Monteggia Fracture-Dislocation in Children

A type I lesion is an anterior dislocation of the radial
head associated with an ulnar diaphyseal fracture at any level. This is
the most common Monteggia lesion in children.³⁴,⁴⁹,⁷⁵,¹¹¹

A type II lesion is a posterior dislocation of the
radial head associated with an ulnar diaphyseal or metaphyseal
fracture. This is the most common lesion in adults but very rare in
children.⁹⁷,⁹⁸,¹¹¹

A type III lesion is a lateral dislocation of the radial
head associated with an ulnar metaphyseal fracture. This is the second
most common pediatric Monteggia lesion.¹³,⁴⁴,⁹¹,⁹⁵,¹⁴³
When associated with an olecranon fracture and a lateral or
anterolateral radiocapitellar dislocation but no radioulnar
dissociation, the injury is not a true Monteggia lesion.⁶⁰,¹¹⁰,¹³⁴

A type IV lesion is an anterior dislocation of the radial head associated with fractures of both
the ulna and the radius. The original description was of a radial
fracture at the same level or distal to the ulna fracture. This, too,
is a relatively rare injury.

Type I equivalents include isolated anterior
dislocations of the radial head without ulnar fracture. This
subclassification includes a “pulled elbow” or “nursemaid’s elbow”
because the mechanism of longitudinal traction, pronation, and
hyperextension is similar to a true type I Monteggia lesion. In this
situation, the radiographs are normal. In addition, an isolated
anterior dislocation of the radial head without ulnar fracture is a
type I equivalent. The ulnar bow sign (Fig. 12-3)
is normal. Subtle plastic deformation of the ulna will have a concave
ulnar bow and could be misdiagnosed as an equivalent lesion when it is
really a true type I lesion. This distinction can be critical in terms
of operative decisions in that the rare but true type I equivalent
lesion requires only open repair of the displaced ligament while the
type I lesion with plastic deformation requires correction of the ulnar
deformity. Other type I equivalencies described thus far include:
anterior dislocation of the radial head with ulnar diaphyseal and
radial neck fractures, anterior dislocation of the radial head with
radial diaphyseal fracture more proximal to ulnar diaphyseal fracture,
anterior radial head dislocation with ulnotrochlear dislocation (Fig. 12-4),¹¹¹ and anterior dislocation of the radial head with segmental ulna fracture.^2.49,⁶⁰,¹⁰²,¹¹⁵,¹³⁴
More case reports will probably expand this subclassification. The type
I equivalent lesions have been shown to have poorer outcomes and
require more operative interventions than other Monteggia lesions.⁴⁹,⁹¹

Bado⁸,⁹ described type II equivalents to include fractures of the proximal radial epiphysis or radial neck.

Bado⁸,⁹ did not have equivalent lesions for his type III and type IV true Monteggia lesions. Since mechanism of injury allows

for subclassification, case reports have emerged over time to include
fractures of the distal humerus (supracondylar, lateral condylar) in
association with proximal forearm fractures (Fig. 12-5).^*

The annular ligament is one of the prime stabilizers of
the proximal radioulnar joint during forearm rotation. It surrounds the
radial neck from its origin and insertion on the proximal ulna (Fig. 12-7).
Due to the shape of the radial head, it tightens in supination. It is
part of the lateral collateral ligamentous complex that stabilizes the
distal humerus and proximal forearm. Displacement of the annular
ligament occurs in a Monteggia lesion.

The quadrate ligament³¹,⁶⁴ is just distal to the annular ligament and connects the proximal radius and ulna (Fig. 12-8). It has a dense anterior portion, thinner posterior portion, and even

thinner central portion. The quadrate ligament also provides stability
to the proximal radioulnar joint during forearm rotation. The anterior
and posterior borders become taut at the extremes of supination and
pronation respectively.

The oblique ligament extends from the ulna proximally to the radius distally (see Fig. 12-8).
The origin of the oblique ligament is just distal to the radial notch
of the ulna, and its insertion is just distal to the bicipital
tuberosity of the radius. With supination, the oblique ligament
tightens and provides further stability to the proximal radioulnar
joint.

The interosseous ligament is distal to the oblique
ligament with its fibers running in the opposite direction (from radius
proximally to ulna distally) to the oblique ligament (see Fig. 12-8).
However, similar to the oblique ligament, it tightens in supination and
provides further stability to the proximal radioulnar joint.

The shape of the radial head is elliptical in cross section (Fig. 12-9).
In supination, the long axis of the ellipse is perpendicular to the
proximal ulna, causing the annular ligament and the anterior portion of
the quadrate ligament to tighten and stabilize the proximal radioulnar
joint. In addition, the contact area between the radius and the radial
notch of the ulna increases in supination due to the broadened surface
of the elliptical radial head proximal to distal in that position. This
may provide some additional stability.

The radius “radiates” around the ulna. It must have an
anatomic bow in order to achieve full forearm rotation while
maintaining stability in the proximal and distal radioulnar joints (see
Fig. 12-9). With the radius in supination, the
bow tightens the oblique and interosseous ligaments, thereby increasing
proximal radioulnar joint stability.

The biceps inserts into the bicipital tuberosity of the
radius and acts as both a flexor of the elbow and supinator of the
forearm. It is a deforming force in anterior Monteggia
fracture-dislocations, pulling the radius anteriorly as the elbow is
forcibly extended. In treatment, care is taken to maintain the elbow in
flexion to prevent recurrent anterior subluxation of the radial head
while the soft tissues heal.

The anconeus may act as a dynamic stabilizer of the
elbow joint by providing a valgus moment at the joint during extension
and pronation.¹¹,¹³⁹
It may also act as a deforming force, along with the forearm flexors,
on complete fractures of the ulna in a Monteggia lesion. Surgical
exposure of the proximal radioulnar and radiocapitellar joints is
usually through the anconeus-extensor carpi ulnaris interval.

The radial nerve passes the distal humerus in the brachialis-brachioradialis interval (Fig. 12-10).
As it descends into the forearm, it divides into the radial sensory
nerve and the posterior interosseous motor branch. The posterior
interosseous nerve passes between the two heads of the supinator, when
present, or beneath the supinator when there is only one head of
supinator. Its close proximity to the proximal radial head and neck
makes it susceptible to injury with Monteggia lesions.⁶⁷
In chronic Monteggia situations, the posterior interosseous nerve can
become adherent to the dislocated head or, less commonly, entrapped in
the joint.¹¹³ Care must be taken with the nerve in surgical reconstructions of the chronic anterior dislocation.

The ulnar nerve passes posterior to the medial
intermuscular septum of the humerus, through the cubital tunnel behind
the medial epicondyle, and then through the flexor carpi ulnaris into
the forearm. It is at risk for injury with type II laterally displaced
Monteggia lesions and with ulnar lengthening in chronic Monteggia
reconstructions.

Bado,⁸,⁹ in his original description, provided an accurate clinical picture of Monteggia fracture-dislocations. In general, there is

fusiform swelling about the elbow. The child has significant pain and
has limitations of elbow motion in flexion and extension as well as
pronation and supination. Usually, an angular change in the forearm
itself is evident, with the apex shifted anteriorly and mild valgus
apparent. There may be tenting of the skin or an area of ecchymosis on
the volar aspect of the forearm. It is imperative to check for an open
fracture wound. The child may not be able to extend the digits at the
metacarpophalangeal joint or at the interphalangeal joint of the thumb
because of a paresis of the posterior interosseous nerve. Later, as the
swelling subsides, anterior fullness may remain in the cubital fossa
for the typical Bado type I anterior dislocation. However, this may be
subtle since children will usually have an elbow flexion posture
postinjury. If the injury is seen late, there will be a loss of full
flexion at the elbow and a palpable anterior dislocation of the radial
head. The radial head-distal humerus impingement that occurs may be a
source of pain with activities. There is usually loss of forearm
rotation with late presentation. Progressive valgus may occur if the
anterior radial head dislocation worsens. Lateral dislocations will
generally have a varus bow to the forearm both with acute and chronic
presentations. The laterally displaced radial head will be visible and
palpable.

The standard evaluation of a type I Monteggia fracture
includes anteroposterior (AP) and lateral radiographs of the forearm.
Any disruption of the ulna, including subtle changes in ulnar bowing,
should alert the clinician to look for joint disruption at either end
of the forearm.²⁷,²⁸,⁶⁵,⁶⁷,⁷⁷ Unfortunately, the dislocated radial head is all too often missed in the acute setting.

The radiographic alignment of the radial head and
capitellum is particularly important and is best defined by a true
lateral view of the elbow. In a type I Monteggia fracture-dislocation,
the radiocapitellar relationship may appear normal on an AP radiograph
despite obvious disruption on the lateral view (Fig. 12-11). If there is doubt regarding the radiocapitellar alignment, further radiographic evaluation must be obtained. Smith¹¹⁸ and later Storen¹²⁸
noted that a line drawn through the center of the radial neck and head
should extend directly through the center of the capitellum. This
alignment should remain intact regardless of the degree of flexion or
extension of the elbow (Fig. 12-12). In some instances, there is disruption of the radiocapitellar line in a normal elbow. Miles and Finlay⁸⁴
pointed out that the radiocapitellar line passes through the center of
the capitellum only on a true lateral projection. They reported five
patients in whom the elbow was clinically normal but the
radiocapitellar line appeared disrupted. In analyzing the radiographs,
they found that the radiographic projection of the elbow was usually an
oblique view or that the forearm was pronated in the radiograph. If
this disruption appears on radiographs in a child with an acute injury,
however, it is the treating surgeon’s responsibility to ensure that it
is an insignificant finding. As Dr. John Hall⁵⁵
often said, “Monteggia lesions are not like throwing horse shoes; being
close does not count.” It is still too frequent an occurrence that a
highly qualified, distraught, orthopaedic surgeon will call for
referral of a chronic Monteggia lesion that was missed acutely.

With late presentation of a chronic Monteggia injury, a
magnetic resonance imaging (MRI) scan may be useful to determine the
congruency of the radial head and capitellum. If the radial head is no
longer centrally concave or the capitellum is no

longer symmetrically convex, surgical reduction may fail or produce pain and limited motion.

Traumatic versus Congenital Dislocation. When the
radiocapitellar relation is disrupted radiographically, evaluation of
the shape of the radial head and neck helps determine the cause of the
disruption, especially if there is no history of trauma or the
significance of the trauma is questioned. Bucknill²³ suggested that McFarland’s⁸¹
classic description of congenital radial head dislocation with an
atypical deformed radial head, dysplastic capitellum, concavity of the
posterior border of the proximal ulna, and periarticular ossifications
probably represented old traumatic dislocations. Lloyd-Roberts and
Bucknill⁷⁸ noted that many
unilateral anterior dislocations were most likely old traumatic
dislocations rather than congenital dislocations. Caravias²⁴
recognized that the existence of a congenital anterior dislocation as a
separate entity was doubtful and that true anterior congenital
dislocation of the radial head was rare. True congenital dislocations
are usually posterior, may be bilateral, and can be associated with
various syndromes such as Ehlers-Danlos, nail-patella, and Silver
syndromes (Fig. 12-13).³,⁷⁸
Therefore, all isolated anterior and anterolateral dislocations of the
radial head, regardless of symptoms, should be suspected as having a
traumatic origin unless there is evidence of congenital or systemic
differences, such as proximal radioulnar synostosis.

Three separate mechanisms of type I lesions have been described: direct trauma,⁹,²²,²⁵,³⁸,⁸⁹,¹⁰⁵,¹⁰⁸,¹²¹,¹³⁹ hyperpronation, and hyperextension.²²,¹⁰⁸

Direct Blow Theory. The first theory proposed in English literature was the direct blow mechanism described by Speed and Boyd¹²¹ and endorsed by Smith (Fig. 12-14).¹¹⁸ This theory was actually proposed by Monteggia,⁸⁵
who noted that the fracture occurs when a direct blow on the posterior
aspect of the forearm first produces a fracture through the ulna. Then,
either by continued deformation or direct pressure, the radial head is
forced anteriorly with respect to the capitellum, causing the radial
head to dislocate. Monteggia⁹⁹ explained that these injuries sometimes resulted from a blow by a staff or cudgel on the forearm raised to protect the head.

The parry fracture, another eponym for the Monteggia
fracture-dislocation, has been mentioned in the literature. During the
American Civil War, Monteggia fractures were frequent because of direct
blows on the forearm received while attempting to parry the butt of a
rifle during hand-to-hand combat. The major argument against this
theory as the mechanism is that in the usual clinical situation there
rarely is evidence of a direct blow to the posterior aspect of the
forearm, such as a contusion or laceration.³⁸,¹³⁹

Hyperpronation Theory. In 1949, Evans³⁸
published his observations regarding anterior Monteggia fractures.
Previous investigators had based their direct blow theory on hypothesis
and clinical observation, but Evans³⁸
used cadaver experiments to support his hypothesis. He demonstrated
that hyperpronation of the forearm produced a fracture of the ulna with
a subsequent dislocation of the radial head. He postulated that during
a fall, the outstretched hand, initially in pronation, is forced into
further pronation as the body twists above the planted hand and forearm
(Fig. 12-15). This hyperpronation causes the
radius to be crossed over the midulna, resulting in anterior
dislocation of the radial head or fracture of the proximal third of the
radius along with fracture of the ulna. In the patients reported in
Evans’³⁸ article, the ulnar
fractures demonstrated a pattern consistent with anterior tension and
shear or longitudinal compression. His cadaver studies, however, showed
the ulna fracture pattern to be consistent with a spiral or torsional
force. This theory was also supported by Bado.¹⁰

Two arguments have been used to dispute the hyperpronation mechanism.¹³⁹
First, the ulnar fracture rarely presents clinically in a spiral
pattern; it is often oblique, indicating an initial force in tension
with propagation in shear rather than rotation. Second, Evans’³⁸
experiments, which were done on totally dissected forearms, did not
take into consideration the dynamic muscle forces at play during a fall
on an outstretched hand.

Hyperextension Theory. In 1971, Tompkins¹³⁹
analyzed both theories and presented good clinical evidence that type I
Monteggia fractures were caused by a combination of dynamic and static
forces. His study postulated three steps in the fracture mechanism:
hyperextension, radial head dislocation, and ulnar fracture (Fig. 12-16).
The patient falls on an outstretched arm with forward momentum, forcing
the elbow joint into hyperextension. The radius is first dislocated
anteriorly by the violent reflexive contracture of the biceps, forcing
the radius away from the capitellum. Once the proximal radius
dislocates, the weight of the body is transferred to the ulna. Because
the radius is usually the main load-bearing bone in the forearm, the
ulna cannot handle the transmitted longitudinal force and weight and,
subsequently, fails in tension. This tension force produces an oblique
fracture line or a greenstick fracture in the ulnar diaphysis or
diaphyseal-metaphyseal junction. In addition to the momentum of the
injury, the anterior angulation of the ulna results from the pull of
the intact interosseous membrane on the distal fragment, causing it to
follow the radius. The brachialis muscle causes the proximal ulnar
fragment to flex at the elbow.

The Monteggia lesion can probably be caused by any of
the three proposed mechanisms, but the most common mechanism is a fall
on an outstretched hand that forces the elbow into complete extension,
locking the olecranon into the humerus. The forearm is in a rotational
position of neutral to midpronation. As the proximal ulna locks into
the distal humerus, the bending force stresses the proximal radioulnar
joint. Because of the relatively pronated position of the joint, the
ligamentous restraints are lax, providing only tenuous stability for
the radial head. The anterior bending force, combined with a reflexive
contraction of the biceps, violently dislocates the radial head
anteriorly. The radioulnar joint and its ligamentous complex are at
risk because of the ligamentous laxity and the decreased contact area
between the proximal radius and ulna created by the rotation of the
forearm. At midrotation, the short axis of the elliptical radial head
is perpendicular to the ulna, causing the annular ligament and the
dense anterior portion of the quadrate ligament to be relaxed. The
contact area of the proximal radioulnar joint, because of the shape of
the radial head, is also decreased, further reducing the stability of
the joint. The ulna, now the main weight-bearing structure of the
forearm, is loaded by a continued bending moment, causing tension on
the anterior cortex and producing failure. The force at the site of
failure is propagated in shear at approximately 45 degrees to the long

axis
of the ulna. This mechanism may produce plastic deformation with an
anterior bow, a greenstick fracture, or an oblique fracture pattern,
all of which are seen clinically. As the anterior bending movement
continues, the vector of the biceps changes and acts as a tether and
resists any further advance of the proximal radius. The distal fragment
of the ulna continues to advance, acting as a fulcrum against the
radial shaft. The anteriorly directed force of the distal ulnar
fragment, combined with the retrograde resistance of the biceps, may
create a fracture of the radius, or a type IV Monteggia lesion.

Although most treatment recommendations are based on the Bado classification, Ring and Waters¹¹¹
based their treatment choices on the type of ulnar fracture rather than
on the Bado type. Plastic deformation of the ulna is treated with
closed reduction of the ulnar bow to obtain stable reduction of the
radioulnar joint. Incomplete (greenstick or buckle) fractures of the
ulna are similarly treated with closed reduction and casting. Most
Monteggia injuries that are plastic deformation or greenstick fractures
in children are stable when immobilized in 100

to 110 degrees of flexion and full supination. In all series,⁴,⁹,²¹,²²,³⁴,⁴⁴,⁷⁵,⁹¹,¹⁰⁸,¹¹³,¹¹⁸,¹⁴³
anterior Monteggia lesions in children have uniformly good results when
treated by manipulative closed reduction, if the radial head is
properly aligned and the ulna fracture is reduced with length
preserved. These results most clearly apply to plastic deformation and
incomplete fractures, which make up the majority of anterior Monteggia
lesions. However, complete fractures can be unstable after closed
reduction. Therefore, with complete short oblique and transverse ulna
fractures or ones associated with a radial fracture (type IV),
intramedullary Kirschner wire (K-wire) fixation is recommended. At
times, this may involve use of the intramedullary K-wire in the
proximal fragment to joystick the reduction under fluoroscopic
guidance. Long oblique or comminuted fractures, which may develop
shortening and malalignment even with intramedullary fixation, are best
stabilized with plate and screw fixation. Using this treatment
protocol, Ring and Waters¹¹¹ reported excellent results in all 28 patients treated within 24 hours of injury (Table 12-2). Poor results occurred in two patients who were referred late with persistent radial head dislocations.

Closed Reduction and Cast Immobilization.

Reduction of the Ulnar Fracture.
The first step is to re-establish the length of the ulna by
longitudinal traction and manual correction of any angular deformity.
The forearm is held in relaxed supination as longitudinal traction is
applied with manual pressure directed over the apex of the deformity
until the malangulation is corrected clinically and radiographically (Fig. 12-18).
With plastic deformation fractures, this may necessitate significant
force that requires general anesthesia. With greenstick fractures, the
correction of the ulnar deformity and radial head reduction can often
be achieved with conscious sedation in the emergency room.

Some papers have cited successful treatment of acute
Monteggia lesions (defined as maintenance of the radial head reduction)
with nonanatomic alignment of the ulnar fracture (Fig. 12-19).⁴⁴,¹⁰³,¹⁰⁵ However, anatomic reduction and healing of the ulna fracture is strongly advocated.

Reduction of the Radial Head.
Once ulnar length and alignment have been reestablished, the radial
head can be relocated. This is often accomplished by simply flexing the
elbow to 90 degrees or more, thus producing spontaneous reduction (see Fig. 12-19).
Occasionally, posteriorly directed pressure over the anterior aspect of
the radial head is necessary for reduction of the radial head. Flexion
of the elbow to 110 to 120 degrees stabilizes the reduction. Once the
radial head position is established, it should be scrutinized
radiographically in numerous views to ensure a concentric reduction.
With a type I fracture, the optimal radiographic view is a true lateral
of the elbow with the forearm held in supination. The longitudinal axis
of the radius should pass directly through the center of the capitellum
(Fig. 12-20).

Alleviation of Deforming Forces.
Once the concentric reduction of the radial head is confirmed, the
elbow should be placed at approximately 110 to 120 degrees of flexion
to alleviate the force of the biceps, which could redislocate the
radial head (see Figs. 12-20 and 12-21).
The forearm is placed in a position of midsupination to neutral
rotation to alleviate the forces of the supinator muscle and the
anconeus, as well as the forearm flexors, which tend to produce radial
angulation of the ulna.

Immobilization. Once the
fracture is reduced and the neutralization position is established, a
molded long-arm splint or cast is applied to hold the elbow joint in
the appropriate amount of flexion, usually 110 to 120 degrees. Once the
cast is completed, careful radiographic assessment should establish the
concentric reduction of the radial head with respect to the capitellum,
as well as satisfactory alignment of the ulna.

Postreduction Care. The
patient is followed at 7 to 10 day intervals to confirm continued
satisfactory reduction by radiography. At 4 to 6 weeks after the
initial reduction, if there is radiographic evidence of consolidation
of the ulnar fracture and stability of the radial head, the long-arm
cast can be removed, with progressive guarded return to full activity.

Operative Treatment.

Indications. There are two
indications for operative treatment of type I fracture-dislocations:
failure to obtain and maintain ulnar fracture reduction and failure of
radial head reduction. The fractures most at risk are complete ulnar
fractures. On rare occasions, there will be an entrapped annular
ligament that prevents anatomic radial head reduction.

Failure of Ulnar Reduction.
If the ulnar fracture cannot be reduced or held in satisfactory
alignment by closed treatment, operative intervention is indicated. The
quality of the ulnar reduction affects the ability to reduce the radial
head, which is of primary importance. If the ulnar fracture can be
reduced but not maintained because of the obliquity of the fracture,
internal fixation is indicated.⁴⁴,⁹¹ Intramedullary fixation is standard in most series of Monteggia fracture-dislocations in children (Fig. 12-22).⁸,⁹,³⁴,⁴³,⁴⁴,⁷²,⁷⁴,⁷⁹,⁹¹,¹⁰⁴,¹¹¹,¹¹⁴,¹²⁸,¹⁴³
This method of fixation can be accomplished percutaneously, using image
intensification and flexible nails or K-wires. Entry can be through the
apophysis or proximal metaphysis of the ulna, depending on the level of
the fracture and surgeon’s preference. Intramedullary fixation is
preferred for transverse and short oblique fractures. Long oblique and
comminuted fractures may redisplace even with intramedullary fixation.
Plate and screw fixation is preferred with these rarer fractures.⁷⁴,⁹⁶,¹⁰¹,¹³⁶,¹⁴⁰,¹⁴⁵

Failure of Radial Head Reduction.
The second indication is failure to reduce the radial head
satisfactorily by closed means. This is more common in type III
Monteggia lesions, but it can also occur in type I lesions. It results
from soft tissue interposition, including entrapped capsule or an
orbicular ligament pulled over the radial head.¹³⁹,¹⁴⁵ Interposed cartilaginous or

osteochondral fractures (Fig. 12-23) in the radiocapitellar joint or proximal radioulnar joint may also prevent complete reduction of the radial head.¹³⁹ Morris⁸⁶
described a patient in whom reduction of the radial head was obstructed
by radial nerve entrapment between the radial head and ulna.

Surgical Approach. The most direct approach to the radiocapitellar joint is from the posterolateral aspect of the elbow (Fig. 12-24).
The interval between the anconeus and the extensor carpi ulnaris, using
the distal portion of a Kocher incision, provides sufficient exposure
of the radial head and the interposed structures.⁵²,¹²⁹
This approach protects the posterior interosseous nerve when the
forearm is pronated. A more extensile approach was described by Boyd.²⁰
This exposure is begun by making an incision following the lateral
border of the triceps posteriorly to the lateral condyle and extending
it along the radial side of the ulna (see Fig. 12-24).
The incision is carried under the anconeus and extensor carpi ulnaris
in an extraperiosteal manner, elevating the fibers of the supinator
from the ulna. This carries the approach down to the interosseous
membrane, allowing exposure of the radiocapitellar joint, excellent
visualization of the orbicular ligament, access to the proximal fourth
of the entire radius, and approach to the ulnar fracture all through
the same incision.²⁰,²¹,¹²¹
In addition, elevation of the extensor-supinator mass from the lateral
epicondyle allows more proximal exposure of the dislocated radial head
if entrapped behind the capsule.

Postoperative Care. A
bivalved long-arm cast is used for 4 to 6 weeks with the forearm in
slight supination and the elbow flexed 90 to 110 degrees depending on
the degree of swelling. Radiographs are obtained every 1 to 2 weeks
until fracture healing. Intramedullary hardware is removed with
fracture healing. Plate and screw fixation is removed after 6 months
only if it is irritating. Home rehabilitation is begun at 6 weeks and
return-to-sports is dependent on restoration of motion and strength.

Posterior Monteggia fracture-dislocations are uncommon, accounting for 6% of Monteggia lesions in children,⁷³ and are usually found in older patients⁹⁷ who have sustained significant trauma.³⁷,¹⁰⁸,¹⁰⁹

As with type I Monteggia lesions, the elbow region is
swollen but exhibits posterior angulation of the proximal forearm and a
marked prominence in the area posterolateral to the normal location of
the radial head. The entire upper extremity should be examined because
of the frequency of associated fractures.⁷¹,⁹⁷

Standard radiographic views of the forearm demonstrate
the pertinent features for classifying this fracture. The typical
finding is a proximal metaphyseal fracture of the ulna with possible
extension into the olecranon (Fig. 12-25).³⁷,⁹¹,¹³⁵ Midshaft fractures also occur, with an oblique fracture pattern.⁸,³⁷,⁹¹ The radial head is dislocated posteriorly or posterolaterally⁹
and should be carefully examined for other injuries. Accompanying
fractures of the anterior margin of the radial head have been noted.³⁷,⁹⁷ Initially,

these are subtle in children but can lead to progressive subluxation and make late reconstruction difficult (Fig. 12-26).

The cause of the type II Monteggia lesion is subject to debate. Bado⁹ thought the lesion was caused by direct force and sudden rotation and supination. Penrose¹⁰⁰
analyzed seven fractures in adults and noted that a proximal ulnar
fracture was the typical pattern. He postulated that the injury
occurred by longitudinal loading rather than direct trauma.¹²¹ Olney and Menelaus⁹¹ reported four type II lesions in their series of children’s Monteggia fractures. Three of these patients had proximal ulnar

fractures and one an oblique midshaft fracture, suggesting two different mechanisms of injury.

The mechanism proposed and experimentally demonstrated by Penrose¹⁰⁰
was that type II lesions occur when the forearm is suddenly loaded in a
longitudinal direction with the elbow flexed 60 degrees. He showed that
a type II lesion occurred consistently if the ulna fractured;
otherwise, a posterior elbow dislocation was produced (see Fig. 12-26).
A possible difference in bony strength of the ulna suggested a reason
for the high incidence of type II Monteggia fractures in older adults
and their rarity in children. Penrose¹⁰⁰ further noted that the rotational position of the forearm did not seem to affect the type of fracture produced.

Haddad et al.⁵⁴
described type II Monteggia injuries caused by low-velocity injuries in
six adults, five of whom were on long-term corticosteroid therapy. They
suggested that this supports the theory that the type II (posterior)
Monteggia injury is a variant of posterior elbow dislocation, in that
it occurs when the ulna is weaker than the ligaments surrounding the
elbow joint, resulting in an ulnar fracture before the ligament
disruption associated with dislocation occurs.

Nonoperative Treatment. As with type I injuries,
incomplete type II fractures usually have a satisfactory result after
closed reduction.⁷⁵,⁹¹,⁹⁸,¹⁰⁵,¹⁴³
The ulnar fracture is reduced by longitudinal traction in line with the
long axis of the forearm while the elbow is held at 60 degrees of
flexion (Fig. 12-27). The radial head may
reduce spontaneously or may require gentle, anteriorly directed
pressure applied to its posterior aspect. The elbow is extended once
the radial head is reduced and is immobilized in that position to
stabilize the radial head and allow molding posteriorly to maintain the
ulnar reduction.³⁴,⁹⁸,¹⁴¹ If the ulnar alignment cannot be maintained, an intramedullary K-wire should be used.

Operative Treatment. Treatment goals are stable
concentric reduction of the radial head and alignment of the ulnar
fracture. When there is an unstable, complete ulnar fracture,
percutaneous intramedullary fixation or open reduction and internal
fixation with plate and screws are used similar to type I
fracture-dislocations.⁹⁶,¹⁰¹
The radial head should be reduced by open technique if there is
interposed tissue or if it is accompanied by a fractured capitellum or
radial head.

Lateral swelling, varus deformity of the elbow, and
significant limitation of motion, especially supination, are the
hallmarks of lateral (type III) Monteggia fracture-dislocations. Again,
these signs can be subtle and missed by harried clinicians.

Type III lesions are common in children, second in frequency to anterior type I Monteggia fracture-dislocations.⁹,⁸⁷,⁹¹,⁹⁸,¹⁴³ Injuries to the radial nerve, particularly the posterior interosseous branch, occur more frequently with this lesion.¹³,¹¹¹,¹²⁴
Open reduction of the radial head may be necessary because of
interposition of soft tissue between it and the ulna or capitellum.¹³,⁶⁰,¹¹¹,¹³³,¹⁴⁵,¹⁴⁷

The radial head may be displaced laterally or anterolaterally.⁹⁶,⁹⁸ The ulnar fracture often is in the metaphyseal region,⁹,¹³,⁶⁰,⁶⁶,⁸⁶,⁹⁸,¹¹¹,¹⁴⁷ but it can also occur more distally.⁹¹,¹⁴³,¹⁴⁵
Radial angulation at the fracture site is common to all lesions,
regardless of the level. Radiographs of the entire forearm should be
obtained because of the association of distal radial and ulnar
fractures with this complex elbow injury.¹³⁵
As with all Monteggia injuries, the acute lesion can be missed if
proper radiographs are not obtained and appropriate close examination
of the studies are not performed.

Wright¹⁴⁷ studied
fractures of the proximal ulna with lateral and anterolateral
dislocations of the radial head and concluded that the mechanism of
injury was varus stress at the level of the elbow, in combination with
an outstretched hand planted firmly against a fixed surface (Fig. 12-28).
This usually produces a greenstick ulnar fracture with tension failure
radially and compression medially. The radial head dislocates
laterally, rupturing the annular ligament. Hume⁶⁰
suggested that the injury may be the result of hyperextension of the
elbow combined with pronation of the forearm. Other authors confirmed
the mechanism of varus force at the elbow as the cause of these
injuries.⁹,³⁴,⁸⁷,⁹⁸,¹³⁴
The direction of the radial head dislocation is probably determined by
the rotation and angulation force applied simultaneously with the varus
moment at the elbow.⁸⁷

Nonoperative Treatment. Nonoperative treatment by
manipulative closed reduction is usually effective in pediatric
patients with metaphyseal, incomplete, or plastic deformation fractures.⁹,³⁴,⁴⁶,⁶⁰,⁷⁵,⁸⁷,⁹¹,⁹⁸,¹³⁴,¹⁴³,¹⁴⁷ However, the rate of operative treatment has been reported to be as high as 12%.⁹¹ The reduction maneuver for nonoperative type III lesions is shown in Fig. 12-29.

Closed Reduction. Reduction is carried out by reversing the mechanism of injury.³⁴,⁸⁷,⁹⁸,¹³⁵
The elbow is held in extension with longitudinal traction. Valgus
stress is placed on the ulna at the site of the fracture, producing
clinical realignment (Fig. 12-30). The radial head may spontaneously reduce or need assistance with gentle pressure applied laterally (see Fig. 12-29). Reduction sometimes produces a palpable click.¹³⁵
Ulnar length and alignment must be maintained to ensure a stable radial
head. Fluoroscopic radiographs are obtained to confirm radial head
reduction.⁸⁴ Any malalignment of the
radiocapitellar joint in any view implies the possibility of interposed
tissue or persistent malalignment of the ulna fracture. The angular
alignment of the ulna must be anatomic to allow and maintain reduction
of the radial head.⁴⁴

Reduction is maintained by a long-arm cast with the
elbow in flexion. The degree of flexion varies depending on the
direction of the radial head dislocation. When the radius is in a
straight lateral or anterolateral position, flexion to 110 to 120
degrees improves stability.³⁷,⁸⁷,¹⁰⁵,¹⁴³ If there is a posterolateral component to the dislocation, apposition of only 70 to 80 degrees of flexion has been recommended.¹³⁵
Of note, it can be difficult to assess continued reduction of the
radial head on the AP view radiographically in a cast with the elbow
flexed.

Forearm rotation in the cast is usually in supination,
which tightens the interosseous membrane and further stabilizes the
reduction.⁹,³⁴,⁸⁷,¹⁴³ Some have suggested positions of immobilization from pronation¹³⁴ to slight supination.¹³⁵ Ramsey and Pedersen¹⁰⁵
recommended neutral as the best position of rotation to avoid loss of
motion; their patients showed no loss of reduction using this position.

Radiographic Evaluation. Radiographs are taken in the AP
and lateral planes to confirm the reduction of the radial head and
assess the ulnar alignment. Up to 10 degrees of ulnar angulation is
acceptable in younger children, provided the radial head reduction is
concentric and stable. Range-of-motion testing of stability is
appropriate and necessary with plastic deformation fractures since AP
radiographs in the cast will be difficult to assess.

Immobilization. A long-arm cast is applied with a valgus
mold over the fracture site. Immobilization is usually in 90 to 100
degrees of flexion for lateral Monteggia lesions and 60 to 80 degrees
of flexion for posterolateral dislocations. The fracture and radial
head reduction need to be truly stable for cast immobilization since
postreduction radiographs are hard to interpret accurately.

Postreduction Care. Cast immobilization is continued
until fracture and soft tissue healing, usually by 6 weeks. Home
rehabilitation is performed until restoration of motion and strength.
Final radiographs are obtained with full restoration of motion and
strength to be certain there is anatomic reduction of the proximal
radioulnar and radiocapitellar joints.

Operative Treatment. Surgical intervention has two
goals: reduction and stabilization of both the ulnar fracture and the
radial head. If there is an inability to obtain and maintain anatomic
alignment of the ulnar fracture, proximal radioulnar, and
radiocapitellar joints, then operative treatment is indicated.

Ulnar Stabilization. Ulnar
malalignment may prevent anatomic relocation of the radial head. The
ulnar fracture can usually be reduced closed, but open reduction may be
necessary because of interposed tissue.

Stabilization of the ulna is necessary to prevent
recurrent lateral dislocation of the radial head. Persistent varus
alignment or radial bow, particularly with oblique fractures, may lead
to recurrent subluxation of the proximal radius (Fig. 12-31).⁴⁴,⁹¹ Anatomic reduction of the ulna and fixation with plates and screws⁴⁴ or intramedullary wires⁸ will yield excellent results.

Radial Head Reduction.
Failed closed reduction of the radial head with anatomic alignment of
the ulna fracture implies interposition of soft tissue, which is
repaired through a Boyd approach (see Fig. 12-24).²⁰,¹⁴⁵ This allows removal of the interposed tissues¹³⁹,¹⁴⁵ and repair or reconstruction of the annular ligament and the periosteum of the ulna, if necessary (Fig. 12-32),¹⁴,²³,⁴⁴,⁴⁶,¹²¹,¹³³ The surgical technique is essentially the same as previously described for a type I Monteggia fracture-dislocation.

Postoperative Care. Postoperative care is the same as for a fracture treated nonoperatively.

The appearance of the limb with a type IV lesion is
similar to that of a type I lesion. More swelling and pain are present
because of the magnitude of force required to create this complex
injury. Particular attention should be given to the neurovascular
status of the limb, anticipating the possible increased risk for a
compartment syndrome. Although this injury is uncommon in general and
rare in children, the radiocapitellar joint should be examined in all
midshaft forearm fractures to avoid missing the proximal radioulnar
joint disruption (Fig. 12-33). Failure to recognize the radial head dislocation is the major complication of this fracture.¹²

The anterior radial head dislocation is similar to that in a type I Monteggia lesion (Fig. 12-34). The radial and ulnar fractures usually are in the middle third,³⁵ with the radial fracture usually distal to the ulnar injury. They may be complete or greenstick.

Bado⁸ proposed that a
type IV lesion is caused by hyperpronation. Of the case reports
discussing the mechanism of injury, both hyperpronation⁴⁴ and a direct blow¹¹² have been postulated. Olney and Menelaus⁹¹
reported a single type IV lesion in their series but did not discuss
the mechanism. Type IV lesions appear to be caused by the mechanism
described for type I lesions.

This complex lesion has been treated by both closed⁹¹ and open⁹
techniques. Percutaneous intramedullary fixation of the radial and
ulnar fractures with flexible pins and closed reduction of the radial
head also have been described.⁴⁷,¹¹²

Clinical findings are similar to those for the
corresponding Bado lesion, with the common triad of pain, swelling, and
deformity.

As with the Bado types, careful radiographic study
should be made with at least two orthogonal views of the elbow in
addition to views of the forearm. Special views such as obliques should
be obtained to clearly delineate the associated injuries (e.g., radial
head or neck fractures, lateral humeral condyle fractures) and allow
adequate pretreatment planning.

The mechanism of injury by which the fracture occurs
helps define its equivalent type and is discussed in the sections on
the relevant Bado type.

As with the other Bado types, treatment focuses on two
general components of the lesion: ulnar fracture alignment and radial
head reduction. Associated injuries must be dealt with appropriately.

Ulnar Fracture. This fracture is treated as are other
Bado types. The method is dictated by the fracture pattern and location
and its stability after reduction.

Associated Injury. These associated fractures and
dislocations are evaluated and treated using principles based on the
particular injury. They are discussed thoroughly in other sections of
this chapter and book.

Treatment indications have ranged from the presence of a
chronic Monteggia lesion at anytime postinjury to only when there is
pain, restricted motion, and functional disability. That wide spectrum
of expert opinion makes individual case decision making difficult for
patients, parents, and clinicians. Blount¹⁹ and Fowles et al.⁴⁴
suggested that reconstruction provides the best results in patients who
have had a dislocation for 3 to 6 months or less. Fowles et al.⁴⁴ reported successful relocations up to 3 years after injury; Freedman et al.,⁴⁶
up to 6 years after injury. Throughout the literature, the appropriate
age for radial head reduction seems to be younger than 10 years.¹²⁷ Hirayama et al.⁵⁷
suggested that the procedure not be performed if there is significant
deformity of the radial head, flattening of the capitellum, or valgus
deformity of the neck of the radius. Seel and Peterson¹¹⁷
suggested that the age of the patient and the duration of the
dislocation are unimportant. Their criteria for surgical repair were
(i) normal concave radial head articular surface and (ii) normal shape
and contour of the ulna and radius (deformity of either correctable by
osteotomy). They treated seven patients ranging in age from 5 to 13
years for chronic dislocations that had been present from 3 months to 7
years. All seven were fully active with no elbow pain or instability at
an average of 4 years after surgery.

Although they recommended surgical treatment of chronic
Monteggia lesions in children because of the long-term sequelae,
Rodgers et al.¹¹² cautioned that the
results of reconstructive procedures are unpredictable and associated
with a number of complications including malunion of the ulnar shaft,
recurrent radiocapitellar subluxation, and radial and ulnar neuropathy.

At present, most authors advocate surgical
reconstruction of a chronic Monteggia when (i) the diagnosis is made
early, (ii) there is preservation of the normal concave radial head and
convex capitellum, (iii) especially when there is progressive deformity
(i.e., valgus), loss of motion, and pain, and, (iv) the patient and
family are well aware of the concerns with operative reconstruction.

Descriptions of surgical reconstruction for pediatric
chronic Monteggia lesions have been variable in terms of (i) annular
ligament repair or reconstruction,⁵³ (ii) ulnar osteotomy alone⁶² or in combination with ligament reconstruction,³⁰,⁵⁹ and (iii) radial osteotomy.²⁹ The technique for delayed reduction of the radial head in a Monteggia fracture-dislocation is attributed to Bell-Tawse,¹⁴ who used the surgical approach described by Boyd.²⁰ Other surgical approaches have been developed.⁵²,¹²⁹

Annular Ligament Repair or Reconstruction. Most but not
all authors advocate surgical repair or reconstruction of the annular
ligament in conjunction with an ulnar osteotomy for a pediatric chronic
Monteggia lesion. Ligament repair or reconstruction without an
osteotomy is very rarely indicated.¹⁴⁶ Kalamchi⁶³ restored stability after open reduction and osteotomy by utilizing the native annular ligament. Bell-Tawse¹⁴ used a strip of triceps tendon to reconstruct the annular ligament, as did Lloyd-Roberts⁷⁸ and Hurst.⁶¹ Bell-Tawse¹⁴
used the central portion of the triceps tendon passed through a drill
hole in the ulna and around the radial neck to stabilize the reduction
and immobilized the elbow in a long-arm cast in extension. Bucknill²³ and Lloyd-Roberts⁷⁸
modified the Bell-Tawse procedure by using the lateral portion of the
triceps tendon, with a transcapitellar pin for stability. The elbow was
immobilized in flexion. Hurst and Dubrow⁶¹
used the central portion of the triceps tendon but carried the
dissection of the periosteum distally along the ulna to the level of
the radial neck, which provided more stable fixation than stopping
dissection at the olecranon as described by Bell-Tawse.¹⁴
They also used a periosteal tunnel rather than a drill hole for
fixation of the tendinous strip to the ulna. Other authors have used
other soft tissues for reconstruction, including the lacertus fibrous,²⁶ a strip of the forearm fascia,¹²⁰ palmaris longus free tendon graft,¹⁴² and free fascia lata graft.¹³⁸ Seel and Peterson¹¹⁷
described the use of two holes drilled in the proximal ulna. The holes
are placed at the original attachments of the annular ligament and
allow repair of the annular ligament (frequently avulsed from one
attachment and trapped within the joint) or reconstruction of the
annular ligament with triceps tendon. This technique secures the radial
head in its normal position from any dislocated position and allows
osteotomy for correction of any accompanying deformity of the ulna or
radius. Seel and Peterson¹¹⁷ noted that the Bell-Tawse procedure tends to pull the radius posterolaterally (Fig. 12-39)
and possibly constricts the neck of the radius, thereby potentially
limiting the growth of the radial neck (“notching”) and reducing
forearm rotation. Seel and Peterson¹¹⁷
placed a single drill hole obliquely across the ulna to exit medially
at the site of the medial attachment of the annular ligament on

the coronoid process of the ulna (Fig. 12-40).
The tendon was routed through the tunnel, brought around the neck, and
sutured to the lateral side of the ulna. With this construct, the
direction of stability was posteromedial. The use of two drill holes to
secure the annular ligament or other reconstructive tendon at both
normal attachments of the annular ligament on the ulna achieved a more
normal posteromedial holding force on the neck of the radius.
Alternatives to holes drilled in the bone are small bone staples or
bone-anchoring devices.

Osteotomy. Most surgeons advocate an ulnar osteotomy,
with or without ligament repair/reconstruction, for a pediatric chronic
Monteggia lesion. Various types of osteotomies have been used to
facilitate reduction of the radial head and prevent recurrent
subluxation after annular ligament reconstruction (Fig. 12-41). Kalamchi⁶³
reported using a “drill hole” ulnar osteotomy to obtain reduction of
the radial head in two patients. Minimal periosteal stripping with this
technique allowed the osteotomy to heal rapidly. Hirayama et al.⁵⁷
used a 1-cm distraction ulnar osteotomy approximately 5 cm distal to
the tip of the olecranon with plate-and-screw fixation, but
complications with loosening and plate breakage occurred. Mehta⁸²,⁸³
used an osteotomy of the proximal ulna stabilized with bone graft. In
neither series was annular ligament repair done. Oner and Diepstraten⁹²
suggested that ulnar osteotomy is not necessary in type I lesions
(anterior dislocation), but in type III lesions (anterolateral
dislocation) recurrent subluxation is likely without osteotomy.
Freedman et al.⁴⁶ reported a delayed
open reduction of a type I Monteggia lesion without annular ligament
reconstruction but with ulnar osteotomy, radial shortening, and
deepening of the radial notch of the ulna.

Inoue and Shionoya⁶²
compared the results of simple corrective ulnar osteotomy in six
patients with those of posterior angular (overcorrected) osteotomy in
six others, and found that better clinical outcomes were obtained with
the overcorrected, angular osteotomy. Tajima and Yoshizu,¹³²
in a series of 23 neglected Monteggia fractures, found that the best
results were obtained by opening wedge osteotomy of the proximal ulna
without ligament reconstruction.

Exner³⁹ reported that
in patients with chronic dislocation of the radial head after missed
type I Monteggia lesions, reduction was successfully obtained with
ulnar corticotomy and gradual lengthening and angulation of the ulna
using an external fixator. Another option for type IV old Monteggia
fracture is a shortening

osteotomy of the radius, usually indicated for angulation of the radius without angulation of the ulna.

After wound closure, a bivalved (including Webril
[Kimberly Clark, Chantilly, VA]) long-arm cast is applied with the
forearm in 60 to 90 degrees of supination and the elbow flexed 80 to 90
degrees. The cast is maintained for 4 to 6 weeks and is then changed to
a removable bivalve to allow active motion, especially pronation and
supination. Elbow flexion and extension return more rapidly than rotary
motion of the forearm which may take up to 6 months to improve, with
pronation possibly limited, though minimally, permanently.¹¹² Final desired result is not determined until radiographs are anatomic with full restoration of motion.

The literature reflects a 10% to 20% incidence of radial
nerve injury, making it the most common complication associated with
Monteggia fractures.⁶⁰ It is most commonly associated with types I and III injuries.¹⁴,⁸⁹,¹¹⁸
The posterior interosseous nerve is most commonly injured because of
its proximity to the radial head and its intimate relation to the
arcade of Frohse. The arcade may be thinner and therefore more pliable
in children than in adults.¹²² In
addition, the periosteum is much thicker in pediatric patients. This
may account in part for the rapid resolution of the nerve injury in
children.

A radial nerve injury in a child is treated expectantly.
Nerve function usually returns by 12 weeks after reduction, if not
sooner.¹²³,¹²⁵ A review of a series of children’s Monteggia lesions⁹¹
recommends waiting 6 months before intervention for a posterior
interosseous nerve injury. Most series report 100% resolution in both
fractures treated promptly and those treated late.¹,⁶,⁷⁶

Two reports⁸⁶,¹²⁰
of irreducible Monteggia fractures caused by interposition of the
radial nerve posterior to the radial head documented return of function
approximately 4 months after the nerve was replaced to its normal
anatomic position and the radial head was reduced. Morris,⁸⁶
in cadaver studies, showed that significant anterior dislocation of the
radial head and varus angulation of the elbow allowed the radial nerve
to slide posterior to the radial head and, with subsequent reduction of
the radial head, become entrapped. If a chronic reconstruction is
undertaken in the presence of a persistent radial nerve lesion, it is
highly recommended that radial nerve exploration and decompression be
performed before joint débridement. Rodgers et al.¹¹³ cited a partial nerve injury during similar circumstances that was then microscopically repaired with full recovery. Rang¹⁰⁶ acknowledged the same experience to the author in an open educational forum.

Bryan²² reported one
adult with an ulnar nerve lesion associated with a type II Monteggia
lesion with spontaneous resolution. Stein et al.¹²⁵
reported three combined radial and ulnar nerve injuries, two of which
underwent exploration and decompression for functional return of the
nerve.

Median nerve injuries are uncommon with Monteggia fractures, but injury to the anterior interosseous nerve has been reported.¹⁴²,¹⁴³ Stein et al.,¹²⁵
in their report specifically examining nerve injuries in Monteggia
lesions, reported no median nerve deficits. Watson and Singer¹⁴²
reported entrapment of the main trunk of the median nerve in a
greenstick ulnar fracture in a 6-year-old girl. Completion of the
fracture was necessary for release of the nerve. At 6 months after
surgery, there was full motor recovery but sensation was slightly
reduced in the tips of the index finger and thumb.

Tardy radial nerve palsy associated with radial head dislocation has been infrequently reported.¹,⁶,⁵⁸,⁷⁶,¹⁴⁸
Although reported treatment has varied, excision of the radial head
with exploration and neurolysis of the nerve generally produced good
results,¹,⁶ while exploration of the nerve alone produced variable results.⁵⁸,⁷⁶ Yamamoto et al.¹⁴⁸ combined radial head resection and nerve exploration with tendon transfers, producing good results in two patients.

Two patterns of ossification after Monteggia
fracture-dislocations have been noted radiographically: around the
radial head and myositis ossificans. Ossification around the radial
head and neck¹⁴,⁶⁰,⁷⁶,⁷⁸,¹²⁶,¹²⁸
appears as a thin ridge of bone in a cap-like distribution and may be
accompanied by other areas resembling sesamoid bones; they resorb with
time. Ossification may also occur in the area of the annular ligament,³⁶
including in a chronic Monteggia with a displaced annular ligament.
Elbow function generally is not affected by the formation of these
lesions¹⁴,⁶⁰,⁷⁸,¹²⁶,¹²⁸

as long as the radial head and neck are anatomically reduced.

The other form of ossification is true myositis
ossificans, reported to occur in approximately 3% of elbow injuries and
7% of Monteggia lesions in adults and children.⁹⁰
Myositis ossificans has a good prognosis in patients younger than 15
years of age, appearing at 3 to 4 weeks after injury and resolving in 6
to 8 months. Its occurrence is related to the severity of the initial
injury, association with a fractured radial head, the number of
remanipulations during treatment, and passive motion of the elbow
during the postoperative period.⁹⁰,¹³⁷