Intra-Articular Injuries of the Knee

Fractures of the tibial eminence occur due to
chondroepiphyseal avulsion of the anterior cruciate ligament (ACL)
insertion on the anteromedial tibial eminence.²³²,³¹¹ Tibial eminence fractures were once thought to be the pediatric equivalent of midsubstance ACL tears in adults.³⁰,³⁶,⁶¹,¹²⁰,¹⁴⁸,¹⁷⁶,¹⁸⁸,²⁰⁰,²⁰¹,²³⁶,²⁴⁰,³⁰⁷,³⁰⁸

Avulsion fracture of the tibial spine is a relatively uncommon injury in children: Skak et al.²⁷³
reported that it occurred in 3 per 100,000 children each year. The most
common causes of these fractures are bicycle accidents and athletic
activities.²¹⁷

Historically, treatment has evolved from closed
treatment of all fractures to operative treatment of certain fractures.
Garcia and Neer¹⁰⁷ reported 42
fractures of the tibial spine in patients ranging in age from 7 to 60
years, 6 of whom had positive anterior drawer signs indicating
associated collateral ligament injuries. They reported successful
closed management in half their patients. Meyers and McKeever,²¹⁶
however, recommended arthrotomy and open reduction for all displaced
fractures, followed by cast immobilization with the knee in 20 degrees
of flexion rather than hyperextension, believing that hyperextension
aggravated the injury in one of their patients. Gronkvist et al.¹²⁰
reported late instability in 16 of 32 children with tibial spine
fractures, and recommended surgery for all displaced tibial spine
fractures, especially in children older than 10 years because “the
older the patient, the more the demand on the anterior cruciate
ligament-tibial spine complex.”¹²⁰ Baxter and Wiley³⁰ noted mild to moderate knee laxity at follow-up in 45 patients, even after anatomic reduction of the tibial spine. McLennan²¹²
reported 10 patients with type III intercondylar eminence fractures
treated with closed reduction and with arthroscopic reduction with or
without internal fixation.

At
second-look arthroscopy 6 years after the initial injury, those treated
with closed reduction had more knee laxity than those treated
arthroscopically.

Modern treatment is based on fracture type. Nondisplaced
fractures and hinged or displaced fractures which are able to be
reduced can be treated closed. Hinged and displaced fractures which do
not reduce require open or arthroscopic reduction with internal
fixation. A variety of treatment options have been reported including
cast immobilization,¹⁸⁸,²²³ closed reduction with immobilization,²³⁶,³⁰⁸ open reduction with immobilization,²²³ open reduction with internal fixation,²²⁵,²³⁶ arthroscopic reduction with immobilization,²¹² arthroscopic reduction with suture fixation,⁴⁹,¹³⁷,¹⁵⁵,¹⁸⁸,²⁰⁰,²⁰¹ and arthroscopic reduction with wire,²⁷ screw fixation,³⁶,¹⁸⁸,²¹² anchor fixation,²⁹⁸ and bioabsorbable fixation.²⁶⁴

The prognosis for closed treatment of nondisplaced and
reduced tibial spine fractures and for operative treatment of displaced
fractures is good. Most series report healing with an excellent
functional outcome despite some residual knee laxity.²⁷,³⁰,³⁶,¹⁵⁵,¹⁷⁰,¹⁸⁸,¹⁹⁵,²⁰⁰,²⁰¹,²¹¹,²¹²,²²³,²²⁵,²⁷⁶,³⁰⁷,³⁰⁸ Potential complications include nonunion, malunion, arthrofibrosis, residual knee laxity, and growth disturbance.²⁷,³⁰,³⁶,¹⁵⁵,¹⁷⁰,¹⁸⁸,²⁰⁰,²⁰¹,²¹¹,²¹²,²²³,²²⁵,²⁷⁶,²⁹⁶,³⁰⁸

The intercondylar eminence is that part of the tibial
plateau lying between the anterior poles of the menisci forward to the
anterior tibial spine. It is triangular, with its base at the anterior
border of the proximal tibia. In the immature skeleton, the proximal
surface of the eminence is covered entirely with cartilage. The ACL
attaches distally to the anterior tibial spine with separate slips
anterior and lateral as well (Fig. 24-4). The
ligament originates off the posterior margin of the lateral aspect of
the intercondylar notch. The anterior horn of the lateral meniscus is
typically attached in the region of the intercondylar eminence at the
ACL insertion. In 12 patients with displaced tibial spine fractures
which did not reduce closed, Lowe et al.¹⁹⁶
reported that the anterior horn of the lateral meniscus consistently
remained attached to the tibial eminence fracture fragment. The
posterior cruciate ligament (PCL) originates off the medial aspect of
the intercondylar notch and inserts on the posterior aspect of the
proximal tibia, distal to the joint line.

Meniscal or intermeniscal ligament entrapment under the
displaced tibial eminence fragment has been reported and may be a
rationale for considering arthroscopic or open reduction in displaced
tibial spine fractures (Fig. 24-5).⁵⁴,⁵⁹,⁹⁴,¹⁷⁷
Meniscal entrapment prevents anatomic reduction of the tibial spine
fragment, which may result in increased anterior laxity or a block to
extension.¹²⁰,¹⁴⁸,²¹¹,²³⁶,²⁴⁰ Furthermore, meniscal entrapment itself may cause knee pain after fracture healing.⁵⁹ Falstie-Jensen and Sondergard Petersen,⁹⁴ Burstein and colleagues,⁵⁴ and Chandler and Miller⁵⁹
have all reported cases of meniscal incarceration blocking reduction of
type 2 or 3 tibial spine fractures in children. The prevalence of
meniscal entrapment in tibial spine fractures may be common for
displaced fractures. As aforementioned, the anterior horn of the
lateral meniscus typically remains attached to the tibial eminence
fracture fragment. However, the anterior horn of the medial meniscus or
the intermeniscal ligament may become incarcerated. Mah and colleagues²⁰⁰
found medial meniscal entrapment preventing reduction in 8 of 10
children with type 3 fractures undergoing arthroscopic management. In a
consecutive series of 80 skeletally immature patients who underwent
surgical fixation of hinged or displaced tibial eminence fractures
which did not reduce in extension, Kocher et al.¹⁷⁷
found entrapment of the anterior horn medial meniscus (n = 36),
intermeniscal ligament (n = 6), or anterior horn lateral meniscus (n =
1) in 26% (6/23) of hinged (type 2) fractures and 65% (37/57) of
displaced (type 3) fractures. The entrapped meniscus can typically be
extracted with an arthroscopic probe and retracted with a retaining
suture (Fig. 24-6).

Treatment options include including cast immobilization,¹⁸⁸,²²³ closed reduction with immobilization,²³⁶,³⁰⁸ open reduction with immobilization,²²³ open reduction with internal fixation,²²⁵,³⁰⁸ arthroscopic reduction with immobilization,²¹² arthroscopic reduction with suture fixation,¹³⁷,¹⁵⁵,¹⁸⁸,²⁰⁰,²⁰¹ and arthroscopic reduction with wire,²⁷ screw fixation,³⁶,¹⁸⁸,²¹² anchor fixation,²⁹⁸ and bioabsorbable fixation.²⁶⁴
Studies of the biomechanical strength of internal fixation suggest
similar fixation strength between bioabsorbable and metallic internal
fixation²⁰² and increased fixation strength of suture fixation over internal fixation.⁸⁷,²⁰²

Closed treatment is typically utilized for type 1
fractures and for type 2 or 3 fractures that reduce closed. Closed
reduction is usually performed after aspiration of the hematoma with
placement of the knee in full extension or 20 to 30 degrees of flexion.
Radiographs are utilized to assess adequacy of reduction. If the
fracture fragment extends into the medial or lateral tibial plateaus,
extension may affect a reduction through pressure applied by medial or
lateral femoral condyle congruence (Fig. 24-7).
Fractures confined within the intercondylar notch, however, will not
reduce in this manner. Portions of the ACL are tight in all knee
flexion positions; therefore, there may not be any one position without
traction being applied by the ACL. Interposition of the anterior horn
medial meniscus or intermeniscal ligament may further block reduction.

Closed reduction can be successful for some type 2 fractures, but is infrequently successful in type 3 fractures. Kocher et al.¹⁷⁷ reported successful closed reduction in approximately 50% of type 2 fractures (26/49). However, no type 3 fractures were able

to be close reduced (0/57). Bakalim and Wilpulla²⁶ reported successful closed reduction in 10 patients. Smillie²⁷⁵ suggested that closed reduction by hyperextension can be accomplished only with a large fragment. Meyers and McKeever²¹⁶
recommended cast immobilization with the knee in 20 degrees of flexion
for all type I and II fractures and open reduction or arthroscopic
treatment of all type III fractures.

Arthroscopic or open reduction with internal fixation of
type 2 and 3 tibial eminence fractures which do not reduce has been
advocated because of the potential for meniscal entrapment under the
fractured tibial eminence preventing anatomic closed reduction,⁵⁴,⁵⁹,⁹⁴,²⁰⁰ the potential for instability and loss of extension associated with closed reduction and immobilization,¹²⁰,¹⁴⁸,²¹¹,²³⁶
the ability to evaluate and treat associated intra-articular meniscal
or osteochondral injuries, and the opportunity for early mobilization.
For displaced fractures, Wiley and Baxter³⁰⁷ found a correlation between fracture displacement at healing with knee laxity and functional outcome.

The prognosis for closed treatment of nondisplaced and
reduced tibial spine fractures and for operative treatment of displaced
fractures is good. Most series report healing with an excellent
functional outcome despite some residual knee laxity.²⁷,³⁰,³⁶,¹⁷⁰,¹⁸⁸,²⁰⁰,²⁰¹,²¹¹,²¹²,²²³,²²⁵,²⁷⁶,³⁰⁷,³⁰⁸ Potential complications include nonunion, malunion, arthrofibrosis, residual knee laxity, and growth disturbance.²⁷,³⁰,³⁶,¹⁷⁰,¹⁸⁸,²⁰⁰,²⁰¹,²¹¹,²¹²,²²³,²²⁵,²⁷⁶,³⁰⁷,³⁰⁸

Mild residual knee laxity is seen frequently, even after
anatomic reduction and healing of tibial eminence fractures. Baxter and
Wiley³⁰,³⁰⁷
found excellent functional results without symptomatic instability in
17 pediatric knees with displaced tibial spine fractures, despite a
positive Lachman examination in 51% of patients and increased mean
instrumented knee laxity of 3.5 mm. After open reduction and internal
fixation of type III fractures in 13 pediatric knees, Smith²⁷⁶
found instability symptoms in only 2 patients despite a positive
Lachman exam in 87% of patients. In a group of 50 children after closed
or

open treatment, Willis and coworkers³⁰⁸
found excellent clinical results despite a positive Lachman exam in 64%
of patients and instrumented knee laxity of 3.5 mm for type II
fractures and 4.5 mm for type III fractures. Similarly, Janarv et al.¹⁴⁸ and Kocher et al.¹⁷⁰ found excellent functional results despite persistent laxity even in anatomically healed fractures.

Persistent laxity despite anatomic reduction and healing
of tibial spine fractures in children is likely related to plastic
deformation of the ACL with tibial spine fracture. At the time of
tibial spine fixation, the ACL often appears hemorrhagic within its
sheath, but grossly intact and in continuity. In a primate animal
model, Noyes and coworkers²³² found
frequent elongation and disruption of ligament architecture despite
gross ligament continuity in experimentally produced tibial spine
fractures at both slow and fasting loading rates. This persistent
anteroposterior laxity despite anatomic reduction may be avoided by
countersinking the tibial spine fragment within the epiphysis at the
time of reduction and fixation. However, ACL injury after previous
tibial spine fracture is rare.

Poor results may occur after type eminence fractures associated

with unrecognized injuries of the collateral ligaments or complications from associated physeal fracture.²¹⁵,²⁷⁶,²⁸⁶
In addition, hardware across the proximal tibial physis may result in
growth disturbance with recurvatum deformity or shortening.²²⁶

Malunion of type 2 and 3 fractures may cause mechanical impingement of the knee during full extension (Fig. 24-12).¹⁰⁶,²⁰⁰,²⁰¹
For symptomatic patients, this can be corrected by excision of the
manumitted fragment and anatomic reinsertion of the ACL. Alternatively,
excision of the fragment and ACL reconstruction can be considered in
adults and older adolescents.

Nonunion of type 2 and 3 tibial spine fractures treated
closed can usually be managed by arthroscopic or open reduction with
internal fixation.¹⁶¹,¹⁹⁴,²⁹⁶
Technically, débridement of the fracture bed and the fracture fragment
to fresh, bleeding bone is essential to optimize bony healing. Bone
graft may be required in cases of chronic nonunion. Again, excision of
the fragment and ACL reconstruction can be alternatively be considered
in adults and older adolescents.

Stiffness and arthrofibrosis can be a challenging
problem after both nonoperative and operative management of tibial
eminence fractures. The milieu of a major traumatic intra-articular
injury, a large hemarthrosis, and immobilization can predispose to
arthrofibrosis. Avoidance of cast immobilization with early
mobilization utilizing physical therapy can minimize the risk of
arthrofibrosis. Dynamic splinting and aggressive physical therapy can
be employed during the first 3 months from fracture if stiffness is
present. If significant stiffness remains after 3 months from fracture,
patients should be managed with manipulation under anesthesia and
arthroscopy with lyses of adhesions. Overly vigorous manipulation
should be avoided in order to avert iatrogenic proximal tibial or
distal femoral physeal fracture.

Osteochondral fractures in skeletally immature patients
are more common than once thought. They are typically associated with
acute lateral patellar dislocations. The most common locations for
these fractures are the medial patellar facet or the lateral femoral
condyle (Fig. 24-13). The osteochondral
fracture fragments may range from small incidental loose bodies to
large portions of the entire articular surface. The prevalence of
osteochondral fractures associated with acute patella dislocation
ranges from 25% to 50%.¹³,⁴³,⁹⁵,²⁰⁶,²²⁹,²⁸² Matelic et al.²⁰⁶ found 67% of children presenting with an acute hemarthrosis of the knee had an osteochondral fracture.

The diagnosis can be difficult because even a large
osteochondral fragment may contain only a small ossified portion that
is visible on plain radiographs. MRI may be useful in identifying
associated osteochondral fractures in cases of traumatic patellar
dislocation. Acute osteochondral fractures must be differentiated from
acute chondral injuries, which do not involve subchondral bone, and
osteochondritis dissecans,¹⁰⁰,¹⁷⁸
which is a repetitive overuse lesion of the subchondral bone that may
result in a nonhealing stress fracture that can progress to fragment
dissection.

Treatment of osteochondral fractures includes removal of
small loose bodies and fixation of larger osteochondral fragments. In
cases associated with patellar dislocation, lateral retinacular
release, medial retinacular repair, and medial patellofemoral ligament
repair may be performed adjunctively.

The patella tracks in the intercondylar notch between
the medial and lateral femoral condyles during flexion and extension of
the knee.¹¹³,¹⁴²
With increasing knee flexion, the contact area on the articular surface
of the patella moves to the proximal patella. Between 90 and 135
degrees of flexion, the patella glides into the intercondylar notch
between the femoral condyles. The two primary areas of contact are the
medial patellar facet with the medial femoral condyle and the
superolateral quadrant of the lateral patellar facet with the lateral
femoral condyle. Soft tissue support for the patellofemoral joint
includes the quadriceps muscle, the medial patellofemoral ligament, the
patellar tendon, and the vastus medialis and lateralis muscles.

Dislocation of the patella may tear the medial retinaculum,

but the rest of the quadriceps muscle-patellar ligament complex
continues to apply significant compression forces as the patella
dislocates laterally. These forces are believed to cause fracture of
the medial patellar facet, the lateral femoral condyle articular rim,
or both (see Fig. 24-13).¹⁶⁰,²³⁴,²⁵⁴
Osteochondral fractures are uncommon with chronic recurrent subluxation
or dislocation of the patella because of laxity of the medial
retinaculum and lesser compressive forces on the patella and the
lateral femoral condyle.

A histopathologic study by Flachsmann et al.⁹⁸
helped to explain the occurrence of osteochondral fractures in the
skeletally immature at a ultrastructural level. They noted that in the
joint of a juvenile, interdigitating fingers of uncalcified cartilage
penetrate deep into the subchondral bone providing a relatively strong
bond between the articular cartilage and the subchondral bone. In the
adult, the articular cartilage is bonded to the subchondral bone by the
well-defined calcified cartilage layer, the cement line. When shear
stress is applied to the juvenile joint, the forces are transmitted
into the subchondral bone by the interdigitating cartilage with the
resultant bending forces causing the open pore structure of the
trabecular bone to fail. In mature tissue, the plane of failure occurs
between the deep and calcified layers of the cartilage, the tidemark,
leaving the osteochondral junction undisturbed. Although the juvenile
and adult tissue patterns are different, they both provide adequate
fracture toughness to the osteochondral region. As the tissue
transitions, however, from the juvenile to the adult pattern during
adolescence, the fracture toughness is lost. The calcified cartilage
layer is only partially formed and the interdigitating cartilage
fingers are progressively replaced with calcified matrix. Consequently,
the interface between the articular cartilage and the subchondral bone
becomes a zone of potential weakness in the joint which may explain why
osteochondral fractures are seen frequently in adolescents and young
adults.

The recommended management of acute osteochondral
fractures of the knee is either surgical removal of the fragment or
fixation of the fragment.¹⁷⁶

If the lesion is large (>1 cm), easily accessible,
involves a weight-bearing area, and has adequate cortical bone attached
to the chondral surface, then fixation should be attempted.¹¹³,¹⁶⁰,²⁷⁶,²⁸¹,³¹⁰,³¹¹
This can be done via arthroscopy or arthrotomy. Fixation options
include Kirschner wires, Steinmann pins, cannulated screws, and
variable pitch headless screws. Hardware removal is typically performed
after fracture healing. Lewis and Foster¹⁹⁰
reported good results in eight osteochondral fractures after fixation
with Herbert bone screws without need for hardware removal. More
recently, bioabsorbable fixation devices are available which may
eliminate the need for hardware removal.

If the fracture fragment is small (<1 cm), chronic,
or from a non-weight-bearing region of the knee, then removal of loose
bodies is recommended.⁹,¹⁴¹,¹⁴⁹,²⁵⁴,²⁶³
The fragment’s crater should be débrided to stable edges, and the
underlying subchondral bone should be perforated to encourage
fibrocartilage formation.

In patients with an osteochondral fracture after acute patellar

dislocation, concomitant repair of the medial retinaculum and medial
patellofemoral ligament at the time of fragment excision or fixation
may decrease the risk of recurrent patellar instability.⁶⁴,²⁵³

Osteochondral fractures with small fragments not
involving the weight-bearing portion of the joint usually have a good
prognosis after removal of loose bodies.

The prognosis for larger osteochondral fractures
involving the weight-bearing surfaces is more variable. Excision of
large fragments involving the weight-bearing articular surfaces
predictably leads to the development of degenerative changes.¹⁶

Fracture fixation resulting in fragment healing with a congruous
articular surface offers the best long-term prognosis; however, even
these cases may develop crepitus, stiffness, and degenerative changes.⁸

Complications include recurrent patellar instability
with further osteochondral injury after both excision of loose bodies
and fracture fixation. Concomitant medial patellofemoral ligament
repair appears to decrease the risk of recurrent instability.²⁹,²⁵³
Stiffness may occur, particularly after fracture fixation. Adequate
internal fixation is necessary to allow for early motion, which
decreases the risk of loss of motion. Stiffness may be treated with
aggressive therapy and dynamic splinting during the first 3 to 4 months
after injury. Beyond this time frame, manipulation under anesthesia
with arthroscopic lysis of adhesions is typically required. Nonunion
after fragment fixation may also occur, necessitating further attempts
at fracture fixation or fracture excision. Excision of larger
osteochondral fractures involving the weight-bearing articular surfaces
requires associated chondral resurfacing, such as marrow stimulation
procedures (microfracture), osteochondral grafting (mosaicplasty),

or autologous chondrocyte implantation.³⁴,³⁸,²⁴²,²⁸³
Complications related to hardware for fracture fixation may also occur.
Proud screw heads may scuff articular surfaces. Bioabsorbable implants
may result in synovitis with sterile effusions.

Patellar instability is relatively common in children if
all subluxations and dislocations from varying causes are considered.
Patellar instability involves cases ranging from acute, traumatic
patellar dislocation to chronic, recurrent patellar subluxation in a
patient with ligamentous laxity.

Acute, traumatic patellar dislocation typically occurs
in adolescents. Acute patellar dislocations in younger children usually
occur in the context underlying patellofemoral dysplasia.²¹³
Chronic, atraumatic, recurrent patellofemoral instability occurs most
often in adolescent females, with underlying laxity and alignment risk
factors.

Acute, traumatic patellar dislocations without
associated osteochondral fracture are treated with a short period of
immobilization followed by patellofemoral bracing and rehabilitation.
Acute, traumatic patellar dislocations with osteochondral fractures are
treated as discussed in the previous section with removal of loose
bodies or fracture fixation. Chronic, recurrent, atraumatic
patellofemoral instability is typically treated with patellofemoral
bracing, rehabilitation, and orthotics if needed. Recurrent
patellofemoral instability which has been recalcitrant to nonoperative
treatment can be managed with a variety of proximal and distal
realignment procedures.

The patella is a sesamoid bone in the quadriceps
mechanism. As the insertion site of all muscle components of the
quadriceps complex, it serves biomechanically to provide an extension
moment during range of motion of the knee joint. The trochlear shape of
the distal femur stabilizes the patella as it tracks through a range of
motion. The hyaline cartilage of the patella is the thickest in the
body.

At 20 degrees of knee flexion, the inferior pole of the
patella contacts a relatively small area of the femoral groove. With
further flexion, the contact area moves superiorly and increases in
size. The medial facet of the patella comes in contact with the femoral
groove only when flexion reaches 90 to 130 degrees.

The average adult trochlear femoral groove height is 5.2
mm and lateral femoral condyle height is 3.4 mm. The patellar articular
cartilage is 6 to 7 mm deep, the thickest articular cartilage in the
body and a reflection of the joint’s inherent incongruity. The usual
normal lateral alignment of the patella is checked by the medial
quadriceps expansion and focal thickening of the capsule in the areas
of the medial patellofemoral and medial meniscopatellar ligaments.⁷⁸
Dynamic stability depends on muscle forces, primarily the quadriceps
and hamstrings acting through an elegant lower extremity articulated
lever system that creates and modulates forces during gait. The
quadriceps blends with the joint capsule to provide a combination of
dynamic and static balance. Tightness or laxity of any of the factors
involved with maintenance of the balance leads to varying levels of
instability. Acute patellar dislocation almost always is in a lateral
direction unless it is due to a medially oriented direct blow or
follows over vigorous lateral retinacular release. Sallay et al.²⁵⁹
demonstrated avulsions of the medial patellofemoral ligament from the
femur in 94% (15 of 16) of patients during surgical exploration after
acute patellar dislocation. Desio et al.,⁷⁸
using a cadaveric serial cutting model, found that the medial
patellofemoral ligament provided 60% of the resistance to lateral
patellar translation at 20 degrees of knee flexion. The medial
patellomeniscal ligament accounted for an additional 13% of the medial
quadrant restraining force. If the deficit produced by attenuation of
the medial vectors after acute dislocation is not eliminated,
patellofemoral balance is lost, resulting in feelings of giving way and
recurrent dislocation.

The patella is under significant biomechanical
compressive load during activity. It has been estimated that at 60
degrees of knee flexion, the forces across the patellofemoral
articulation are three times the body weight and increase to over seven
times the body weight during full knee flexion with weight-bearing.

The quadriceps mechanism is aligned in a slightly valgus
position in relation to the patellar tendon. This alignment can be
approximated by a line drawn from the anterosuperior iliac spine to the
center of the patella. The force of the patellar tendon is indicated by
a line drawn from the center of the patella to the tibial tubercle. The
angle formed by these two lines is called the quadriceps angle or Q angle (Fig. 24-20).
As this angle increases, the pull of the extensor mechanism tends to
sublux the patella laterally. Recurrent patellar dislocation is most
likely associated with some congenital or developmental deficiency of
the extensor mechanism, such as patellofemoral dysplasia, deficiency of
the vastus medialis obliquus, or an increased Q angle with valgus
malalignment of the quadriceps-patellar tendon complex.

Most acute patellar dislocations in children reduce spontaneously; if not, reduction usually can be easily obtained. After

appropriate sedation, reduction is done by flexing the hip to relax the
quadratus femoris, gradually extending the knee, and gently pushing the
patella medially back into its normal position. Gentle reduction should
be emphasized to avoid the risk of osteochondral fracture associated
with patellar relocation.

Surgery is usually not indicated for acute patellar dislocations in children.²⁹,⁶³,¹⁶⁹
Most patellar dislocations are treated nonoperatively with
immobilization, followed by patellofemoral bracing and rehabilitation.
Surgical repair may be indicated if the vastus medialis obliquus and/or
medial patellofemoral ligament is completely torn from the medial
aspect of the patella, leaving a large, palpable soft tissue gap. If
osteochondral fracture has occurred, arthroscopy/arthrotomy may be
indicated for removal or repair of an osteochondral loose body as
discussed in the previous section.

Recurrent instability of the patella which has been
recalcitrant to nonoperative treatment is typically managed through
various proximal/distal patellofemoral realignment procedures. Surgical
options include isolated or combination procedures including lateral
retinacular release, medial retinacular plication, extensor mechanism
realignment, Galeazzi semitendinosis tenodesis, patellar tendon
hemitransfer, and tibial tunbercle osteotomy. Tibial tubercle osteotomy
is contraindicated in patients with an open tibial tubercle apophysis
due to the risk of a growth arrest resulting in recurvatum deformity.
Recently, increased attention has been paid to medial patellofemoral
ligament reconstruction.³¹,⁵³,⁷⁴

The prognosis of patellar dislocations in children is
generally good. Approximately 1 in 6 children with acute patellar
dislocations experiences recurrent dislocations. Patients with a
younger age at first dislocation are at higher risk for recurrent
instability. Cash and Hughston⁵⁸ noted 75% satisfactory results after nonoperative treatment in carefully selected patients.

Recurrent patellar dislocations with associated osteochondral injuries may lead to osteoarthritis of the patellofemoral joint.

Complications may occur after surgery for patellar
instability. Lateral release alone without medial retinaculum/medial
patellofemoral ligament repair may not adequately prevent recurrent
dislocation. Stiffness, with lack of knee flexion, may occur after
Galeazzi tenodesis, if the graft is overly tensioned. After tibial
tubercle osteotomy, nonunion, hardware failure, neurovascular injury,
and compartment syndrome have been reported.

Meniscal injuries in the pediatric athlete are being seen with increased frequency.^†
Meniscal disorders include meniscal tears, discoid meniscus, and
meniscal cysts. The exact incidence of meniscal injuries in children
and adolescents is unknown. King¹⁶⁴
reported 52 patients younger than 15 years of age who had undergone
arthrotomy because of suspected meniscal injuries, and Fowler¹⁰²
reported 117 meniscectomies in patients 12 to 16 years of age. Meniscal
injuries under the age of 10 are rare, unless associated with a discoid
meniscus.^‡ The incidence of meniscal, as well as other intra-articular disorders, increases with age.⁷³
With adolescence, increased size and speed, and increased athletic
demands, come higher-energy injuries and an increase of intra-articular
lesions.

Meniscal injury patterns differ in children compared to
adults. It is estimated that longitudinal tears comprise 50% to 90% of
meniscal tears in children and adolescents.¹⁷⁶ Bucket-handle displaced tears are not uncommon (see Fig. 24-1). Also in these age groups, meniscal injuries are commonly associated with ACL injuries.⁵⁷,⁸⁸,¹⁷⁷,²⁰³ Cannon⁵⁷
estimated that repairable meniscal tears occur in 30% of all knees with
acute ACL rupture and in 30% of patients under 20 years old.
Approximately two thirds of repairable meniscal tears are associated
with ACL rupture, with the majority of these tears limited to the
posterior horn.

The incidence of medial meniscal tears is greater than
lateral meniscal tears in the pediatric and especially the adolescent
age group.²⁸¹ There appears to be a relatively increased incidence

of lateral tears in the preadolescent age group, which may be due to the existence of lateral discoid menisci.¹⁷⁶

The menisci become clearly defined by as early as 8 weeks of embryologic development.¹⁵⁷
By week 14, they assume the normal mature anatomic relationships. At no
point during their embryology are the menisci discoid in morphology.¹⁵⁷
Thus, the discoid meniscus represents an anatomic variant, not a
vestigial remnant. The developmental vasculature of the menisci has
been studied extensively by Clark.⁶²
The blood supply arises from the periphery and supplies the entire
meniscus. This vascular pattern persists through birth. During
postpartum development, the vasculature begins to recede and, by the
ninth month, the central third is avascular. This decrease in
vasculature continues until approximately age 10, when the menisci
attain their adult vascular patter. Injection dye studies by Arnoczky
and Warren²² have shown that only
the peripheral 10% to 30% of the medial and 10% to 25% of the lateral
meniscus receive vascular nourishment.

The medial meniscus is C-shaped. The posterior horn is
larger in anterior-posterior width than the anterior horn. The medial
meniscus covers approximately 50% of the medial tibial plateau. The
medial meniscus is attached firmly to the medial joint capsule through
the meniscotibial or coronary ligaments. There is a discrete capsular
thickening at its midportion which constitutes the deep MCL. The
inferior surface is flat and the superior surface concave so that the
meniscus conforms to its respective tibial and femoral articulations.
To maintain this conforming relationship, the medial meniscus
translates 2.5 mm posteriorly on the tibia as the femoral condyle rolls
backward during knee flexion.¹¹⁷,¹¹⁸

The lateral meniscus is more circular in shape and
covers a larger portion, approximately 70%, of the lateral tibial
plateau. The lateral meniscus is more loosely connected to the lateral
joint capsule. There are no attachments in the area of the popliteal
hiatus and the fibular collateral ligament does not attach to the
lateral meniscus. Accessory meniscofemoral ligaments exist in up to one
third of cases. These arise from the posterior meniscus. If this
ligament inserts anterior to the PCL, it is known as the ligament of
Humphrey; if it inserts posterior to the PCL, it is known as the
ligament of Wrisberg. Due to the lack of restraining forces, the
lateral meniscus is able to translate 9 to 11 mm on the tibia with knee
flexion. This may account for the lower incidence of lateral meniscal
tears. Both menisci are attached anteriorly via the anterior transverse
meniscal ligament.¹¹⁷,¹¹⁸

The blood supply arises from the superior and inferior,
medial and lateral geniculate arteries. These vessels form a
perimeniscal synovial plexus. There may be some contribution from the
middle geniculate artery. King,¹⁶⁵
in the 1930s, published classic research indicating that the peripheral
meniscus did communicate with the vascular supply and thus was capable
of healing. It is believed that the inner two thirds of the meniscus
receives its nutrition through diffusion and mechanical pumping.

The menisci are composed primarily of type I collagen (60% to 70% is dry weight). Lesser amounts of types II, III, and

VI collagen are also present. The collagen fibers are oriented
primarily in a circumferential pattern, parallel with the long access
of the meniscus.¹¹⁷,¹¹⁸
There are also radial, oblique, and vertically oriented fibers.
Proteoglycans and glycoproteins are present in smaller concentrations
than in articular cartilage. The menisci also contain neural elements
including mechanoreceptors and type I and II sensory fibers. In a
sensory mapping study, Dye⁸²
demonstrated that the probing of the peripheral meniscus led to pain
where as stimulation of the central meniscus elicited little or no
discomfort.

Our understanding of the functional importance of the meniscus has evolved. In 1897, Bland-Sutton⁴⁵
characterized the menisci as “functionless remnants of intra-articular
leg muscles.” The sentiment was held onto through the 1970s, when
menisci were routinely excised. Fairbanks,⁹³
in 1948, published the first long-term follow-up of patients after
total menisectomy. His article warned that degenerative changes
followed menisectomy in a substantial proportion of patients. Now,
several reports have established the deleterious consequences of total
and even partial meniscectomy.⁵,⁷¹,⁸⁸,¹⁷⁶,²⁰³,²¹⁴,²⁴⁶,²⁴⁸,²⁹⁵,³⁰³,³¹³
Nowhere are these facts more important than in children and
adolescents, in whom the long-term effects of menisectomy will be
magnified by the activity level and longevity.

It is now realized that the menisci have many functions.
The menisci serve to increase contact area and congruency of the
femoral tibial articulation. This allows the menisci to participate in
load sharing and reduces the contact stresses across the knee joint. It
is estimated that the menisci transmit up to 50% to 70% of the load in
extension and 85% of the load in 90 degrees of flexion.⁶ Baratz and Fu²⁸
showed that after total meniscectomy, contact area may decrease by 75%
and contact stresses increase by 235%. They also documented the
deleterious effects of partial menisectomy, demonstrating that the
contact stresses increased in proportion to the amount of meniscus
removed. Excision of small bucket-handle tears of the medial meniscus
increased contact stress by 65%, and resecting 75% of the posterior
horn increased contact stresses equivalent to that after total
meniscectomy.²⁸ Repair of meniscal
tears, by either arthroscopic or open techniques, reduced the contact
stresses to normal. Multiple other studies have corroborated the
mechanical importance of the meniscus.¹¹⁷,¹¹⁸

Meniscal tissue is about half as stiff as articular
cartilage, allowing it to participate in shock absorption. Shock
absorption capacity in the normal knee is 20% higher than in the
menisectomized knee.¹⁸⁹,³⁰⁰
The menisci also have a role in joint stability. In the ACL deficient
knee, the posterior horn of the medial meniscus plays a very important
passive stabilizing role. In the ACL deficient knee, medial menisectomy
leads to a 58% increase in anterior translation at 90 degrees of
flexion.¹⁸⁹,²⁶⁷
Given the presence of neural elements with in their substance, it is
also theorized that the menisci may have a role in proprioception.

Some small, nondisplaced meniscal tears in the outer
vascular region of the meniscus may heal nonoperatively or may become
asymptomatic.¹¹⁷,¹¹⁸,¹⁷⁶
Nonoperative treatment usually consists of rehabilitation of the
injured knee with the avoidance of pivoting and sports for 12 weeks.

However, the majority of meniscal tears in pediatric patients are larger and require surgical treatment.¹¹⁷,¹¹⁸,¹⁷⁶
Arthroscopic management is standard, with either partial menisectomy
using motorized shavers and baskets or meniscal repairs using
outside-in, all-inside, or inside-out techniques.¹⁵⁵,²²⁵,³⁰⁸

The traditional treatment of a torn meniscus has been menisectomy, but numerous reports⁵,²¹,⁴²,⁸⁸,¹³⁸,¹⁶⁴,¹⁷⁶,¹⁸³,²⁰³,²¹⁴,²⁴⁶,²⁴⁷,²⁹⁰,²⁹⁵,³⁰³,³¹³
indicating the poor long-term results of menisectomy in children have
made this less common. Up to 60% to 75% of patients have degenerative
changes after menisectomy. Manzione et al.²⁰³ reported 60% poor results in 20 children and adolescents after menisectomy. In cadaver studies, Baratz et al.²⁸
showed that the contact stresses on the tibiofemoral articulation
increase in proportion to the amount of the meniscus removed and the
degree of disruption of the meniscal structure. Clearly, as much of the
meniscus should be preserved as possible.

The exact meniscal injury and potential for repair can
be determined arthroscopically to help formulate treatment plans. Zaman
and Leonard³¹⁶ recommended
observation of small peripheral tears, repair of larger peripheral
tears, and, when necessary, partial menisectomy, leaving as much of the
meniscus as possible; they concluded that total menisectomy is
contraindicated in young patients. In general, peripheral tears, which
are most common in children, and longitudinal tears are good candidates
for repair, with success rates of up to 90% reported.⁷⁰,¹²⁷,¹³⁴,²²⁴

Although King¹⁵⁷
suggested over six decades ago that, based on experimental evidence in
dogs, longitudinal meniscal tears could heal if communication with
peripheral blood supply existed, it was not until the work of Arnoczky
and Warren²³ in the 1980s that
meniscal repairs were begun based on documentation of the meniscal
blood supply. They believed that tears within 3 mm of the
meniscosynovial junction were vascularized, and ones more than 5 mm
away were avascular unless bleeding was seen at surgery. Tears in the
3- to 5-mm range had inconsistent vascularity. Children and adolescents
may have greater healing potential for meniscal repair. In adults,
meniscal repair is indicated for tears involving the outer third. In
children and adolescents, repair of tears in the middle third zone
typically heal as well.⁷⁰,¹²⁷,¹³⁴,²²⁴

The prognosis after complete or near-total menisectomy is poor with numerous reports^* indicating poor long-term results with degenerative changes.

The prognosis of meniscus repair in appropriately selected cases is good. Mintzer and Richmond²²¹
reported on meniscal repair in 29 patients under the age of 18 (25 had
closed physes and 17 underwent concomitant ACL reconstruction). They
reported 100% clinical healing at an average follow up of 5 years.²²¹ Noyes and Barber-Westin²²⁹ looked at meniscal tears extending into the avascular zone in patients younger than 20 years old.⁹¹
Skeletal maturity had been reached in 88%. Their success rate in this
group was 75%. This study showed a higher rate of healing with
concomitant ACL reconstruction. Eggli et al.⁸⁸
found an overall healing rate for repair of isolated meniscal tears of
88% in patients younger than 30, compared to 67% in patients over age
30. Johnson et al.¹⁵⁰ showed a 76% healing rate at an average follow-up of greater than 10 years in a population

that averaged 20 years old at the time of surgery. Factors that have
been shown to correlate with increased healing of meniscal repairs
include younger age, decreased rim width (peripheral tears), repairs of
the lateral meniscus, concomitant ACL reconstruction, time from injury
to surgery of less than 8 weeks, and tear length of less than 2.5 cm.³,⁵⁶,⁵⁷,⁸⁸,¹¹⁷,¹¹⁸,¹⁵⁰,²⁹¹

Complications after either arthroscopic or open repair
may include hemorrhage, infection, persistent effusion, stiffness, and
neuropathy. Both the popliteal artery and inferior geniculate branches
are close to the posterior capsule and are easily lacerated.
Postoperative infection should be suspected if swelling or pain
persists with an elevated temperature. Swelling is best treated with
external compression dressings, and stiffness is best prevented by
appropriate postoperative rehabilitation. Neuroma formation rarely
causes significant symptoms, but occasionally persistent localized
tenderness may warrant excision.

Ligamentous injuries of the knee in children and adolescents were once considered rare.⁶⁵,²⁴⁷ Tibial eminence avulsion fractures were considered the pediatric ACL injury equivalent.¹⁷⁰,¹⁷⁵,¹⁷⁷,²⁴⁷ However, major ligamentous injuries are being seen with increased frequency and have received increased attention.^†
The increased frequency of diagnosis of knee ligament injuries in
children is likely related to increased participation in youth sports
at higher competitive levels, the advent of arthroscopy and MRI, and an
increased awareness of injuries in this age group.

ACL injury has been reported in 10% to 65% of pediatric
knees with acute traumatic hemarthroses in series ranging from 35 to
138 patients.⁹¹,¹⁶⁸,¹⁷⁹,¹⁹⁷,²⁸¹,²⁹³ Stanitski et al.²⁷⁸
reported 70 children and adolescents with acute traumatic knee
hemarthroses; arthroscopic examination revealed ACL injuries in 47% of
those 7 to 12 years of age and in 65% of those 13 to 18 years of age.
They determined that boys 16 to 18 years of age engaged in organized
sports and girls 13 to 15 years of age engaged in unorganized sports
had the highest risk for complete ACL tears; 60% of these patients had
isolated ACL tears.

Injury patterns in the skeletally immature knee are
dependent on the loading conditions and the developmental anatomy.
Fractures of the epiphyses or physes about the knee are more common
than ligamentous injuries alone. Isolated knee ligament injury in
children younger than 14 years of age tends to be rare because of the
relative strength of the ligaments compared to the physes.⁸³,¹⁵³,²⁰⁸,³⁰²
The inherent ligamentous laxity in children also may offer some
protection against ligament injury, but this decreases as the
adolescent approaches skeletal maturity. Faster loading conditions
favor ligamentous injuries, whereas slower loading conditions favor
fracture. Narrowing of the intercondylar notch during skeletal
development may also predispose to ligamentous injury.¹⁷⁵ Fractures and ligamentous injuries may occur concurrently. Bertin and Goble,³⁹
after reviewing 29 fractures, concluded that physeal fractures about
the knee are associated with a higher incidence of ligamentous injury
than physeal fractures around other joints. In addition, tibial
eminence fractures, even after anatomic fixation and healing, tend to
demonstrate persistent ACL laxity.¹⁷⁰

Before the 1990s, reports of ligamentous injuries in
children were isolated case reports, and most recommendations were for
conservative treatment. More recent reports have indicated an increased
awareness of ligament injury in association with physeal fractures,⁶⁵ as well as isolated ligament injuries, and a more aggressive approach, especially in adolescents approaching skeletal maturity.³⁷,⁸⁹,⁹⁰,²²⁴,²⁶⁸,²⁸⁷
Management of some of these injuries, particularly ACL injuries in
skeletally immature patients, is controversial. Nonreconstructive
treatment of complete tears typically results in recurrent functional
instability with risk of injury to meniscal and articular cartilage. A
variety of reconstructive techniques have been utilized, including
physeal sparing, partial transphyseal, and transphyseal methods using
various grafts. Conventional adult ACL reconstruction techniques risk
potential iatrogenic growth disturbance due to physeal violation.
Growth disturbances after ACL reconstruction in skeletally immature
patients have been reported.

The MCL and LCL of the knee originate from the distal
femoral epiphysis and insert into the proximal tibial and fibular
epiphyses, except for the superficial portion of the MCL, which inserts
into the proximal tibial metaphysis distal to the physis (Fig. 24-35).
In children, these ligaments are stronger than the physes, and
significant tensile stresses usually produce epiphyseal or physeal
fractures rather than ligamentous injury. The ACL originates from the
posterolateral intercondylar notch and

inserts
into the tibia slightly anterior to the intercondylar eminence. The PCL
originates from the posteromedial aspect of the intercondylar notch and
attaches on the posterior aspect of the proximal tibial epiphysis. The
ACL in children has collagen fibers continuous with the perichondrium
of the tibial epiphyseal cartilage; in adults, the ligament inserts
directly into the proximal tibia by way of Sharpey’s fibers. This
anatomic difference probably accounts for the fact that fracture of the
anterior tibial spine occurs more frequently in children than does ACL
injury.

Isolated collateral ligament injuries are usually successfully treated with bracing and rehabilitation.

Controversy exists regarding the management of ACL
injuries in patients with open physes. Nonoperative management of
partial tears may be successful in some patients.¹⁷⁹
However, nonoperative management of complete tears in skeletally
immature patients generally has a poor prognosis with recurrent
instability leading to further meniscal and chondral injury, which has
implications in terms of development of degenerative joint disease.¹¹,¹¹⁵,¹⁴⁷,²⁰⁹,²²⁰,²²²,²⁴⁴ Graf et al.,¹¹⁵ Mizuta et al.,²²² and Janarv et al.¹⁴⁷
have reported instability symptoms, subsequent meniscal tears,
decreased activity level, and need for ACL reconstruction in the
majority of skeletally immature patients treated nonoperatively in
series of 8, 18, and 23 patients, respectively. Similarly, when
comparing the results of operative versus nonoperative management of
complete ACL injuries in adolescents, McCarroll et al.²⁰⁹ and Pressman et al.²⁴⁴
found that those managed by ACL reconstruction had less instability,
higher activity and return to sport levels, and lower rates of
subsequent reinjury and meniscal tears.

Conventional surgical reconstruction techniques risk
potential iatrogenic growth disturbance due to physeal violation. Cases
of growth disturbance have been reported in animal models⁸⁶,¹²¹,¹³⁶ and clinical series.¹⁸⁰,¹⁸²,¹⁹²
Animal models have demonstrated mixed results regarding growth
disturbances from soft tissue grafts across the physes. In a canine
model with iliotibial band grafts through 5/32 inch tunnels,
Stadelmeier et al.²⁷⁷ found no
evidence of growth arrest in the four animals with soft tissue graft
across the physis, whereas the four animals with drill holes and no
graft demonstrated physeal arrest. In a sheep model of transphyseal
reconstruction, Seil et al.²⁶² did
not find clinically relevant growth disturbances despite consistent
physeal damage. In a rabbit model using a semitendinosis graft through
2-mm tunnels, Guzzanti et al.¹²¹ did
have cases of growth disturbance; however, these were not common: 5%
shortening (1/21) and 10% distal femoral valgus deformity (2/21).
Examining the effect of a tensioned soft tissue graft across the
physis, Edwards et al.⁸⁶ found a
substantial rate of deformity. In a canine model with iliotibial band
graft tensioned to 80 N, these investigators found significant
increases, compared to the nonoperated control limb, in distal femoral
valgus deformity and proximal tibial varus deformity despite no
evidence of a bony bar.⁸⁶ Similarly, Houle et al.¹³⁶ reported growth disturbance after a tensioned tendon graft in a bone tunnel across the rabbit physis.

Clinical reports of growth deformity after ACL reconstruction are unusual. Lipscomb and Anderson¹⁹²
reported one case of 20 mm shortening in a series of 24 skeletally
immature patients reconstructed with transphyseal semitendinosis and
gracilis grafts. This was associated with staple graft fixation across
the physis. Koman and Sanders¹⁸²
reported a case of distal femoral valgus deformity requiring osteotomy
and contralateral epiphyseodesis after transphyseal reconstruction with
a doubled semitendinosis graft. This case was also associated with
fixation across the distal femoral physis. Kocher et al.¹⁸⁰
reported an additional 15 cases of growth disturbances gleaned from a
questionnaire of expert experience, including 8 cases of distal femoral
valgus deformity with an arrest of the lateral distal femoral physis, 3
cases of tibial recurvatum with an arrest of the tibial tubercle
apophysis, 2 cases of genu valgum without arrest due to a lateral
extra-articular tether, and 2 cases of leg-length discrepancy (one
shortening and one overgrowth). Associated factors included fixation
hardware across the lateral distal femoral physis in three cases, bone
plugs of a patellar tendon graft across the distal femoral physis in
three cases, large (12-mm) tunnels in two cases, lateral
extra-articular tenodesis in two cases, fixation hardware across the
tibial tubercle apophysis in two cases, over-the-top femoral position
in one case, and suturing near the tibial tubercle apophysis in one
case.¹⁸⁰

Surgical techniques to address ACL insufficiency in
skeletally immature patients include primary repair, extra-articular
tenodesis, transphyseal reconstruction, partial transphyseal
reconstruction, and physeal sparing reconstruction. Primary ligament
repair⁶¹,⁹² and extra-articular tenodesis alone¹¹⁵,²⁰⁹
have had poor results in children and adolescents, similar to adults.
Transphyseal reconstructions with tunnels that violate both the distal
femoral and proximal tibial physes have been performed with hamstrings
autograft, patellar tendon autograft, and allograft tissue.¹¹,¹⁸¹,¹⁹¹,²⁰⁹
Partial transphyseal reconstructions violate only one physis with a
tunnel through the proximal tibial physis and over-the-top positioning
on the femur or a tunnel through the distal femoral physis with an
epiphyseal tunnel in the tibia.¹⁷,⁴⁴,¹²³
A variety of physeal-sparing reconstructions have been described to
avoid tunnels across either the distal femoral or proximal tibial
physis.¹⁴,⁵²,⁷⁷,¹²²,¹³⁸,¹⁶²,¹⁷¹,¹⁷²,²¹⁸,²⁹³

In prepubescent patients, physeal sparing techniques
have been described that utilize hamstrings tendons under the
intermeniscal ligament and over-the-top on the femur, through
allepiphyseal femoral and tibial tunnels, and with a femoral epiphyseal
staple.¹⁴,⁵²,⁷⁷,¹²²,¹⁶²,²¹⁸,²³⁸,²⁹³
In adolescent patients with growth remaining, transphyseal
reconstructions have been performed with hamstrings autograft, patellar
tendon autograft, quadriceps tendon autograft, and allograft tissue.¹¹,²⁰,²⁴,⁸⁵,¹⁰⁴,¹⁰⁹,¹¹⁰,²⁰⁵,²⁰⁹,²¹⁰,²⁶⁶,²⁷⁰,²⁷⁸,³⁰¹
In addition, partial transphyseal reconstructions have been described
with a tunnel through the proximal tibial physis and over-the-top
positioning on the femur or a tunnel through the distal femoral physis
with an epiphyseal tunnel in the tibia.¹⁷,⁴⁴,¹²³,¹⁹³

The prognosis of nonoperative management of complete
tears in skeletally immature patients is generally poor with recurrent
instability leading to further meniscal and chondral injury which has
implications in terms of development of degenerative joint disease.¹¹,¹¹⁵,¹²¹,¹⁴⁷,²⁰⁹,²²⁰,²²²,²⁴⁴

The prognosis of ACL reconstruction depends on the
surgical procedure. Several case series exist regarding ACL
reconstruction in skeletally immature patients. However, most series
are small and variably report the patients’ skeletal age and growth
remaining. Primary ligament repair⁶¹,⁹² and extra-articular tenodesis alone¹¹⁵⁸,²⁰⁹
have had poor results in children and adolescents, similar to adults.
Transphyseal reconstructions with tunnels that violate both the distal
femoral and proximal tibial physes have been performed with hamstrings
autograft, patellar tendon autograft, and allograft tissue.¹¹,²⁰,²⁴,⁸⁵,¹⁰⁴,²⁰⁵,²⁰⁹,²¹⁰,²⁶⁶,²⁷⁰,²⁷⁸,³⁰¹
These anatomic ACL reconstruction procedures have high success rates as
in adult patients; however, there is risk injury to the physis,
particularly in prepubescent patients. In a follow-up outcome study of
61 knees in 59 skeletally immature Tanner stage 3 adolescents with
growth remaining (mean chronologic age: 14.7 years old, range: 11.6 to
16.9 years old) who underwent transphyseal reconstruction with
autogenous hamstrings graft and metaphyseal fixation, a revision rate
of 3% with excellent functional outcome, return to competitive sports,
and no cases of growth disturbance was found.¹⁸¹
Partial transphyseal reconstructions violate only one physis with a
tunnel through the proximal tibial physis and over-the-top positioning
on the femur or a tunnel through the distal femoral physis with an
epiphyseal tunnel in the tibia.¹⁷,⁴⁴,¹²³ These procedures are also near anatomic with good clinical results; however, the potential for growth disturbance exists.

A variety of physeal-sparing reconstructions have been
described to avoid tunnels across either the distal femoral or proximal
tibial physis.¹⁴,⁵²,⁷⁷,¹²²,¹⁶²,²¹⁸,²³⁸,²⁹³
In general, these procedures are nonanatomic and have some persistent
knee laxity; however, they avoid physeal violation. In a follow-up
outcome study of 44 skeletally immature prepubescent children who were
Tanner stage 1 or 2 (mean chronologic age: 10.3 years old; range:
3.6-14 years old) who underwent the physeal sparing combined
intra-articular and extra-articular ACL reconstruction technique using
autogenous iliotibial band that were described above, a revision ACL
reconstruction rate of 4.5% with excellent functional outcome, return
to competitive sports,

and no cases of growth disturbance was found.¹⁷¹,¹⁷² Anderson¹⁴,¹⁵
described a more anatomic physeal-sparing reconstruction in
prepubescent children by utilizing carefully placed epiphyseal femoral
and tibial tunnels with an autogenous hamstrings graft and epiphyseal
fixation (Fig. 24-42). In 12 skeletally
immature patients with mean age 13.3 years old (SD: 1.4), he found
excellent functional outcome without growth disturbance.¹⁴,¹⁵

Complications after ligament injury in children are
similar to adults: arthrofibrosis, persistent instability, unrecognized
concomitant injury, infection, graft failure, neurovascular injury, and
donor site morbidity. In skeletally immature patients, growth
disturbance can occur from iatrogenic physeal injury as previously
discussed.