10 mm. The growth ceases
at a mean skeletal age of 14 years in girls and 16 years in boys.2,172
Physeal Anatomy
At birth, the distal femoral physis is flat. With maturation, the physis assumes an undulating and convoluted shape.86
An intercondylar groove develops along with medial and lateral sulci.
This divides the physis into four quadrants of concave configuration
that match the four convex surfaces of the distal femoral metaphysis.
This complex geometry may help resist shear and torsional forces and
also the large cross-sectional area of the distal femoral physis
contributes to stability. The perichondral ring and ligamentous
structures provide additional resistance to disruption of the physis,
but these structures become thinner during the adolescent growth period.30,103
Thus, substantial force is required to disrupt the distal femoral
physis in juveniles, but less force may produce separation in infants
and adolescents. When fractures do occur in the distal femur, the
irregular configuration of the physis may predispose to crack lines
that extend through multiple regions of the physis regardless of
fracture type (see Fig. 23-11).133
During reduction of displaced fractures, epiphyseal ridges may grind
against the metaphyseal projections and damage germinal cells. Gentle,
anatomic reduction is recommended, but reduction under general
anesthesia does not correlate with reduced risk of growth disturbance.159 Salter-Harris type I fractures generally extend through the hypertrophic


zone and the zone of provisional calcification without traversing the
germinal layers. Salter-Harris type II fractures exit through the
metaphysis with a spike of metaphyseal bone attached to the epiphysis
on the compression side (Thurston-Holland fragment) (see Fig. 23-4A).
In any type of epiphyseal fracture, a flap of torn periosteum may
become interposed between the fragments and prevent reduction (see Fig. 23-4B). Salter-Harris types III and IV fractures cross the entire physis vertically and enter the joint through articular cartilage.

Bony Anatomy
Immediately above the medial border of the medial
condyle, the metaphysis of the distal femur widens sharply to the
adductor tubercle. In contrast, the metaphysis flares minimally on the
lateral side to produce the lateral epicondyle. The mechanical axis of
the femur is formed by a line between the centers of the hip and knee
joints (Fig. 23-12). A line tangential to the
distal surfaces of the two condyles (the joint line) is in
approximately 3 degrees of valgus relative to the mechanical axis. The
longitudinal axis of the diaphysis of the femur inclines medially in a
distal direction at an angle of 6 degrees relative to the mechanical
axis and an angle of 9 degrees relative to the distal articular plane.67
FIGURE 23-12
The mechanical and anatomic axis of the lower extremity. Note that the
knee joint is in a mean of 3 degrees of valgus. The femoral shaft
intersects the transverse plane of the distal femoral articular surface
at an angle of 87 degrees.
A large part of the surface of the distal femoral
epiphysis is covered by cartilage for articulation with the proximal
tibia and patella. The anterior or patellar surface has a shallow
midline concavity to accommodate the longitudinal ridge on the
undersurface of the patella. The distal or tibial surface of each
condyle extends on either side of the intercondylar notch far around
onto the posterior surface. Here, the articular cartilage nearly
reaches the posterior margin of the physis.
Soft Tissue Anatomy
The distal femoral physis is completely extra-articular.
Anteriorly and posteriorly, the synovial membrane and joint capsule of
the knee attach to the femoral epiphysis close to the distal femoral
physis. Anteriorly, the suprapatellar pouch balloons proximally over
the anterior surface of the metaphysis. On the medial and lateral
surfaces of the epiphysis, the proximal attachment of the synovium and
capsule is below the physis and separated from the physis by the
insertions of the collateral ligaments. The strong posterior capsule
and all major supporting ligaments of the knee are attached to the
epiphysis of the femur distal to the physis. Both cruciate ligaments
originate in the upward-sloping roof of the intercondylar notch distal
to the physis. Compression and tension forces can be transmitted across
the extended knee to the epiphysis of the femur by taut ligaments.
The medial and lateral head of the gastrocnemius
originate from the distal femur, proximal to the joint capsule. Thus,
fractures due to forces transmitted through the muscles and tendons do
not seem to be as much of a factor as forces transmitted through the
ligaments and capsule.
Neurovascular Anatomy
The popliteal artery is separated from the posterior
surface of the distal femur by only a thin layer of fat. Directly
proximal to the femoral condyles, the superior geniculate arteries pass
medially and laterally to lie between the femoral metaphysis and the
overlying muscles. As the popliteal artery continues distally, it lies
on the posterior capsule of the knee joint between the femoral
condyles. At this level, the middle geniculate artery branches
anteriorly to enter the posterior aspect of the distal femoral
epiphysis. The popliteal artery and its branches are vulnerable to
injury from the distal femoral metaphysis at the time of hyperextension
The sciatic nerve divides into the peroneal and tibial
nerves proximal to the popliteal space. The peroneal nerve descends
posteriorly between the biceps femoris muscle and the lateral head of
the gastrocnemius muscle to a point just distal to the head of the
fibula. Thus, there is interposed muscle protecting the nerve from the
potentially sharp edges of a physeal fracture. The nerve is subject to
stretch if the distal femoral epiphysis is tilted into varus or rotated
The distal femoral epiphysis receives its blood supply
from a rich anastomosis of vessels. It is unlikely that the distal
femoral epiphysis would be completely shorn of its blood supply unless
an articular fragment is extruded or completely stripped of its


tissue attachments. Clinically, osteonecrosis of the epiphysis is not a
commonly recognized sequela of distal femoral epiphyseal fractures.

Current Treatment Options
The most common complication of distal femoral physeal
fractures is growth disturbance with angular deformity and/or limb
length discrepancy.3,36,44,89
Ligamentous instability and loss of knee motion are also frequently
reported long-term sequelae. Completely nondisplaced fractures can be
managed with cast immobilization, but close follow-up is recommended to
detect and treat any displacement (Table 23-3).3,71
Closed reduction can be attempted for Salter-Harris types I and II
fractures, but subsequent displacement is frequent when patients are
immobilized in long-leg casts without internal fixation.44,53,159 Anything less than anatomic reduction increases the risk of growth disturbance.44,51,89,133 Fracture remodeling is unpredictable when small degrees of malalignment are accepted in patients older than 2 years of age.133
For these reasons, anatomic reduction, stable fixation, and careful
follow-up are the basis of treatment of physeal fractures of the distal
Closed Reduction and Cast Immobilization
Nondisplaced Fractures (≤2 mm). Nondisplaced fractures
of the distal femoral epiphysis are uncommon. Outcomes with cast
immobilization are usually satisfactory,89,159 but displacement can occur even with cast immobilization.3,44
A well-molded long-leg cast is applied with the knee in approximately
15 degrees to 20 degrees of flexion with the intact periosteal hinge
tightened. Thus, if the metaphyseal fragment of a nondisplaced
Salter-Harris type II separation is on the lateral side of the
metaphysis, the cast is applied with three-point molding into slight
varus. Alternative methods of immobilization include a posterior
splint, cylinder cast from proximal thigh to ankle, and a single hip
spica cast. The more secure form of immobilization or internal fixation
should be considered if the patient is obese or potentially unreliable.
TABLE 23-3 Methods of Treatment for Distal Femoral Physeal Fractures





Closed reduction and immobilization

Avoids anesthesia

High risk of loss of reduction

Nondisplaced, stable fractures

Closed reduction and screw fixation

Minimal dissection

Only in reducible fractures

Reducible Salter-Harris type II fractures

Nondisplaced Salter-Harris type III and IV fractures

Closed reduction and smooth pinning

Minimal dissection

Pins may lead to joint infection or require later removal

Reducible Salter-Harris type I fractures, and Salter-Harris type II fractures with small metaphyseal fragment

Open reduction and screws and/or pins

Anatomic reduction


Irreducible Salter-Harris type I and II fractures, displaced Salter-Harris type III and IV fractures

External fixation

Allows soft tissue access

Pin site (joint) infection

Severe soft tissue injury

Rigid plate crossing physis

Rigid fixation

Can stop future growth when spans physis

Adolescents near the end of growth

Severe injuries with severe disturbance inevitable

Possible temporary fixation with extraperiosteal locked plating removed soon after union

Displaced Fractures (>2 mm). Displaced Salter-Harris
types III and IV fractures are managed by open reduction and stable
fixation, which are discussed later in this section. Closed reduction
can be attempted up to 10 days after injury for Salter-Harris types I
and II fractures, but these fractures are inherently unstable when
immobilized without restricting motion of the hip. Anatomic reduction
is recommended, with less than a 2-mm gap following reduction.44,71 Redisplacement in long-leg casts has been reported in 30% to 70% of patients treated without internal fixation.44,53,133,159
Minor degrees of displacement may increase the risk of angular
deformity or growth disturbance. Gentle reduction has been recommended
by some authors.133,159
General anesthesia often is helpful to decrease associated muscle spasm
and diminish the risk of further injury to the physis, but Thomson et
al.159 observed that while reduction
under general anesthesia was more likely to be associated with anatomic
alignment it did not reduce the risk of premature physeal arrest. One
cause of failure of reduction is interposed periosteum which may become
entrapped in the fracture (see Fig. 23-4B). Although the alignment may be acceptable, the interposed periosteum, increases the risk of premature growth arrest.126
The technique of closed reduction depends on the direction and degree of displacement of the epiphysis (Fig. 23-13A,B).
Joint aspiration may precede manipulation. The periosteum is usually
intact in the direction of displacement of the distal fragment, which
is on the side of the metaphyseal fragment in a Salter-Harris type II
fracture. The first principle for reduction is to avoid harm to the
physis. The maneuver should be 90% traction and 10% leverage. The first
maneuver increases the deformity slightly while traction is applied.
The proximal edge of the displaced epiphysis can then be aligned with
the edge of the metaphysis on the same side as the periosteal tether.
Reduction is then completed by correcting angular deformity and


the fracture gap without sliding the distal fragment over the corner of
the femoral metaphysis. The sequence of events is to pull, tip, and
close the separation. Multiple attempts at closed manipulation are not
warranted and may increase the risk of growth disturbance.

FIGURE 23-13 Closed reduction and stabilization of a Salter-Harris type I or II fracture. A.
With medial or lateral displacement, traction is applied longitudinally
along the axis of the deformity to bring the fragments back to length. B.
For anterior displacement, the reduction can be done with the patient
prone or supine. Length is gained first, then a flexion moment is added.
Medial or Lateral Displacement. With patient supine, the
leg is grasped with the knee in extension and the hip in slight
flexion. The thigh is held by an assistant as moderate longitudinal
traction is exerted by a handhold on the leg above the ankle. If the
displacement of the epiphysis is medial, varus is increased gently and
cautiously to avoid stretching the peroneal nerve. With one hand
holding traction on the leg, the palm of the other hand is placed
against the concave surface of the angulated distal femur. The
epiphysis is pushed toward the metaphysis as the leg is realigned with
the thigh. Once reduction is obtained, longitudinal traction is
Anterior Displacement. Anterior displacement of the
epiphysis can be reduced with the patient either supine or prone. With
the patient supine, the hip is flexed approximately 60 degrees and the
thigh is held by an assistant. Longitudinal traction is applied with
the knee in partial flexion. Posterior pressure on the epiphysis is
exerted manually. With continuing traction on the leg, the knee is
flexed 45 to 90 degrees. Prone reduction requires fewer assistants. If
the reduction is done with the patient prone, traction is applied to
the limb, an assistant pushes down on the posterior aspect of the
proximal femur, and the knee is flexed approximately 110 degrees. This
sequence is similar to that for reduction of a supracondylar humeral
fracture. After reduction of an anteriorly displaced epiphysis, it is
important to check the pulses in the foot and ankle. Maintaining
reduction in a cast may be problematic following reduction of this type
of fracture. Immobilization of a swollen knee in flexion of more than
90 degrees may compromise the popliteal vessels and interfere with
circulation to the leg, and regaining extension of the knee may be
difficult after prolonged immobilization in flexion.55
In addition, judgment of frontal plane alignment is difficult in the
flexed knee. For this reason, casting in mild knee flexion of 20 to 30
degrees may be preferable.
Posterior Displacement. For reduction of posterior
displacement of the distal femoral epiphysis, the patient is placed
supine and the surgeon grasps the leg and exerts downward longitudinal
traction while the knee is held partly flexed. Longitudinal traction is
continued as the leg is brought up to extend the knee. An assistant
pulls up directly under the distal femoral epiphysis with one hand and
pushes down on the distal metaphysis of the femur with the other. Such
flexion type injuries can be immobilized in extension.36
Postreduction Management. X-ray and clinical follow-up
is recommended 5 to 7 days after immobilization to detect any
subsequent displacement. Union is normally rapid because the distal
femoral physis is a metabolically active area of bone formation.
Partial weight-bearing on crutches with touchdown gait can be started 2
to 3 weeks after injury. Cast immobilization is continued for
approximately 4 weeks in most cases, and this can be followed by a
removable knee immobilizer and gentle range-of-motion exercises. Full
weight-bearing is generally permitted 6 weeks after initial injury.
X-ray and clinical follow-ups at 6 and 12 months after injury are
recommended to detect early growth disturbances. Even nondisplaced
fractures should be followed until normal resumption of growth can be
Closed Reduction and Percutaneous Fixation
Salter-Harris Types I and II Fractures. Most displaced
Salter-Harris types I and II epiphyseal fractures of the distal femur
can be reduced by closed manipulation and stabilized with percutaneous
pins or screws under fluoroscopic control. Internal fixation maintains
anatomic reduction better than cast immobilization


and is recommended by most of the more recent authors on this subject.3,44,53,133,157,159,179
A basic principle is that fixation devices should avoid crossing the
physis if adequate fixation can be achieved without doing so.3
In Salter-Harris type I fractures as well as type II fractures with
small metaphyseal fragments, crossing the physis is necessary but
fracture stabilization is important to avoid loss of reduction during
the postoperative period. When traversing the physis is unavoidable,
smooth pins are recommended. Although it may not be possible to tell
with complete certainty whether a subsequent growth disturbance arose
from the injury or pins crossing the physis, clinical experience
suggests smooth pins crossing a physis are unlikely to cause a growth
disturbance. Studies in the rabbit model have determined that drill
holes of 2 to 2.5 mm (3% to 5% of physeal area) do not cause growth
Thus, it is unlikely that a 3 to 3.5 mm (one eighth of an inch) smooth
pin would contribute to growth disturbance following fixation of a
distal femoral epiphyseal fracture. Pins should be widely separated at
the fracture site (see Fig. 23-7C), which is
generally easiest to achieve by inserting the pins at a high angle so
they cross proximal to the physis. Pins can be inserted from each
condyle across the fracture and into the femoral metaphysis, or both
pins can be inserted laterally with one entering the lateral femoral
shaft and proceeding distally and medially. The other pin then enters
the distal femoral epiphysis and proceeds proximally and medially to
engage the opposite cortex. The pins can be cut off under the skin
before application of a long-leg cast or left percutaneous. Infection
is frequent if pins in this region are left out through the skin for
longer than 4 weeks, and intra-articular pins may lead to a septic
knee. If the metaphyseal fragment is large enough, cannulated screws
can be directed transversely across the metaphysis after reduction (Fig. 23-14; see also Fig. 23-8C).
Stability should be gently tested because the metaphyseal spike may not
be firmly attached to the epiphysis in high-energy injuries with
comminution. After stabilization with pins or screws, the lower
extremity is immobilized in a long-leg cast. Postoperative management
is similar to that after closed reduction without fixation. Pins are
generally removed 2 to 3 weeks after fracture, with continued cast
immobilization for a total of 4 weeks.

FIGURE 23-14 Screw fixation following closed oropen reduction of Salter-Harris type II fracture with a large metaphyseal fragment. A.
When using cannulated screws, place both guidewires before screw
placement to avoid rotation of the fragment while drilling or inserting
screw. Screw threads should be past the fracture site to enable
compression. Washers help increase compression. Screws may be placed
anterior and posterir to each other, which is particularly helpful when
trying to fit multiple screws in a small metaphyseal fragment. B. This form of fixation is locally “rigid,” but must be protected with long-leg immobilization or long lever arm.
Salter-Harris types III and IV separations generally
require open reduction to obtain anatomic alignment, although
arthroscopic-assisted reduction and percutaneous fixation of a
Salter-Harris type IV fracture have been described.83
Open Reduction of Physeal Fractures
Salter-Harris Types I and II Fractures. Open reduction
is indicated for irreducible Salter-Harris types I and II fractures and
for most displaced Salter-Harris types III and IV fractures. Open
reduction is also appropriate for open fractures or when associated
injuries mandate it (i.e., vascular or ligament injury). A tourniquet
around the proximal thigh can be used for temporary hemostasis if it is
placed proximally enough to avoid binding the thigh muscles under the
inflated tourniquet. How much of a “fracture gap” of a type II fracture
is acceptable is open to debate. Interposed periosteum may contribute
to growth arrest125,126 and has been identified as a possible cause of growth arrest in distal tibial physeal fractures.8 Anatomic reduction is recommended, with less than 2-mm gap following reduction.44,71
Surgical approach is determined by the direction of
fracture displacement because the apex of deformity is the most likely
location of any obstacles to reduction. For a Salter-Harris type II
separation in the coronal plane, a longitudinal incision over the
distal femoral metaphyseal fragment gives direct exposure of any
obstacles to reduction and avoids disruption of the periosteal hinge.
If the displacement is anterior, exposure is best obtained with a
standard medial approach at the anterior border of the sartorius
because this can be extended to expose the popliteal artery if
necessary. After exposure of the fracture, irrigation and removal of
clotted blood permit better inspection of the separation. Interposed
muscle or a flap of periosteum may be identified and removed between
the epiphysis and metaphysis. Special care is taken to avoid any
additional damage to the physis. Once the muscle and periosteal flap
are removed, reduction is carried out primarily with traction and
gentle realignment. To avoid damage to the physis, instruments should
not be placed in the physeal interval. Fixation should be performed as
described previously. After closure of the wound, a long-leg or hip
spica cast is applied.
Salter-Harris Types III and IV Fractures. Open reduction
with internal fixation is almost always necessary for displaced
Salter-Harris types III and IV fractures of the distal femur. Precise
reduction and rigid internal fixation restored articular congruity and
can reduce the risk of growth arrest.51 An anteromedial or anterolateral longitudinal incision is used (Fig. 23-15).
For severely comminuted fractures, an anterior approach may be chosen
with a future total knee replacement in mind. The anterior physeal and
articular margins of the fracture are exposed. Reduction is checked by
noting the apposition of the articular surfaces, the physeal line
anteriorly, and the fracture configuration (see Fig. 23-15). Final reduction can be confirmed with fluoroscopy. The gastrocnemius has been reported as an obstacle


to reduction in a Salter-Harris type III fracture of the medial femoral epiphysis.1
Provisional stabilization is obtained with Kirschner wires (K-wires).
When reduction is accomplished, screws are directed transversely across
the epiphysis in Salter-Harris type III separations or across the
metaphysis and epiphysis in Salter-Harris type IV injuries (see Figs. 23-10, 23-14, and 23-15)
If crossing the physis with fixation is unavoidable, smooth pins should
be used. A coronal plane fracture, or Hoffa fracture, usually involves
the lateral condyle and is approached through an anterolateral incision
except for the unusual medial condyle coronal plane fracture, which the
approach is anteromedial.110
Fixation is generally a lag screw inserted from anterior to posterior.
It may be possible to use an extra-articular starting point.138
Otherwise, the screw can be placed perpendicularly through the
articular surface with the screw head or headless screw slightly buried
beneath the articular surface. Alternatively, Jarit et al.74
demonstrated in cadavers that posterior to anterior stabilization is
more stable, but a small posterolateral exposure is required for screw
insertion. After reduction and fixation, the knee joint is thoroughly
irrigated and inspected for other fractures and ligament disruption.
The limb is immobilized in a long-leg cast in addition to the internal
fixation. Postoperative management is as described on page 873.

FIGURE 23-15 Open reduction of displaced lateral Salter-Harris type IV fracture of the distal femur. A.
A longitudinal skin incision, cheating anteriorly if fracture severity
raises concern of needing total knee replacement in future. B.
Alignment of joint and physis are used to judge reduction. Guidewires
for cannulated screws placed above and below physis, parallel to
physis. C. Screws inserted in compression
with washer on metaphyseal fragment. Washer is optional in epiphyseal
fragment if later prominence is of more concern than need for
additional compression.
The use of indomethacin to reduce the incidence of
growth disturbance in a rabbit distal femoral fracture model has been
reported with equivocal results.149
Although nonsteroidal anti-inflammatory medications have been shown to
inhibit callus formation, recommendations for this treatment to prevent
growth arrest are premature.
Surgery for Associated Injuries
If an associated collateral ligament injury is
identified with preoperative imaging or at the time of surgery, it can
be repaired at the time of open reduction. Otherwise, internal fixation
is used to allow early mobilization and rehabilitation of both the
physeal separation and the ligamentous injury. As noted previously, a
rehabilitation program is initiated following union of the fracture
when there is a cruciate ligament tear without meniscal injury. If
there is a repairable meniscal tear and a cruciate ligament tear, then
cruciate ligament reconstruction can be done at the time of meniscal
repair depending on the patient’s age and activity level (see Chapter 24).
If vascular repair is indicated, a posterior modified
S-shaped incision or medial approach is used to follow the course of
the femoral artery. The medial incision is usually preferred because it
provides adequate exposure of the fracture and the artery. Care should
be taken during the incision because the vessel may be superficial
beneath the skin, particularly in an anteriorly displaced fracture. The
hamstring tendons may be “bowstrung” around the femoral metaphysis. The
artery may be in spasm, occluded by intimal tear, or disrupted. After
the vascular structures are identified, the fracture is reduced and
stabilized rapidly before vascular repair, except as noted earlier on
page 847.
External Fixation
When access is needed for treatment of severe
soft-tissue injuries or staged surgeries are planned, external fixation
may be indicated. Spanning external fixation may also be indicated in
combination with limited internal fixation for severely comminuted
fractures or other special circumstances. Because of the risks of
secondary knee joint infection and loss of motion, external fixation is
not indicated for most distal femoral physeal fractures.161
Rigid Plate Fixation
Rigid compression plate fixation across the physis will
stop all remaining growth while the plate is in place. Standard screw
fixation of the plate to bone may crush the perichondral ring and
contribute to growth arrest; however, more modern periarticular locking
compression plates may allow fixation with the plate slightly elevated
from the physis and bone. Also, unicortical fixation is sufficient in
some fracture segments. These plates may eventually provide a method of
temporary fixation of some epiphyseal fractures to reduce damage to the
physis. After bone union, the plates need to be removed so that growth
can resume in a manner similar to temporary staples for guided growth.
At the time of this writing, this option is reserved for adolescents


near the end of growth and children with severe injuries in which severe growth disturbance is believed to be inevitable.

Pearls and Pitfalls
  • When the knee is swollen in infants and
    children, distal femoral epiphyseal separation associated with
    difficult deliveries, child abuse, myelodysplasia, or other pathologic
    conditions should be suspected.
  • Minimally displaced fractures of the distal femoral epiphysis are at risk for further displacement.
  • A significantly painful knee examination
    with normal x-rays warrants stress x-rays or MRI to detect obscure
    distal femoral or proximal tibial epiphyseal fractures.
    • Stable fixation with pins or cannulated screws is recommended for all fractures that require reduction.
    • When a cast is used, it should be
      extended as far proximally as possible and molded at the proximal thigh
      into a triangular shape to provide a small amount of rotational support.
    • Repeat x-rays are obtained 5 to 7 days after injury and treatment.
  • Growth disturbance is frequent and troublesome, especially between the ages of 2 and 12 years.
    • Reduction is 90% traction and 10% leverage.
    • Multiple closed reduction attempts should be avoided.
    • Follow-up with full-length x-rays of both legs at 3, 6, and 12 months after injury is essential.
  • Associated ligamentous injuries may be present.
    • Joint stability should be checked following union.
    • MRI should be considered, especially for type III injuries.
  • P.860
  • Stiffness is not uncommon.
    • The cast is removed at 4 weeks and a knee immobilizer is applied for most cases.
    • Gentle range of motion is begun early, but forceful manipulation must be avoided because of the risk of added injury (Table 23-4).
TABLE 23-4 Distal Femoral Physeal Fractures: Pitfalls and Prevention


Preventative Strategy

Missed diagnosis

Immobilize and re-examine if uncertain, or MRI

Be cognizant of nondisplaced injury in infants, pathologic conditions, multitrauma, or unresponsive patients

Redisplacement of fracture

Pin or screw fixation for all fractures that require reduction

Radiographs at 5-7 days postinjury

High long-leg cast with triangular molding proximally or spica cast

Growth disturbance

Minimize trauma at reduction

Follow-up at 6, 12, and possibly 24 months with full-length radiographs of both lower extremities

Knee joint instability

Check ligaments when fracture stabilized or healed

Consider MRI, especially for type III fractures


Avoid prolonged immobilization

Remove casts in 4 weeks and apply knee immobilizer with gentle range of motion in most cases

Avoid manipulation due to risk of added injury

Complications of fractures of the distal femoral epiphysis are listed in Table 23-5.
Recurrent Displacement and Late Reduction
Redisplacement has been reported in 30% to 70% of
patients immobilized in a long-leg cast following reduction of
displaced fractures without internal fixation.44,53,133,159 Eid et al.44
reported that a hip spica cast reduced the risk of redisplacement, but
loss of reduction still occurred in 10% of their patients treated in a
spica cast. Late reductions may be problematic whether performed for
redisplacement or for initial treatment. Rang and Wenger131
advised that multiple attempts at closed reduction, or reductions more
than 7 to 10 days after fracture, may do more damage to the physis. An
experimental study in rats did not demonstrated increased risk of
growth disturbance associated with physeal fractures reduced at the
human equivalent of 7 days after injury; however, attempts at reduction
at the equivalent of 10 days resulted in diaphyseal fracture rather
than reduction of the epiphysis.42 Based on this study and opinions of others, it seems reasonable to attempt closed reduction


before fixation up to 10 days following initial distal femoral epiphyseal separation.64,131
After 10 days, open reduction may be required to re-establish
alignment. When fractures are treated more than 10 days after initial
injury, it may be better to observe Salter-Harris types I and II
fractures for possible remodeling or to perform later osteotomies
rather than perform open reduction. For displaced Salter-Harris types
III and IV fractures that are treated late, open reduction is
recommended as soon as possible to restore articular congruity.102

TABLE 23-5 Complications of Fractures of the Distal Femoral Epiphysis

Number of Patients

Ligamentous Injury

Neurovascular Problems

Angular Deformity






















14% clinical


68% radiographic















Two anterior cruciate ligrament injuries






8% symptomatic





14% asymptomatic













* Series contains referred patients and may not represent true incidence.

Salter-Harris type II fractures only.

Physeal Injury
The most common complication of distal femoral
epiphyseal fracture is growth disturbance with angular deformity or
shortening. This has been reported in 35% to 50% of patients regardless
of anatomic reduction.3,44,53,71,89,154,159
Salter-Harris types I and II fractures in other areas of the body
usually have a low risk of growth arrest, but even minimally displaced
fractures in the distal femur should be followed closely for growth
arrest (see Fig. 23-16) Growth disturbance is uncommon in patients younger than 2 years of age due to the flat shape of the physis in this age group.133
In juveniles, more energy is required to disrupt the physis and the
complex shape of the physis may predispose to fracture lines that
extend through multiple regions of the physis regardless of fracture
type.133 In adolescents, less force
is required to disrupt the physis, but the consequences of growth
arrest are not as severe as in patients between the ages of 2 and 12
When growth arrest occurs, it usually is evident by 6
months after distal femoral epiphyseal fracture. The distal femur grows
approximately 1 cm a year and growth should resume within this time
frame. Full-length standing x-rays of both lower extremities are
recommended as soon as possible following the initial injury. These are
repeated approximately 6 months later to identify early angular
deformity or increasing length discrepancy. Bilateral AP and lateral
femoral x-ryas 6 months after injury should demonstrate growth arrest
lines (Park-Harris lines) that can be examined for symmetry and
alignment. Growth arrest lines develop when there is a temporary
slowing of growth during periods of malnutrition, trauma, chemotherapy,
or alcohol consumption.52,61,112,120
The normal longitudinal orientation of the zone of provisional
calcification becomes dense and interconnected, forming a transverse
line in the metaphysis. After growth resumes, this dense layer moves
away from the physis and is visible on x-rays as a radiodense line of
bone in the metaphysis.112 If the
line is growing symmetrically away from the physis, then normal growth
has resumed. Failure of a Park-Harris line to appear is evidence of
premature growth arrest when a line is visible in the uninjured distal
femoral metaphysis. An oblique Park-Harris line that converges toward
the physis indicates asymmetrical growth caused by a bone bridge across
the physis that is preventing growth of one side of the physis. When
there is doubt about premature physeal closure, screw removal is
recommended before an MRI study. Growth disturbance can be detected by
MRI as early as 2 months after injury.41
Fat-suppressed three-dimensional spoiled gradient-recalled echo
sequence MRI technique has been described as the best method for
diagnosis and follow-up of premature physeal arrest.41
Physeal Arrest with Progressive Angulation
Early recognition and management of progressive
angulation can reduce the need for osteotomy if diagnosis is made
before a clinically significant deformity develops. After deformity has
developed, an osteotomy is generally required whether bar excision is
performed or not. The risk of significant angular disturbance is
greatest in patients with significant growth remaining. When asymmetric
growth follows a type II separation, the portion of the physis
protected by the Thurston-Holland fragment is usually spared. The
localized area of growth inhibition occurs in that portion of the
physis not protected by the metaphyseal fragment. Therefore, if the
metaphyseal spike is medial, deformity is more likely to be valgus due
to lateral growth arrest.
If a localized area of premature arrest constitutes less
than 50% of the total area of the physis and at least 2 years of growth
remains, excision of the bony bridge has been recommended.80,123 Although Langenskiöld82 reported normal resumption of growth in 80% of patients, others have reported normal growth in only 25% to 50% of patients.16,23,62,174
Therefore, bilateral epiphysiodesis should be considered when there is
less than 3 to 4 cm of growth remaining and deformity is minor.
Hemiepiphysiodesis alone is not an option for correcting deformity when
a bone bridge already exists on one side of the physis. However,
ipsilateral hemiepiphysiodesis combined with contralateral total
epiphysiodesis can maintain the current status of length and alignment
when growth arrests are diagnosed early in adolescent patients. We
recommend bar excision without osteotomy in an attempt to restore
growth when angular deformity is 5 to 20 degrees, there are more than 2
years of growth remaining, and the area of bar is less than 33% of the
area of the physis. Osteotomy at the time of physeal resection is
recommended when angular deformity exceeds 20 degrees.80,123
For bone bridges larger than 33% of the area of the physis or when
angulation is more than 20 degrees, we recommend osteotomy with
bilateral epiphysiodesis or ipsilateral lengthening depending on the
extent of growth remaining and current amount of discrepancy.
Descriptions of techniques for bar excision, epiphysiodesis, osteotomy,
or lengthening are beyond the scope of this text and are well-described
in other textbooks or periodicals.
Physeal Injury with Leg-Length Discrepancy
Limb-length discrepancy is a frequently reported complication of distal femoral physeal fractures,3,44,71,133,159 but the amount of discrepancy may not be clinically relevant.3,71 Up to 2 cm of limb-length inequality does not cause significant gait disturbance or clinical symptoms in adulthood.50,57,150 The distal femoral epiphysis grows at a rate of approximately 1 cm per year until skeletal maturity.2,172
Thus, when the patient is within 2 years of skeletal maturity at the
time of injury, the shortening probably will be insignificant. Serial
scanograms for calculation and timing of epiphysiodesis are not helpful
following posttraumatic distal femoral growth arrest. When complete
distal femoral arrest is diagnosed, the only method to prevent
progressive discrepancy is immediate epiphysiodesis of the
contralateral distal femur. Thus, the only decision following diagnosis
is whether to close the opposite physis, allow the discrepancy to
increase within physiological limits, or plan for limb lengthening.
Limitation of knee motion after separation of the distal
femoral epiphysis may be caused by intra-articular adhesions, capsular
contracture, or muscular contracture. This should be treated with
active and active-assistive range-of-motion exercises. Following


immobilization and osteoporosis, periarticular fractures from
overzealous manipulation for knee contracture has been reported.30
Drop-out casts and dynamic braces may be of benefit for persistent
stiffness. For patients with stiff knees in whom conservative treatment
has failed, surgical release of contractures and adhesions, followed by
continuous passive motion, may regain significant motion.146

Stress X-rays
presented a cogent argument against the use of stress views to
differentiate between a collateral ligament injury and a physeal
fracture of the distal femur. He reported that this test may have been
needed in the past, when the treatment of a collateral ligament injury
was operative and the treatment of a nondisplaced physeal fracture was
immobilization. Stanitski152 argued
that, because the current initial treatment of both a collateral
ligament injury and a nondisplaced femoral fracture is immobilization,
the need for an immediate diagnosis and stress views is no longer valid.
Special Imaging Studies
When to obtain an MRI or CT scan is also controversial.
There is no clear answer at the current time. Some prefer an MRI for
diagnosis of obscure injuries because of comfort to the patient along
with the potential to diagnose associated ligamentous or chondral
injuries and bone contusions.98,151
An MRI should always be considered for evaluation of type III fractures
of the medial condyle because the mechanism of injury is similar to the
“triad” injury associated with anterior cruciate ligament and meniscal
disruption.98 Also, MRI is preferred for evaluation of partial or complete growth arrest.41
A CT scan is preferred to assess fracture patterns for surgical
fixation, especially when there is metaphyseal comminution and
intra-articular involvement.
Proximal tibial physeal injuries account for less than 1% of all physeal separations.96,124 In contrast to the distal femoral physis, the proximal tibial physis has intrinsic anatomic stability.25
For this reason, separation of the proximal tibial epiphysis requires
significant force. The collateral ligaments provide some protection
from epiphyseal disruption. On the lateral side, the fibula also
provides a buttress for the proximal tibial epiphysis. Anteriorly, the
tibial tubercle projects distally from the epiphysis and overhangs the
adjacent metaphysis. This provides some stability for anterior and
posterior translational forces. Avulsion injuries of the tibial
tuberosity are discussed in the next section. These are very rare prior
to adolescence. Perhaps the most critical feature of fractures of the
proximal tibial epiphysis is the proximity and tethering of the
popliteal artery to the posterior tibia. This increases the risk for
associated vascular injury. Treatment consists of careful observation
and management of associated injuries along with anatomic reduction and
stable fixation of displaced fractures.
Mechanism of Injury
These injuries are usually due to motor vehicle trauma,
sports activities, or other traumatic events such as lawn mower
accidents. Child abuse has been reported to cause a Salter-Harris type
II fracture.158 Separations of this epiphysis can also occur during passive manipulation of the lower limbs in infants with arthrogryposis.39
Hyperextension force is a common mechanism, with the metaphyseal
fragment displacing posteriorly. Valgus stress can open the physis
medially with the fibula acting as a lateral resistance force.176
Rarely, a flexion force can cause a Salter-Harris type II or III
fracture. This flexion fracture pattern has a mechanism similar to that
of tibial tuberosity avulsion injuries.
Signs and Symptoms
Physical Examination
A patient with a separation of the proximal tibial
epiphysis usually presents with pain, knee swelling, and a
hemarthrosis. Limb deformity may or may not be present. Extension is
limited because of hamstring spasm. Pain is present over the proximal
tibial physis distal to the joint line. When the proximal metaphysis of
the tibia is displaced posteriorly, a concavity is seen clinically and
can be palpated anteriorly at the level of the tibial tubercle. If the
metaphysis is displaced medially, a valgus deformity is present. There
may be tenderness or angulation of the proximal fibula as well. When
the proximal end of the metaphysis protrudes under the subcutaneous
tissues on the medial aspect of the knee, a tear of the distal end of
the MCL should be suspected. Vascular status should be carefully
evaluated, including distal pulses and warmth and color of extremity
should be noted. Compartments should be assessed by palpation and by
assessment of sensation plus passive and active ankle and toe motion,
especially active dorsiflexion.
X-ray Findings
Nondisplaced separations may not be visible on x-ray. An
associated hemarthrosis may be identified as an increased distance
between the patella and distal femur on a lateral view. Small fracture
lines may be seen extending proximally through the epiphysis or
distally through the metaphysis. A tiny bony fragment at the periphery
of the metaphysis may be the only clue to the diagnosis. Other fracture
lines may be visible only on oblique views. Differentiating a proximal
tibial physeal fracture from a ligament injury should be attempted at
time of presentation, and stress views may be warranted. However, the
same concerns regarding stress films are present with proximal tibial
epiphyseal fractures as with distal femoral epiphyseal fractures. MRI
is a safe, accurate, and more comfortable method for diagnosis of
obscure fractures or ligamentous injuries.151
CT scans may be helpful to determine treatment for Salter-Harris types
III and IV injuries because it provides better identification of the
fracture pattern, articular incongruity, and metaphyseal comminution.
Associated Injuries
Ligamentous Injuries
Internal derangement of the knee joint may occur with
separation of the proximal tibial epiphysis and may be unrecognized.
One series reported concomitant avulsion of the tibial eminence in 40%
of patients with types III and IV fractures.128

Vascular Injuries
The most serious injury associated with proximal tibial physeal fracture is vascular compromise.25,144,177
The popliteal artery is tethered by its major branches near the
posterior surface of the proximal tibial epiphysis. The posterior
tibial branch passes under the arching fibers of the soleus. The
anterior tibial artery travels anteriorly over an aperture above the
proximal border of the interosseous membrane. A hyperextension injury
that results in posterior displacement of the proximal tibial
metaphysis may stretch and tear the tethered popliteal artery (Figs. 23-17 and 23-18).
Routine angiography is not mandatory because ischemia
usually resolves following reduction, but motor function, pulses,
warmth, and color should be checked frequently during the initial 48 to
72 hours. It is important to remember that even a fracture that appears
minimally displaced at presentation in an emergency department may have
had significant displacement at the time of injury, particularly in
motor vehicle accidents (see Fig. 23-18).160
Careful attention to evaluating and monitoring the arterial status is
particularly warranted for proximal tibial physeal fractures. Arterial
insufficiency may result from either a tear in the popliteal artery at
the time of epiphyseal separation or from a compartment syndrome. Delay
in recognition results in delay of treatment, which is potentially
catastrophic. Arteriography for isolated injuries but may be helpful
when vascularity is questionable. Fracture fixation is generally
recommended before vascular repair, as discussed for distal femoral
epiphyseal fractures. The extended medial approach usually provides the
best approach for fracture and vessel management, but the posterior
approach provides easier access to the popliteal space and can be used
with percutaneous fixation of the fracture. The lateral approach is
rarely used for vascular access except for localized injuries to the
bifurcation of the popliteal artery.
FIGURE 23-17
Posterior displacement of the epiphysis following fracture-separation
at the time of injury can cause arterial injury. In addition, a
posteriorly displaced fragment can cause persistent arterial occlusion
by direct pressure. (Reprinted with permission from Skaggs DL, Flynn
JF. Trauma about the knee, tibia, and foot. In Skaggs DL, Flynn JF,
eds. Staying out of Trouble in Pediatric Orthopaedics. Philadelphia:
Lippincott Williams & Wilkins; 2006.)
Nerve Injuries. Peroneal neuropathy associated with a
separation of the proximal tibial epiphysis usually recovers
spontaneously with time. Therefore, observation is recommended unless
there is an open wound with possible sharp trauma to the nerve.
Diagnosis and Classification
Proximal tibial epiphyseal separations are usually
described by Salter-Harris type along with direction and amount of
displacement (Table 23-6). A specific
classification for these fractures has not been proposed. Most
separations of the proximal tibial epiphysis are Salter-Harris types I
and II injuries. The frequency of Salter-Harris type III injuries may
be skewed by the inclusion of displaced avulsion fractures of the
tibial tubercle. The incidence of Salter-Harris type IV injuries
depends on whether certain open injuries to the knee are included
(i.e., lawnmower injuries).25 Fifty
percent of Salter-Harris type I separations of the proximal tibia are
nondisplaced. When these fractures are displaced, the metaphysis is
usually medial or posterior relative to the epiphysis.
Presumably, the overhanging tubercle prevents anterior
displacement and the fibula prevents lateral displacement of the
metaphysis. There may be an associated fracture of the proximal
diaphysis of the fibula or a separation of the proximal fibular
epiphysis. Two thirds of Salter-Harris type II fracture-separations of
the proximal tibial are displaced. Displacement of the tibial
metaphysis usually is medial (Fig. 23-19), and
the associated metaphyseal fracture usually is lateral, resulting in
valgus deformity. The proximal fibula may also be fractured.
Salter-Harris type III separations have a vertical fracture line
through the proximal epiphysis into the articular surface to the
physis. There is some controversy about whether intra-articular tibial
tubercle avulsion fractures should be included as a type III proximal
tibial physeal fracture.144
Generally, this fracture is not included in series of tibial epiphyseal
fractures. When the fracture line of a tibial tubercle avulsion
fracture is visible on the AP view, we consider it a proximal tibial
epiphyseal fracture. If, on the other hand, the fracture line is
visible only on the lateral film, then we consider it as a tibial
tubercle fracture (see Fig. 23-26). When
avulsion fractures of the tibial tubercle are excluded from
Salter-Harris type III injuries, the most common fracture involves the
lateral epiphysis, and this is frequently accompanied by a tear of the
ligament. This lateral fragment usually requires internal fixation, and
the ligament may need surgical repair. Triplane and coronal split
fractures of the proximal tibial epiphysis have also been described.
These occur through a partially closed physis during the normal
sequence of physeal closure.34,63,122
Salter-Harris type IV injuries can involve the medial or
lateral tibial plateau. Salter-Harris type V injuries are rare but have
been reported in the proximal tibia.79
Usually, the diagnosis of a type V injury is made in retrospect when
progressive angulation or leg-length discrepancy is noted. Another type
of proximal


tibial epiphyseal fracture is of an avulsion of lateral tibial condyle. Sferopoulos et al.143
described seven patients with either a fracture of Gerdy’s tubercle or
a Segond fracture. All were sustained during a sporting event, and all
were treated nonoperatively in a cylinder cast for 6 weeks. All of the
patients returned to sports between 3 and 4 months after injury. Of
note, two patients also had a concomitant and ipsilateral fractures of
the anterior intercondylar eminence.

FIGURE 23-18 Child on back of bicycle struck by car sustained ipsilateral proximal femoral and tibial shaft fracture. A,B. Proximal tibial physeal fracture on initial radiographs were not appreciated. C.
Following external fixation of the tibial diaphyseal fracture, a
Salter-Harris type I fracture of the proximal tibial physeal is
evident. D. Closed reduction and K-wire fixation were used to treat the proximal tibial physeal fracture. E.
Compartment syndrome occurred, which is associated with proximal
physeal fractures of the tibia. In this case, the contribution of
concomitant injuries to the compartment syndrome is difficult to
discern. (A and E
reprinted with permission from Skaggs DL, Flynn JF. Trauma about the
knee, tibia, and foot. In Skaggs DL, Flynn JF, eds. Staying out of
Trouble in Pediatric Orthopaedics. Philadelphia: Lippincott Williams
& Wilkins; 2006.)

TABLE 23-6 Classifications and Implications of Proximal Tibial Physeal Fractures



Mechanism of injury

I. Hyperextension

Risk of vascular disturbance

II. Varus/valgus

Usually results from jumping; very near maturity

III. Flexion

See tibial tubercle fractures, type IV, in the next section

Salter-Harris pattern


Fifty percent nondisplaced


Thirty percent nondisplaced


Associated collateral ligament injury possible




Has been reported; diagnosis usually late

Proximal tibial epiphyseal fractures also can be classified by the direction of deformity (Fig. 23-20). This classification may help recognize potential complications and plan the reduction


technique. The classic hyperextension type has an apexposterior
angulation and results from forced hyperextension. Varus and valgus
types result from abduction or adduction forces. A flexion type injury
may separate the entire proximal tibial epiphysis in a manner similar
to avulsion of the tibial tubercle except that the epiphysis stays
intact as it separates from the metaphysis.72,137

FIGURE 23-19 A.
Salter-Harris type II separation of the proximal tibial metaphysis,
with medial displacement of the proximal tibial metaphysis and complete
fracture of the upper third of the fibula. B. After reduction and percutaneous fixation with a 4.5-mm cannulated screw.
FIGURE 23-20 Classification of proximal tibial physeal fractures by direction of displacement. A. Type I: hyperextension type usually caused by direct force. Risk of vascular damage exists. B.
Type II: varus or valgus type. Vascular injury is uncommon. Reduction
may be inhibited by interposition of pes anserinus or periosteum.
Surgical and Applied Anatomy
Bony Anatomy
The ossific nucleus of the proximal tibial epiphysis is
normally present at birth. It lies in the center of the cartilaginous
anlage, somewhat closer to the metaphysis than to the articular
surface. Occasionally, the ossification center is double. The secondary
center in the tubercle appears between the ages of 9 and 14 years. The
proximal epiphyseal ossification center unites with the tubercle and is
almost completely ossified by age 15.
The lateral edge of the physis is separated from the
proximal tibiofibular joint by a thin layer of joint capsule.
Hemorrhage from an epiphyseal separation may extend into the adjacent
tibiofibular joint cavity and through it into the knee joint itself.
The physis closes from central to anteromedially followed by
posteromedial closure.72,116
Soft Tissue Anatomy
The collateral ligaments provide some protection from
epiphyseal disruption. The superficial portion of the MCL extends
distal to the physis inserting into the medial metaphysis of the tibia.
The lateral collateral ligament inserts on the proximal pole of the
fibula. The patellar ligament attaches to the secondary ossification
center of the tibial tuberosity that forms the anterior extension of
the physis. This attachment can lead to avulsion injuries of the
anterior epiphysis, but these are uncommon until adolescence when the
quadriceps becomes stronger and the physis weaker. Also, some fibers
extend distal to the physis into the anterior aspect of the upper
tibial diaphysis. The synovium and the capsule of the knee joint insert
into the proximal tibial epiphysis proximal to the physis. There is a
defect in the capsule where the popliteus tendon runs over the
posterolateral corner of the tibia. The capsular ligament anchors the
menisci to the tibial epiphysis medially and laterally.
Vascular Anatomy
The distal portion of the popliteal artery lies close to
the posterior aspect of the proximal tibia. Firm connective tissue
septa hold the vessel against the knee capsule. The popliteus muscle
intervenes between the artery and bone (Fig. 23-21).
The lateral inferior geniculate artery runs across the surface of the
popliteus muscle, anterior to the lateral head of the gastrocnemius,
and turns forward underneath the lateral collateral ligament. The
medial inferior geniculate artery passes along the proximal border of
the popliteus muscle, anterior to the medial head of the gastrocnemius,
and extends anterior along the medial aspect of the proximal tibia. The
popliteal artery divides into the anterior tibial and posterior tibial
branches beneath the arch of the soleus muscle.
The proximal tibial epiphysis derives much of its blood
supply from an anastomosis between the geniculate arteries. The lateral
tibial condyle derives its blood supply anteriorly from the anterior
tibial recurrent artery and posteriorly from branches of the inferior
lateral geniculate artery.35,60 Hannouche et.al.60
suggested that the standard anterolateral approach to the lateral
tibial condyle with submeniscal arthrotomy may damage the epiphyseal
FIGURE 23-21
Posterior anatomy of the right popliteal region. Note that the
popliteal vessels are protected from bone (especially the tibia) only
by the popliteus muscle. The vessels are tethered by the geniculate
branches and by the trifurcation of the popliteal artery into the
peroneal, posterior tibial, and anterior tibial arteries. Note that the
anterior tibial artery passes anteriorly between the proximal tibia and
fibula, thus causing the popliteal artery to press against a
posteriorly displaced tibial metaphysis. ATA, anterior tibial artery;
LCL, lateral collateral ligament; LG, lateral gastrocnemius head; LIGA,
lateral inferior geniculate artery; MCL, medial collateral ligament;
MG, medial gastrocnemius head; MIGA, medial inferior geniculate artery;
SM, semimembranosus.
Current Treatment Options
Closed Reduction and Immobilization
Types I and II fractures usually can be treated with closed reduction (Table 23-7).
Traction is important during reduction to minimize the risk of damage
to the physis. Hyperextension fractures are reduced with traction in
combination with gentle flexion. A fracture with valgus angulation can
usually be reduced by adducting the leg into varus with the knee
extended. This should be done with gentle manipulation to decrease the
risk of injury to the peroneal nerve. After reduction, a long-leg cast
with varus molding is applied with the knee in slight flexion.
Closed Reduction and Fixation
Separations of the proximal tibial epiphysis may be
surprisingly unstable. Reducible but unstable types I and II fractures
can be stabilized with smooth pins inserted percutaneously.
Salter-Harris type II fractures with a large metaphyseal spike can be
stabilized with compression screws that fix the spike to the metaphysis
without crossing the physis (see Fig. 23-19).

TABLE 23-7 Methods of Treatment for Proximal Tibial Epiphyseal Fractures




Closed reduction and immobilization

Avoids anesthesia

High risk of loss of reduction. May require significant knee flexion for hyperextension injuries.

Nondisplaced, stable fractures

Closed reduction and smooth pin or screw fixation

Minimal dissection

Intra-articular pins may lead to joint infection or require later removal.

Reducible Salter-Harris type I and II fractures

Open reduction and screw or pin fixation

Anatomic reduction


Nonreducible Salter-Harris type I and II fractures, displaced Salter-Harris type III and IV fractures

Open Reduction
Salter-Harris II fractures that cannot be anatomically
reduced require open reduction for removal of soft tissue
interposition. The pes anserinus and periosteum have been reported as
obstructions to reduction of Salter-Harris type II fractures.31,158,176
Operative fixation of a Salter-Harris type I or II hyperextension
injury is recommended to facilitate wound management when vascular
repair is necessary. Pin or screw fixation in an expeditious manner is
generally recommended before vascular repair.
Open reduction is indicated for displaced Salter-Harris
types III and IV injuries. An anterior incision is used to allow
inspection of the articular surface. Anatomic reduction is performed,
using the joint surface as a guide. A pin can be inserted in the
displaced fragment as a joystick to assist reduction if needed. Smooth
pins or screws are then inserted horizontally across the epiphysis in
type III fractures. Metaphyseal and epiphyseal screws parallel to the
physis are recommended for Salter-Harris type IV fractures to avoid
physeal damage and allow growth to resume. A torn meniscus should be
repaired if possible.

Pearls and Pitfalls
  • X-rays should be scrutinized for nondisplaced proximal tibial fractures especially for
    • children with knee pain following trauma.
    • patients with polytrauma.58,143
  • Observation in the hospital is
    recommended for all fractures of the proximal tibia because of the risk
    of vascular injury or development of compartment syndrome.
  • All casts should be bivalved or nonconstricting splints should be used for early immobilization.
  • Unrecognized or late presentation of arterial injury.
    • Even minimally displaced fractures may have arterial injury from displacement at time of injury.
  • Compartment syndrome.
  • Nondisplaced fractures can be misdiagnosed as medial collateral ligament injuries.169 Stress x-rays or MRI can help make the correct diagnosis.
  • Proximal tibial growth disturbance can occur following diaphyseal fractures.66,107
    • This may be due to unrecognized trauma or generalized response to injury.
    • Recurvatum is the most common deformity
      and must be carefully assessed on lateral x-rays with comparison to the
      contralateral side. Osteotomy may be necessary for correction.119
  • Intra-articular pin placement can lead to a septic joint.
  • An unrecognized anterior cruciate ligament/tibial spine avulsion can cause late instability.
Complications reported in three series of proximal tibial epiphyseal injuries are summarized in Table 23-8.25,144,177
Loss of Reduction
Separations of the proximal tibial epiphysis can be
unstable, regardless of the Salter-Harris type. It is wise to obtain
x-rays 1 week after injury to verify alignment. At that point, it is
still possible to remanipulate if necessary. This complication can
usually be avoided by using screw or smooth pin fixation following
fracture reduction.
TABLE 23-8 Complications of Proximal Tibial Physeal Fractures*



Ligamentous Instability

Growth Disturbance




Not reported

















*Includes 10 cases of tibial tubercle avulsion with intra-articular extension as type III fractures.

See section on associated injuries for discussion of vascular and nerve injuries.

Compartment Syndrome
Compartment syndrome may occur following proximal tibial
physeal fractures because of mechanical blockage of the vascular
structures by a displaced fracture, damage to the popliteal artery, or
collateral damage to soft tissues at time of a large force injury. It
is important to remember in this injury that even a small posterior
displacement of the metaphysis may obstruct popliteal blood flow as the
artery is tethered anteriorly against the metaphysis by the anterior
tibial artery (see Fig. 23-17) Burkhart and Peterson25
reported a 12-year-old hurdler who sustained a closed Salter-Harris
type III injury that was treated with closed reduction and a long leg
cast. Increased pressure in both the anterior and posterior muscle
compartments caused narrowing of the terminal branches of the popliteal
artery, although arteriography showed that the popliteal artery itself
remained patent. Fasciotomies and a sympathectomy failed to save the
Growth Disturbance and Leg-Length Discrepancy
Similar to separations of the distal femoral epiphysis,
injuries to the proximal tibial epiphysis may cause shortening or
angulation from subsequent growth inhibition. This inhibition can occur
after all types of proximal tibial epiphyseal injuries. Anatomic
reduction with internal fixation reduces the risk of growth disturbance.140
The amount of angulation depends on the proximity of the area of growth
arrest to the periphery of the physis and the years left for growth
after injury. When partial or complete growth arrest is diagnosed, the
only methods to prevent progressive deformity are excision of an
epiphyseal bar or bilateral epiphysiodesis. Hemiepiphysiodesis will not
correct angular deformity when that deformity is caused by a bone
bridge. Early recognition and treatment of growth disturbance following
fracture may prevent the need for osteotomy. The proximal tibial physis
grows approximately 6 mm per year and growth ceases at approximately
age 14 in girls and 16 in boys.2,172
If complete growth arrest follows an epiphyseal separation at this
level and the patient is within 3 years of the end of growth, an
equalization procedure may be unnecessary. If more years of growth
remain, immediate epiphysiodesis of the opposite extremity may be
considered, or leg lengthening at a later stage may be indicated
depending on the expected final leg length discrepancy.
Knee Instability/Degenerative Changes
In a series of 10 patients with Salter-Harris types III and IV injuries, Poulsen et al.55 reported that two patients had symptomatic


instability and two additional patients had asymptomatic anterior
laxity. In the same series, degenerative changes were noted on x-rays
in two patients with varus deformity. Bertin and Goble15
reported eight cases of ligamentous laxity in 13 patients with proximal
tibial physeal fractures. Most other series do not report late
instability or degenerative changes, but this may be underreported for
type III and IV fractures.

Avulsion fracture of the tibial tuberosity are an
uncommon injury accounting for less than 1% of all epiphyseal injuries
and approximately 3% of all proximal tibial fractures in adults and
children.18,96,124 This injury is most commonly sustained by adolescents during sports activity.
Mechanism of Injury
Most acute traumatic avulsions of the tibial tubercle
occur in adolescents during jumping activities such as basketball, when
jumping is resisted, or during eccentric loading while landing.18,28,29,59,104,116 Tibial tuberosity fractures are reported almost exclusively in males.18,28,29,59,104,116
Avulsion of the tibial tubercle occurs when the patellar ligament
traction exceeds the combined strength of the physis and the supporting
soft tissues. During adolescence, quadriceps strength increases and
physeal stability decreases.21,91
There are two mechanisms of injury: violent contraction of the
quadriceps muscle against a fixed tibia, as occurs in resisted jumping,
and acute passive flexion of the knee against the contracted
quadriceps. A study of two adolescent gymnasts with tibial tuberosity
fractures found extension strength of the contralateral and injured
knee was greater than nonathletic controls and their gymnastic peers.
The authors hypothesized that the greater-than-usual strength of the
quadriceps was able to overcome the strength of the tibial tuberosity
or the physis.91
FIGURE 23-23 Type III tibial fracture with intra-articular extension. A. Lateral view demonstrates fracture and patella alta. B.
Fracture was treated with open reduction and internal fixation with one
7.3-mm cannulated screw. Alternatively, multiple smaller screws could
have been used.
Signs and Symptoms
Swelling and tenderness are centered over the anterior
aspect of the proximal tibia. Joint effusion and tense hemarthrosis may
be present. A freely movable triangular fragment of bone may be
palpated subcutaneously between the proximal tibia and the femoral
condyles. This fragment may have rotated so that the distal end
projects forward, tenting the overlying skin. The bed from which the
fragment was avulsed may be identified by a palpable defect on the
anterior aspect of the proximal tibia.
The amount of patella alta is proportional to the
severity of displacement of the tibial tubercle and may be as much as
10 cm. With a type I avulsion, the patient may be able to partially
extend the knee actively through the remaining soft tissue attachments.
Active extension is very impaired or impossible with types II and type
III injuries.
Radiographic Findings
Most patients with tibial tubercle fractures are
adolescents in whom the secondary ossification of the tibial tubercle
has developed. The best x-ray view to demonstrate displacement is a
lateral projection with the tibia rotated slightly internally because
the tubercle lies just lateral to the midline of the tibia. In this
projection, the size and degree of displacement of the fragment can be
identified more clearly. Two nondisplaced fragments may represent
normal ossification of the tibial tubercle since two or more secondary
ossification centers can be present as the tibial tubercle matures. A
smooth, horizontal nondisplaced radiolucent line through the tubercle
should not be confused with an epiphyseal fracture. Patella alta is
absent in normal knees and can indicate a displaced tibial tuberosity
avulsion fracture or distal pole patella sleeve fracture. The patella
will displace proximally the same distance as the tibial tuberosity is
displaced (Fig. 23-23). Patella alta17,165
may also help diagnose sleeve avulsion fractures of the tibial
tubercle, or patellar tendon ruptures, which have also been reported in

FIGURE 23-24
Probable mechanism of development of compartment syndrome after tibial
tubercle avulsion. The anterior tibial recurrent artery, and possibly
its branches, is torn and retracts into the anterior compartment
Associated Injuries
Proximal tibial tubercle avulsion fractures are
predisposed to development of compartment syndrome. The anterior tibial
recurrent artery near the base of the tibial tubercle may be avulsed
and bleed into the anterior compartment of the leg (Fig. 23-24).118 Severe pain greater than expected from this injury alone should raise suspicion of impending compartment syndrome.
Associated soft tissue injuries that have been reported
include patellar ligament and quadriceps tendon avulsions, collateral
and cruciate ligament tears, meniscal damage, and a lateral plateau rim
fracture.18,99,104,117 Avulsion of the anterior tibialis muscle has also been reported.76,175
Diagnosis and Classification
Avulsion fractures of the tibial tuberosity are
differentiated from Osgood-Schlatter disease by anatomic pathology and
clinical presentation. Osgood-Schlatter disease is a chronic traction
injury of the anterior ossicle of the tuberosity with no involvement of
the physis (Fig. 23-25). Ogden and Southwick116
observed new bone formation anterior to the secondary ossification
center in Osgood-Schlatter disease and concluded that the weak link in
Osgood-Schlatter disease is the attachment of the tendon to the
anterior surface of the tibial tubercle. In contrast, tibial tubercle
avulsions fail through the underlying physis, which is the posterior
surface of the tibial tubercle. A prospective study of Osgood-Schlatter
lesions evaluated with serial MRI, CT, and bone scans showed that the
most striking feature was soft tissue inflammation, not bony avulsion.135
An ossicle was seen anterior to the tibial tubercle in only one third
of the patients. There are clear differences in presentation as well.
Avulsion of the tibial tubercle occurs acutely with a specific injury,
whereas the patient with an Osgood-Schlatter lesion usually presents
with a gradual onset of symptoms characteristic of an overuse injury.
An adolescent with a displaced acute avulsion of the tibial tubercle is
immediately unable to stand or walk; however, an adolescent with
Osgood-Schlatter disease often tries to continue athletic activities
despite discomfort. There are several reports of acute tibial tubercle
avulsions patients with pre-existing Osgood-Schlatter disease,33,104,109,116
which has led to speculation that Osgood-Schlatter disorder may
predispose children to tibial tuberosity avulsion, but convincing
scientific evidence is absent and both conditions are prevalent in
adolescent male athletes.
FIGURE 23-25 Development of Osgood-Schlatter lesion. A.
Avulsion of osteochondral fragment that includes anterior surface
cartilage and a portion of the secondary ossification center of the
tibial tubercle. This may be clearly differentiated from a tibial
tuberosity fracture, which occurs along the apophysial cartilage. B. New bone fills in the gap between the avulsed osteochondral fragment and the tibial tubercle but does not disrupt the physis.
There is some overlap in reporting of tibial tuberosity
fractures that extend into the joint with Salter-Harris type III
separations of the anterior tibial epiphysis. For example, Shelton and
Canale144 and Burkhart and Peterson25
included tubercle avulsions in their reviews of proximal tibial physeal
separations. because the mechanism of injury, associated injuries, and
treatment of tibial tubercle avulsions with intra-articular extension
are more similar to tibial avulsion fractures than proximal tibial
epiphyseal fractures, we consider this type of fracture a tibial
tuberosity fracture.
Watson-Jones166 described three types of avulsion fractures of the tibial tubercle, with subsequent modifications by Ogden and associates116 who noted that the degree of displacement depends on the severity of injury to adjacent soft tissue attachments (Fig. 23-26). Ryu137 and Inoue72 proposed a type IV


fracture in which the physeal separation occurs through the tibial
tuberosity and extends posteriorly into the horizontal tibial physis.
Sleeve avulsion fractures of the tibial tuberosity extending over the
anterior metaphyseal area of the tibia have been described in four
children, aged 10 to 15 years.24,38
These injuries are similar to patellar sleeve fractures in that initial
x-rays may show no more than small subchondral fragments of bone. Open
reduction and fixation were recommended. We follow Davidson and Letts’38
recommendation that sleeve avulsion injuries of the tibial tubercle can
be added to the Watson-Jones system as a type V. Fractures may be
comminuted or have multiple fracture lines not easily classifiable

FIGURE 23-26 A.
Type I—the physeal separation occurs through the tubercle apophysis.
The fracture of tubercle is distal to the junction of the ossification
centers of the tibial tubercle and the proximal tibial epiphysis. B.
Type II—the physeal separation occurs through the tubercle apophysis.
The fracture extends anteriorly through the area bridging the
ossification centers of the tibial tubercle and the proximal tibial
epiphysis. C. Type III—the physeal
separation occurs through the tubercle apophysis. The fracture
propagates through the proximal tibial epiphysis into the knee joint
under the anterior attachments of the menisci. D.
Type IV—the physeal separation occurs through the tubercle apophysis
and propagates posteriorly through the horizontal proximal tibial
epiphysis. The fracture may exit posteriorly through the physis, as a
Salter-Harris type I equivalent, or through the metaphyseal, as a
Salter-Harris type II equivalent. E. Type
V—avulsion of a large area of periosteal attachment of the patellar
tendon associated with small subchondral fragments of bone. Not a true
physeal fracture.
Surgical and Applied Anatomy
Bony Anatomy
In its final adult form, the tibial tubercle is a bony
prominence on the anterior aspect of the proximal tibia. It lies
approximately one to two fingerbreadths distal to the proximal
articular surface of the tibia and forward of the anterior rim of the
proximal articular surface.
Ehrenborg43 divided
the postnatal development of the tibial tubercle into four stages. The
cartilaginous stage occurs before the secondary ossification center
appears and persists in girls until approximately 9 years of age and in
boys until 10 years of age. The apophyseal stage, in which the
ossification center appears in the tongue of cartilage, occurs between
8 and 12 years in girls and between 9 and 14 years of age in boys. The
epiphyseal stage, in which the secondary ossification centers coalesce
to form a tongue of bone continuous with the proximal tibial epiphysis,
occurs in girls between 10 and 15 years and in boys between 11 and 17
years of age. In the final bony stage, the epiphyseal line is closed
between the fully ossified tuberosity and the tibial metaphysis.
Soft Tissue Anatomy
The patellar ligament, which lies between the distal
pole of the patella and the tibial tubercle, is the terminal portion of
the powerful quadriceps muscle. During the apophyseal stage of
development of the tubercle, the patellar ligament inserts into an area
of cartilage proximal and anterior to the secondary ossification center
of the tubercle. The main attachment is in the proximal area of this
insertion zone between the secondary ossification centers of the
tubercle and the proximal tibial epiphysis. The fibrocartilaginous
tissue lying anterior to the secondary ossification center receives
only the distal part of the insertion. During the epiphyseal stage, the
patellar ligament inserts through fibrocartilage on the anterior aspect
of the downwardprojecting tongue of the proximal tibial epiphysis. The
inserting fibers merge distally into deep fascia after spanning the
physis. With traumatic avulsion of the tibial tubercle in this stage of
development, a broad flap of adjacent periosteum is attached to the
displaced fragment. In the final bony stage, the tendon fibers insert
directly into bone. After physiologic epiphysiodesis has occurred, the
tibial tubercle rarely is avulsed if the patient has normal bone.
Although the patellar ligament represents the main
insertion of the quadriceps muscle onto the leg beyond the knee joint,
it is reinforced by retinacular fibers radiating from the medial and
lateral margins of the patella obliquely down to the respective tibial
condyles. After traumatic avulsion of the tibial tuberosity, a limited
amount of active extension of the knee still is possible through the
retinacular extensions of the extensor mechanism. However, patella alta
and an extensor lag are present. The anatomic position of the tibial
tubercle is biomechanically important in terms of patellar tracking and
patellofemoral forces.
Vascular Anatomy
The tibial tubercle receives its main blood supply from
a plexus of arteries behind the patellar ligament at the level of the
attachment to the tibial tubercle.35 This vascular anastomosis arises from the anterior tibial recurrent artery and may be torn with this fracture.118,175
Several small branches extend down into the secondary ossification
center. A smaller part of the blood supply enters the superficial
surface of the tubercle from adjacent periosteal vessels.

Current Treatment Options
Nonoperative Treatment
Closed treatment is primarily reserved for nondisplaced
type I fractures. Persistence of even a small gap between the distal
end of the tubercle and the adjacent metaphysis may indicate an
interposed flap of periosteum.29,59
Minimally displaced, small avulsion fragments have been treated
successfully with immobilization in a cylinder cast or long-leg cast.28,29,104,116
The leg is positioned with the knee extended, but even with a long-leg
cast, a straight leg raise can place tension on the fracture. Molding
above the proximal pole of the patella has been suggested to help
maintain reduction.
Operative Treatment
Open reduction with fixation is recommended for tibial
tubercle avulsions that are intra-articular or displaced more than 2 to
3 mm.18,28,59,109
Residual displacement may lead to extensor lag and quadriceps weakness.
It may also be difficult to maintain reduction following closed
All type III fractures are intra-articular. For these
fractures, anatomic reduction with stable fixation is recommended by
several authors.28,29,104,116
A midline longitudinal incision is recommended to
facilitate any possible knee surgery in the future. The fracture bed is
carefully cleared of debris. A periosteal flap is frequently an
impediment to reduction.29,59
This is extracted and the fragment is reduced with the knee extended.
Screw fixation is used when the tuberosity fragment is large enough for
this type of fixation. The screw is inserted from anterior to posterior
but does not need to engage the posterior cortex when cancellous lag
screws are used. When there are 3 or more years of growth remaining or
when the fragment is too small for screw fixation, transfixing pins can
be used instead of screw fixation. Alternatively, a tension band can be
passed around the fragment or through the patellar ligament and fixed
through a drill hole across the anterior tibia distal to the attachment
of the tuberosity. Tension band wiring has also been reported as a
method to facilitate rapid rehabilitation in athletes.109
The wire is driven around the proximal pole of the patella or through a
drill hole in the distal pole and then looped distally through a
cannulated cortical screw that is inserted across the anterior tibia
distal to the patellar tendon insertion. This method may also be useful
when the fracture fragments are comminuted or too small for secure
fixation to the tibial metaphysis.
Sleeve avulsion fractures of the tuberosity can be challenging to stabilize because there is not a bone fragment for fixation.38 Davidson and Letts38
recommended fixation with small cancellous screws and heavy
nonabsorbable sutures to repair the torn retinaculum and periosteum.
Protection in a cast is recommended for 6 weeks because fixation
depends on soft-tissue stability.
Postoperative Management
Immobilization in a long-leg cast with the knee in 5 to
10 degrees of flexion is recommended for a period of 4 to 6 weeks.
Shorter periods of immobilization are used in younger adolescents when
fixation is secure. For large fragments that are securely fixed with
two or more screws, a knee immobilizer can be substituted for cast
immobilization. Range of motion and quadriceps strengthening are
initiated 6 weeks following injury.
Pearls and Pitfalls
  • Open reduction with internal fixation is recommended for almost all tibial tuberosity avulsion fractures.
  • There is an increased risk of compartment syndrome due to bleeding of the recurrent anterior tibial artery.
  • Recognition of sleeve avulsion fractures without bone may be difficult.
  • P.874
  • Use of a tourniquet may bind the quadriceps and hinder reduction of a displaced fracture.
  • Premature anterior physeal growth arrest may cause genu recurvatum that requires osteotomy for correction.119
FIGURE 23-27 A.
Lateral radiograph demonstrating a complex tibial tuberosity fracture
extending into the joint, as seen in a type III fracture, as well as
posterior along the physis and out the epiphysis. B. AP radiograph. C. Lateral view 3 months after surgery. D. AP view 3 months after surgery. (Courtesy of Robert Kay, MD.)

FIGURE 23-28
Type III tibial tuberosity avulsion in a 14-year-old girl sustained
while landing after a jump in basketball. This is a very common
mechanism of injury. A. Lateral view at injury. B. AP view at injury. C.
Lateral view following open reduction and internal fixation with
cannulated 4.5-mm screws. Note that screws are in compression with
threads not crossing the fracture site. There is no significant growth
left in this patient, so screw placement relative to the proximal
tibial physis was not of concern. D. AP
view of fixation. Note that screws are placed perpendicular to the
plane of the fracture, which often leads to the screws directed
Tibial tuberosity fractures have an excellent prognosis,
with few complications after reduction and surgical stabilization of
displaced fractures and closed management of nondisplaced
extra-articular fractures (Table 23-9). When
fractures unite in anatomic position, many series report no
complications other than prominent screws. Most patients return to full
athletic activity without residual sequelae within 3 to 6 months.42,52,61,64,120,176
Growth Disturbance
Premature closure of the tibial tubercle may lead to
genu recurvatum in a growing child. However, this complication is rare
because most of these injuries occur near the end of growth. If this
complication occurs, we recommend a proximal tibial osteotomy as
described by Pappas et al.119
Compartment Syndrome
Compartment syndrome has been reported in seven patients with displaced fractures, presumably because of tearing of the


anterior tibial recurrent vessels, which fan out at the tubercle but retract into the anterior compartment when torn.118,175
Close monitoring is recommended for all patients with displaced tibial
tuberosity avulsion fractures. Prophylactic anterior compartment
fasciotomy should be considered at the time of open reduction when the
anterior compartment is already swollen.18

TABLE 23-9 Complications of Tibial Tubercle Avulsion Fracture


Screw prominence


Compartment syndrome


Genu recurvatum, stiffness, refracture, thrombophlebitis

Prominent Screw Heads
Deep screw insertion or countersinking the screw heads
may be impossible without risking fracture of a tuberosity fragment.
Wiss et al.175 reported five of 15
patients with bursitis over prominent screw heads, four of whom had
6.5-mm screws. Overall, eight of the 15 patients underwent screw
removal. Fixation with small screws or use of a tension band may be an
alternative, but we recommend secure fixation even if prominent screws
may require secondary procedures for removal.
Other Complications
Loss of fixation can occur if the tuberosity fragment
fractures in the postoperative period. Cast immobilization is
recommended to reduce this risk unless fixation is securely placed into
a large tuberosity fracture fragment. Wiss et al.175
reported one refracture in a child who returned to sports 4 weeks after
injury. In one patient, a transverse proximal tibial fracture occurred
7 months postoperatively at the level of the retained screws.18 Recovery of motion and strength is rarely problematic. Christie and Dvonch29
reported a patient with persistent loss of 25 degrees of knee flexion
19 months after a type III injury. Patella alta can be expected if a
displaced tibial tubercle is not reduced adequately. Thrombophlebitis
has also been reported.116
Patellar fractures are much less common in children than
in adults, with estimates ranging from 1% to 6% of all patellar
fractures.92,132 Avulsion fractures of the patella are more common in children and may be difficult to diagnose.56,92
The sleeve fracture is unique to children and consists of a large
chondral fragment pulled from the ossification center with only a small
rim of bone attached (Fig. 23-29).47,65 In general, the treatment of patellar fractures in children is similar to treatment in adults.92,132
Mechanism of Injury
Fractures of the patella result from either a direct
blow, sudden contraction of the extensor mechanism, or a combination of
these direct and indirect forces. The patella is primarily in tension
when the quadriceps contracts with the knee in extension. However,
flexion produces compression and three-point bending forces on the
patella with the distal femur acting as a fulcrum (Fig. 23-30). The bending moment increases with increasing knee flexion.27 Thus, a direct blow with the knee in flexion is the most common mechanism for patellar fracture.27
A typical history is that the patient fell with the knee flexed or the
knee was struck while it was in a flexed position with the quadriceps
under tension. Fractures of the patella may also occur without a direct
blow when the quadriceps forcefully contracts with the knee flexed.
This is a more likely mechanism during jumping or other sports
activities,27,37 and injury is most likely to produce a transverse, sleeve, or other avulsion fracture.27,56 Comminuted fractures are most often the result of a high-energy direct blow such as motor vehicle trauma.27,37
In a young child, the patella is more flexible and adapts to
three-point bending or compression forces without breaking. The
patellar ossification center appears between the ages of 3 to 6 years,114,115 and patellar fractures have rarely been reported in patients younger than 8 years of age.
FIGURE 23-29
Sleeve fracture of the patella. A small segment of the distal pole of
the patella is avulsed with a relatively large portion of the articular
Another common mechanism of patellar fracture is
avulsion of medial osteochondral fragments in association with acute
patellar dislocation.108 This injury and its treatment are discussed in Chapter 24. Stress fractures of the patella have also been reported in children, but are rare.48 Grogan et.al.56
cautioned that avulsion fractures of the inferior pole of the patella
may be confused with Sindig-Larsen-Johanssen lesion, but acute onset or
separation of the distal fragment is more likely to indicate fracture.
Signs and Symptoms
The injured knee is swollen and tender, often with tense
hemarthrosis. Active knee extension is impaired and may be painful, and
weight-bearing is often impossible. Palpation may reveal a high-riding
patella or a palpable defect in the extensor mechanism. If the distal
pole is avulsed, voluntary contraction of the quadriceps muscle draws
the patella upward, but the patellar ligament remains lax. With
marginal avulsion fractures, there may be little more than tenderness
and localized swelling over the lateral or medial margin of the
patella, and a straight-leg


may be possible. An avulsion fragment adjacent to the medial margin of
the patella may indicate that an acute lateral dislocation of the
patella has occurred. The patella may have reduced spontaneously after
the injury. If dislocation has occurred, the apprehension test is
positive when the patient either resists passive manipulation by
contracting the quadriceps or may even grasp the examiner’s hand to
prevent further passive displacement. Pain at the lateral-superior
margin of the patella along with radiographic findings of a
nondisplaced fracture most likely represents a bipartite patella rather
than an acute fracture.54,115

FIGURE 23-30 A.
Incomplete transverse fracture of the patella. The articular cartilage
of the patella remains intact, but the fracture gaps anteriorly. B. Lateral radiograph shows incomplete transverse fracture of the patella.
X-ray Findings
Standard x-rays are usually sufficient to diagnose and
plan treatment for patellar fractures in children, but careful
attention should be paid to small flakes of bone that could represent
larger osteochondral avulsion fragments (see Fig. 23-29).9,81,170,171 When in doubt, MRI can help determine the nature and extent of injury.9
Transverse fractures are best seen on the lateral view. In a child, the
major fragments may tilt away from one another, with the maximal
separation anteriorly and minimal separation posteriorly.12
This may signify that the articular cartilage remains intact, even with
a complete fracture through the bony portion of the patella. The extent
of displacement may not be fully appreciated unless the knee is flexed
to 30 degrees when the x-ray is made.
Small flecks of bone adjacent to the distal pole may be
noteworthy. A symptomatic, small, visible radiodensity on the inferior
pole of the patella may represent a Sindig-Larsen-Johanssen lesion.
Displacement is more likely to indicate an acute fracture.49,56
Fragmentation or elongation of the distal pole associated with patella
alta in a child with cerebral palsy indicates long-standing extensor
mechanism stress.
The x-ray appearance of a sleeve fracture is often not
appreciated at first presentation to an emergency room. A barely
visible fleck of bone proximal to the patella may be the only x-ray
abnormality seen with a superior patellar sleeve fracture (Fig. 23-31). In an inferior patellar sleeve fracture, there may be patella alta in addition to a fleck of bone distal to the patella (Fig. 23-32).
Longitudinally oriented marginal fractures are best seen
on axial or skyline views. It is important to differentiate a medial
marginal fracture that traverses the entire thickness of the bone from
a medial tangential osteochondral fracture. CT scan may help
differentiate the two. An osteochondral fracture may include a
substantial amount of cartilage not visible on plain x-rays.
A bipartite patella is best seen on an AP x-ray, which
shows a crescent-shaped radiolucent line in the superolateral quadrant
of the patella and rounded margins of the accessory ossicle. If
symptoms are confusing, comparison x-rays of the opposite knee may be
helpful. A similar x-ray appearance of the contralateral patella
supports the diagnosis of bipartite patella.
Associated Injuries
Medial avulsion fractures of the patella may be
associated with lateral dislocation of the patella. Comminuted
fractures are more likely to be caused by high-energy trauma with
associated fractures of the tibia, femur, or pelvis.
Diagnosis and Classification
The greatest difficulty with fractures of the patella in
children is diagnosis of avulsion fractures with very small flakes of


Signs and symptoms of acute traumatic injury to the knee in the
presence of a flake of bone on standard x-rays generally indicate an
avulsion injury of some type. A high-riding patella without evidence of
bony fragments suggests a sleeve fracture of the inferior patella or
tibial tubercle. A palpable defect along the extensor mechanism or
inability to actively extend the knee is consistent with a patellar
fracture. Developmental anomalies may also be confused with fractures
especially when bipartite patellae are symptomatic. Bipartite patellae
are generally tender near the proximal lateral pole, which is the most
common location of an extra ossification center. Also, bipartite
patella is generally nondisplaced and is not associated with
hemarthrosis or loss of active knee extension. Sindig-Larsen-Johanssen
lesions may also be confused with distal pole avulsion injuries, but
these are chronic repetitive injuries with point tenderness as the
principle clinical finding.49,100 Acute injuries are more likely to demonstrate swelling and slight displacement of fragments on x-rays. Rosenthal and Levine136
found fragmentation of the distal pole of the patella in seven patients
with spastic cerebral palsy involving the lower extremities. They
believed that the fragmentation represented stress fractures caused by
excessive tension in the muscle associated with a flexed-knee gait.
Three of the fragmented patellae healed after hamstring lengthening.

FIGURE 23-31 A.
Lateral view of a child’s knee with a superior patella sleeve fracture.
The fracture was initially unrecognized at presentation. B. Two weeks later, ossification of the fracture is evident. Open reduction was necessary.
Patellar fractures are usually classified according to
morphology of the fracture pattern. Common categories of morphologic
classification are transverse, vertical, comminuted, osteochondral, and
sleeve.27 Grogan et al.56
classified avulsion fractures according to location of the avulsed
fragment into four categories: superior, inferior, medial, and lateral.
Classification for Management
We believe it is more useful to classify fractures as
nondisplaced and displaced. Other classifications may help understand
the fracture mechanism and diagnostic challenges, but nondisplaced
fractures are treated nonoperatively regardless of fracture pattern,
and displaced fractures require accurate reduction and stable fixation
regardless of fracture pattern.
Classification by Mechanism of Injury
Fracture pattern is influenced by the mechanism of
injury to some extent and may provide a more useful classification than
just description of the fracture morphology.27 The following classification is recommended for consideration as a combination of mechanism of injury and fracture pattern:
  • Comminuted Fractures are more likely to be caused by direct trauma.27 These are often nondisplaced, but direct trauma can produce damage to the articular contact area with poor outcomes.92
    Direct impact with comminution is also more likely to be present with
    open wounds or associated fractures of the femur tibia or pelvis.27,132
  • Transverse Fractures and Sleeve Fractures
    are the result of a combination of tension and three-point bend. This
    may occur during forceful contraction of the quadriceps with the knee
    flexed or with a blow to the patella with the knee flexed during
    quadriceps contraction. When the patella has a large ossification
    center, a transverse fracture through bone is more likely to occur from
    this mechanism; before the age of 13 years, sleeve fractures have been
    reported as the most common fracture pattern.37,47,132
    In this juvenile age group, the patella bends with transverse fracture
    of the cartilage followed by avulsion of the cartilage from the ossific
    nucleus. Thus, the outer shell is pulled off the ossification center


    the shell of a nut that is cracked transversely and pulled off the seed that remains inside the opposite half of the shell (see Figs. 23-29 and 23-32)
    A small bone fragment from the ossification center remains attached to
    the inside of the avulsed cartilage sleeve. The extent of injury is
    often not appreciated on initial x-rays. Inferior pole avulsion is the
    most common type.47,56,164,178 Superior pole avulsions are rare and more likely to be nondisplaced.56,164,178
    Small traumatic fractures of the superior and inferior poles of the
    patella should be distinguished from chronic repetitive stress injuries

  • Medial Avulsion Fractures are associated with lateral dislocation of the patella and are discussed in Chapter 24. These are best seen on axial x-rays of the patella such as the Merchant


    view with the knee flexed 45 degrees and the x-ray beam angled distally
    to intersect the knee at an angle of 30 degrees to the long axis of the
    Most medial avulsion fractures consist of small osteochondral
    fragments, but large vertical sleeve fractures or vertical fractures of
    the patella may also occur.56

FIGURE 23-32 An inferior patella sleeve fracture. A. On lateral view, ossific fragment is difficult to appreciate. Patella alta may be noted. B. On AP view, ossific fragment can fortunately be seen within the joint space. C. On examination, defect is palpable in between the patella and patella tendon. D. Intraoperative exposure. E. Repair of transverse retinacular tears and patella sleeve fracture with sutures. (Courtesy of Robert Kay, MD.)
Surgical and Applied Anatomy
Bony Anatomy
At birth, the shape of the patella is well defined in
cartilage form. Ossification of the cartilaginous anlage begins between
3 and 6 years of age.114,115
Often, there is more than one central ossicle, and there may be as many
as six irregular centers. Gradually, the ossicles coalesce and
ossification proceeds peripherally until all cartilage except the
articular surface is replaced by bone. Until ossification is complete,
the edges of the enlarging ossific nucleus may appear irregular. The
pattern of bony development is similar in this respect to the growing
epiphysis of the distal femur (Fig. 23-33).
Ossification of the patella usually is complete by the beginning of the
second decade. Internal fixation of the patella at any age does not
retard growth because the patella enlarges by appositional growth
through intramembranous ossification without a discrete physis.
The patella may be bipartite or multipartite.115,180
The overall incidence of bipartite patella in adolescents is reported
to be 2% to 15%, but that may include accessory ossification centers
instead of discrete bipartite patella in older adolescents.115
The true incidence of well-formed bipartite patella is probably much
lower than 2%. The most common location of the bipartite segment is the
superolateral pole of the patella.54,115
FIGURE 23-33 Normal knee in a 6-year-old child. Note irregular ossification of the patella and the distal femoral condyle.
Congenital absence14 and congenital hypoplasia6
of the patella are uncommon. Although these variations in development
have been reported as isolated findings, they can also occur as part of
the hereditary symptom complex onycho-osteodysplasia or nail-patella
Vascular Anatomy
Scapinelli141 studied the blood supply to the human patella in specimens ranging from birth to old age. Neither he141 nor Crock35
noted differences between immature and mature specimens except for the
intraosseous arborization that occurs in the ossification center. An
anastomotic circle surrounds the patella with contributions from the
paired superior and inferior geniculate arteries, as well as the
anterior tibial recurrent artery. From the anastomotic ring, branches
converge centripetally toward the anterior surface of the patella and
enter through foramina in the middle third of this surface. Additional
blood supply to the patella enters the distal pole behind the patellar
ligament. Thus, virtually the entire blood supply to the patella comes
from the anterior surface or distal pole, with essentially no
penetration of vessels from the medial, proximal, or lateral margins of
the patella. Scapinelli141 noted
that these findings correlate with the fact that marginal fractures of
the patella are more likely to progress to nonunion. Also, injury to
blood vessels entering the anterior aspect of the patella may lead to
osteonecrosis of the proximal pole.141
Also, osteochondrosis and posttraumatic disturbance of ossification
have been reported that may indicate ischemia following trauma.105,127
Current Treatment Options
Closed treatment is recommended for nondisplaced
fractures. Aspiration of a tense hemarthrosis may relieve pain. A
cylinder cast in extension is applied, and progressive weight-bearing
is permitted. Immobilization may be continued for 6 weeks.
Indications for surgical stabilization of patellar
fractures in children are essentially the same as for patellar
fractures in adults.37,92,132
Restoration of the extensor function and articular congruity is
essential. This requires accurate reduction and stabilization of
fracture fragments. Repair of torn retinaculum is also recommended,168 although percutaneous fixation with excellent outcomes has been reported in adults.90,156,163
An inability to actively extend the knee fully suggests major
disruption of the retinaculum and may be an indication for open repair.
Operative Repair
Fixation techniques include a circumferential wire loop,
nonabsorbable sutures through longitudinally drilled holes or
cannulated screws, the tension-band technique, and screws or pins
without tension band fixation. Choice of fixation is determined by the
fracture pattern. Displaced transverse fractures, including sleeve
fractures, are the most common type requiring internal fixation. An
experimental study by Weber et al.168 supported fixation by modified tension-band wiring. The method tested by Weber et al.168
consisted of a wire loop passed transversely behind the tips of two
longitudinal fixation wires and then tensioned as a longitudinal oval
over the anterior surface of the patella. The AO group popularized a
variation by crossing the tension band in a longitudinal
figure-of-eight on the anterior surface of the patella (Fig. 23-34) Carpenter et al.27 studied


several methods of fixation and determined that the strongest repair
was provided by two longitudinal cannulated screws with a tension band
wire passed through the central holes and twisted in a figure-of-eight
over the anterior surface of the patella. This forms a horizontal
figure-of-eight instead of a vertical figure-of-eight. In 2007, John et
tested different orientations of the figure-of-eight and determined
that the horizontal figure-of-eight with two twists of wire at adjacent
corners provided the greatest interfragmentary compression and
stability (Fig. 23-35). Braided wire or braided
polyester suture can also be used instead of stainless steel wire.
Absorbable suture has also been successfully used in a child.155 Fortunately, children heal rapidly


and tolerate immobilization, so the technique of wiring may not be as important in children as it is in adults.

FIGURE 23-34 A. Displaced transverse fracture of the patella. B,C.
After open reduction and internal fixation with tension-band technique
using figure-of-eight wire over parallel longitudinal pins. This case
with steel wire was chosen to illustrate the technique. The authors
prefer using heavy suture to possibly avoid the need for future
hardware removal.
FIGURE 23-35
Four configurations of tension band loops. When stainless steel wire is
used, configuration “D” provides greater interfragmentary compression
and stability. A. Vertical figure-of-eight with one wire twist. B. Vertical figure-of-eight with two wire twists. C. Vertical figure-of-eight with two wire twists placed at adjacent corners. D.
Horizontal figure-of-eight with two wire twists placed at adjacent
corners. Method “D” can be achieved with two cannulated compression
screws for added stability. (Reprinted with permission from John J,
Wagner WW, and Kuiper JH. Tension-band wiring of transverse fractures
of the patella. Intl Orthop 2007;31:703-707.)
Medial avulsion fractures associated with acute patellar
dislocation should be repaired to reduce the risk of recurrent
instability.56,134 The osteochondral fragment is either removed or repaired depending primarily on the size of the avulsed fragment.56,129
When larger than 1 cm, the fragment can usually be securely replaced
and fixed with pins, headless screws, sutures, or resorbable fixation
devices.13,56,97,129 Rorabeck and Bobechko134
advised repairing the extensor apparatus in children when osteochondral
fractures are associated with patellar dislocation. Repair was
successful with or without excision of the osteochondral fragment.134 A more detailed discussion of this injury can be found in Chapter 24.
Comminuted fractures may be difficult to reduce and
stabilize. Comminution may produce fragments that are small or
detached. Cerclage wiring with small fragment fixation may allow
restoration of extensor function and articular congruity. Partial
patellectomy may be necessary, but total patellectomy should be avoided
if at all possible.27,37,92,132
Preservation of some of the articular surface is preferred to total
patellectomy. When partial patellectomy is necessary, the quadriceps
tendon or patellar tendon is pulled to the remnant of patella and
sutured as close as possible to the articular surface through drill
holes to minimize the step-off between the tendon and articular margin
of the patellar fragment. On the rare occasion when total patellectomy
is unavoidable, transverse closure is preferred to longitudinal closure
of the defect in the extensor mechanism.77
Pearls and Pitfalls
  • Late recognition of patellar sleeve
    fractures is not uncommon—this diagnosis should be considered in any
    patient who does not have full active extension of the knee.
  • When repairing the retinaculum, all the
    sutures are placed first without tying them. If the sutures are tied as
    they are placed, it becomes increasingly difficult to visualize the
    torn retinaculum and fracture.
  • If closing the gap of the extensor mechanism is difficult:
    • The tourniquet, which may be tethering the quadriceps, can be released.
    • If the fracture is not acute, quadriceps
      contraction may have occurred, in which case judicious musculotendinous
      lengthening of the quadriceps complex may be needed.
Early complications include fracture displacement and
wound complications. These may be due to the magnitude of the initial
trauma, technical deficiencies, or patient noncompliance. Repeat
fixation is recommended when secondary displacement is more than 3 to
4-mm of gap or more than 2 mm of step-off of the articular surface.
Late complications include joint stiffness,
patellafemoral pain, and weakness. Fortunately, these are rare in
children when accurate reduction of the fracture is obtained and
maintained until union. Early gentle motion beginning 4 weeks after
surgery, with later strengthening exercises, can diminish the risk of
weakness or limited motion. Delayed diagnosis of sleeve fractures of
the patella is not uncommon.47,65,178
Repair with deébridement and approximation of the fracture fragments
has been reported as late as 2 months, although loss of knee flexion
may be a result.178 It is best to
avoid quadriceps lengthening at the time of repair even if knee
extension is required to approximate the fragments. Quadriceps
lengthening can be done at a later time if satisfactory flexion cannot
be achieved. Manipulation should be avoided because of the risk of
distal femoral physeal separation during manipulation under anesthesia.
In particular, sleeve fractures if unrecognized or inadequately reduced and fixed can lead to extensor lag.84,116
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