MONTEGGIA FRACTURE

CLINTON F. PICKETT D.O. Orthopaedic Resident

KIRK DABNEY M.D. Attending Orthopaedic Surgeon

April 15, 1996

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE.

CASE HISTORY:

L.S. , a 12 year-old right- hand dominant female presented to this institution complaining of right forearm pain. The patient stated that while playing basketball she fell down and another player subsequently fell onto her right arm. The patient was brought to the emergency department for evaluation.

Physical exam revealed an alert white female . The right upper extremity was neuro-vascular intact. The volar surface of the proximal forearm had two small puncture wounds . Radiographs revealed a comminuted fracture of the proximal one-third of the ulna with over-riding of the fragments. The radial head was dislocated anteriorly .

The patient was taken to the operating room where the wounds were extended with an incision and irrigated with approximately six liters of fluid .After irrigation and debridement, open reduction and fixation of the ulna with a four -hole plate was performed. The radial head was reduced closed . The upper extremity was then splinted with eighty degrees of flexion and full supination. The patient was admitted for dressing changes ,observation ,and IV antibiotics. Three days later she was discharged to home after application of a long-arm cast.

Monteggia Fractures

INCIDENCE

0.4% of all forearm fractures.

In 1814 Giovanni Battista Monteggia published a report of two cases of traumatic lesions characterized by a fracture of the proximal one-third of the shaft of the ulna associated with an anterior dislocation of the radial-humeral joint.

Malgaigne described the injury as a dislocation of the radius which accompanied a fracture of the ulna at any level. He noted that

When there is a fracture of only one bone of the forearm with angulation or overlap there must be a subluxation of one or the other radial-ulnar joint.

When taking radiographs of the fracture , the nearest joint must also be included.

When a fracture is unstable in this area it is an indication for internal fixation.

CLASSIFICATION

Bado classified four types of monteggia lesions and stated that the radial head would dislocate in the direction of the apex of angulation of the ulna.

1. Type I monteggia lesion -anterior dislocation of the radial head . The ulna shaft is fractured with apex angulation anteriorly. Mechanism of injury is described as direct trauma to posterior ulna, or fall onto an outstretched arm with the momentum of the body causing forced pronation of the forearm. Another mechanism described is falling on an outstretched arm with the elbow hyperextended. This pattern is most common type.
2. Type II. monteggia lesion -posterior or posterior-lateral dislocation of the radial head. The ulna shaft is fractured with apex posterior. This lesion is thought to be due to a rotational force in supination or direct trauma of the forearm in the supinated position. This pattern is rare in children and is frequently an open fracture.
3. Type III monteggia lesion Lateral or anterior-lateral dislocation of the radial head with fracture of the ulnar metaphysis. This pattern is unusual and all reported cases have been in children. The mechanism of injury may be direct trauma over the inner aspect of the elbow with or without a rotational force. This causes an adduction force displacing the radial head anteriorly. Supination or pronation forces added will cause posterior-lateral or anterior-lateral dislocation.
4. Type IV monteggia lesions Anterior dislocation of the radial head with a fracture of the proximal radius. The ulna has a apex anterior angulated fracture.

Monteggia Equivalents.

• Anterior dislocation of the radial head with plastic deformation of the ulna.
• Fracture of the ulnar diaphysis with a fracture of the neck of the radius.
• Fracture of the ulnar diaphysis with a fracture of the proximal third of the radius proximal to the ulnar fracture
• Fracture of the ulnar metaphysis with anterior dislocation of the radius.
• Fracture of the ulnar diaphysis with anterior dislocation of the radial head and fracture of the olecranon
• Fracture of the ulnar metaphysis with fracture of the neck of the radius
• Posterior dislocation of the elbow and fracture of the ulnar diaphysis , with or without a fracture of the proximal radius.

DIAGNOSIS

1. I It is essential to insist on a true lateral to evaluate the radial-humeral joint. A line drawn through the center of the radial head should pass through the center of the capitellum in lateral flexion or extension views.
2. II With less severe injuries there may be a minimally angulated greenstick fracture and a dislocation may be missed.

SURGICAL ANATOMY

1. The capsule of the elbow joint blends with the annular ligament. The annular ligament is attached to the anterior and posterior margins of the ulnar notch. The annular ligament is the most important structure in maintaining the radial head in alignment.In children the radial head may pull out of the annular ligament, whereas in adults the annular ligament usually tears.
2. The quadrate ligament extends between the neck of the radius and the inferior border of the radial notch of the ulna. This structure may be disrupted when excessive rotation of the forearm occurs.
3. The interosseous membrane fibers course from the radius to the ulna in an oblique fashion . The fibers are taut in supination and lax in pronation.
4. Radial collateral ligament attaches to the annular ligament.

TREATMENT

• Approximately 90% of these injuries in children have good results with closed treatment.
• Open reduction is required if adequate closed reduction cannot be achieved. This occurs more frequently in older children or when there has been a delay in diagnosis.
• Type I fractures. -Apply traction with the forearm extended and supinated . If the radial head does not spontaneously reduce with this motion then the elbow is gently flexed while pressure is applied anteriorly over the head of the radius. After reduction is attained the elbow is immobilized in full supination and 100degrees of flexion if possible.
• Type II fractures are reduced with the forearm in extension and supination, and pushing with the thumb over the posterior aspect of the radial head. Bado suggests placing the elbow in 90 degrees of flexion and applying gentle traction and pronation . The arm is then immobilized in extension for four weeks then placed in a long arm cast with the elbow flexed for an additional 2 weeks.
• Type III fractures. Closed reduction is performed by applying traction and putting abduction strain on the extended elbow. Supinating the forearm while applying pressure on the lateral side of the radial head. The arm is then placed in a long-arm cast in flexion and supination for 6 weeks.
• Type IV fractures are more difficult to reduce by closed means. If the ulna fracture is unstable plate fixation should be used instead of intramedullary pinning. Plating of the radial fracture may be needed to maintain the reduction. Some authors have used pins and plaster to maintain a closed reduction.
• If fracture is unstable intramedullary fixation of the ulna with a K-wire or a Rush rod inserted percutaneously in the younger child. Older children may require plating .
• If the radial head will not reduce, there may be interposition of the annular ligament or osteocartilaginous fragments. Using a posterior approach to the elbow, both components of the monteggia lesion can be approached. If the annular ligament cannot be repaired it can be reconstructed using triceps fascia .
• Many authors condemn transcapitellar pinning of the radial head. Cross pinning of the radius to the ulna increases risk of a cross-union.
• Leaving the radial head dislocated will result in progressive valgus deformity and collateral ligament instability of the elbow with restricted motion.

COMPLICATIONS

• Decreased range of motion -Usually closed treatment results less loss of motion
• Overlooked wrist trauma -Forearm fractures should increase suspicion of additional wrist or elbow pathology.
• Redislocation of radial head -- may occur after reconstruction . May also be due to interposition of the annular ligament or the radial nerve.
• Heterotopic ossification -if it does not affect function do not remove it.
• Persistent dislocation of the radial head and healed angular deformity of the ulna. May need to osteotomize the ulna and reconstruct the annular ligament.
• Nerve impingement -posterior interosseous nerve most common. Nerve is tethered as it passes under the fibrous arch of the supinator and arcade of Frohse. Radial nerve palsy with anterior dislocation of the radial head has been reported. Function usually recovers in 8-12 weeks . Initially conservative treatment is indicated. If no return of function is seen in 3 months surgical exploration is indicated.

REFERENCES

1. Letts M. , Locht R., Wiens J.;Monteggia Fracture Dislocations in Children JBJS 67B Nov 1985
2. Wiley J.J. ,Galey J.P. Monteggia Injuries In Children JBJS vol. 67B Nov 1985
3. Armstrong P.F., Joughin V.E., Clarke H.M. Pediatric fractures of the forearm, wrist, and hand Skeletal Trauma 1994 W.B. Saunders
4. King R. E. Fractures of the shafts of the radius and ulna Rockwood and Green Volume 3 1991 Lippincott
5. Bado, J.L., Monteggia Lesion, CORR 50, Jan-Feb, 1967.