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A 33-year-old machinery operator with an elbow “clunk” and pain

Issue: August 2014

ByMark S. Cohen, MD

ByLaith Al-Shihabi, MD

ByPeter N. Chalmers, MD

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A 33-year-old machinery operator presented to the office with a right elbow “clunk” and pain with motion following an elbow injury and surgery 5 months prior. At the time of his injury, he sustained an anterior Monteggia fracture-dislocation of his right elbow after his arm was caught in a pulley at work (Figure 1). He was seen and evaluated by an outside surgeon, who performed an open reduction and internal fixation (ORIF) of the ulna the day after the injury. At the time of surgery, reduction of the radiocapitellar joint was achieved after fixation of the ulna, and the ulnohumeral joint was reportedly stable through a range of motion.

Figure 1. Anteroposterior (a) and lateral (b) views of the right forearm demonstrate the patient’s original injury, an anteriorly displaced (Bado I) Monteggia fracture-dislocation of the elbow and forearm.

Images: Cohen M

While the patient’s early postoperative course was uneventful, the patient began to notice a painful popping of his elbow with forearm rotation several weeks following surgery. Radiographs revealed persistent anterior subluxation of the radial head. At that time, he was referred to our office for evaluation. His history was otherwise unremarkable. Examination revealed elbow motion measuring 25° to 130°, with near-full forearm rotation punctuated by a palpable and painful clunk at the radiocapitellar joint. The neurovascular exam was normal. On radiographs, the radial head was found to be nearly 100% anteriorly displaced relative to the capitellum, with apparent incomplete healing of the ulnar shaft (Figure 2).

Figure 2. Anteroposterior (a) and lateral (b) views of the patient’s forearm at presentation to the clinic demonstrates ulnar fixation with persistent anterior subluxation of the radial head. The ulna appears to be incompletely healed.

What is your diagnosis?

See answer on next page.

Ulnar malunion associated with chronic subluxation of the radial head

The patient had residual deformity following a Monteggia fracture-dislocation with continued incongruence of the radiocapitellar and proximal radioulnar joints. This resulted in a sensation of clunking as he attempted to rotate his forearm.

When viewed in isolation, the ulna appears to be well-reduced, yet the subluxation of the radial head indicates that the ulna may have been plated in a nonanatomic position. The dislocated radial head also suggests that the soft-tissue restraints to radial head subluxation, namely the annular and proximal interosseous ligaments, are most likely attenuated and/or nonfunctional.

Background and work-ups

Monteggia fractures of the forearm are characterized by fracture or deformation of the ulna along with a disruption of the proximal radioulnar joint (PRUJ). While this commonly manifests as a dislocation of the radiocapitellar joint, it is disruption of the PRUJ that distinguishes the Monteggia fracture from other injuries associated with radiocapitellar dislocation. This injury is rare in adults, accounting for less than 5% of forearm fractures. The radial head may displace anteriorly, posteriorly or laterally, but in contrast to its presence in children, 15% of Monteggia fractures in adults are associated with anterior dislocation of the radial head (up to 80% are displaced posteriorly). Monteggia injuries have historically been associated with high rates of complications, with up to 25% requiring a second operation within 12 months of the initial injury. Posterior radial head dislocations (Bado type II fractures), radial head fractures, and intra-articular fractures of the ulnohumeral joint are associated with the highest rates of complications and poor outcomes.

Peter N. Chalmers

The patient history and physical examination should focus on the mechanism of injury, along with any associated symptoms. While Monteggia fractures are typically the result of high-energy trauma, in children or adolescents they may be associated with much lower-energy mechanisms. Surgeons should rule out acute open injuries to the subcutaneous ulna. A careful neurological exam is critical, as up to 17% of these injuries are also associated with a neuropraxia of the posterior interosseous nerve (PIN), which can be stretched by displacement of the proximal radius. An examination of the uninjured side should be performed to assess the normal range of elbow flexion and extension along with forearm pronation and supination.

Understanding the normal and disrupted anatomy is critical to appropriately treat these injuries. The normal relationship between the radius and ulna is supported distally by the triangular fibrocartilage complex (TFCC), in the diaphysis by the interosseous ligament, and proximally by the quadrate and annular ligaments. Dislocation of the PRUJ requires disruption of the proximal ligaments, and may involve some portion of the proximal interosseous ligament as well. The bulk of the interosseous ligament and TFCC remain intact, however, and these structures will produce and maintain a stable reduction of the radiocapitellar and proximal radioulnar joints if an anatomic reduction and fixation of the ulna is achieved in most cases. To this end, preoperative neutral rotation anterior-posterior and lateral radiographs of both the elbow and forearm are necessary to evaluate and understand the ulna fracture. In the setting of ulnar comminution or bone loss, or when anatomic fracture keys are otherwise absent (such as in chronic injuries), contralateral radiographs may assist in the replication of the normal ulnar anatomy. Particular attention should be paid to the degree of posterior or medial-lateral bowing of the ulna as this this must be restored. Failure to do so risks malreduction of the ulna, which will result in a potentially unstable proximal radius. Advanced imaging is rarely necessary, though CT scanning can be valuable for complex articular fractures.

Treatment options

Given the need for anatomic alignment of the ulna and the value of early forearm motion to maximize function, closed treatment plays little role in the management of Monteggia fractures. Unless the patient’s medical condition precludes it, acute or chronic injuries should be surgically treated. Acutely, surgical treatment is directed at the ulna, which is reduced and plated, typically along its posterior subcutaneous border. Doing so should result in a stable closed reduction of the proximal radius. Indications for an open reduction of the radial head include interposed tissue preventing a closed reduction, or a PIN palsy that requires nerve exploration and decompression. Following reduction and fixation, the elbow should be taken through a full range of extension and flexion along with pronation and supination to test the stability of the PRUJ. Instability of the proximal radius suggests a subtle malreduction of the ulna. While the posterior ulna is relatively straight along its diaphyseal border, subtle posterior or medial-lateral bowing may be present proximally that must be restored.

Laith Al-Shihabi

In the setting of a chronic injury, multiple factors may contribute to continued instability of the proximal radioulnar joint. Closed reduction is likely to be impossible secondary to interposed scar tissue and contracted tissues surrounding the proximal radius, necessitating an open approach. As in the acute setting, restoration of anatomic length and alignment to the ulna is critical to permit this, and a corrective osteotomy of the ulna may be required if a malunion is identified. Slight over-correction of the ulna in the plane of the radial head dislocation may improve stability, but under-correction should be avoided. Lastly, with a chronic dislocation, even reproduction of the normal ulnar anatomy may not fully reduce the proximal radius secondary to stretching or attenuation of the proximal interosseous membrane and/or annular ligament. In these cases, reconstruction of the annular ligament should be considered in order to restore proximal ligamentous restraint to the radius.

Graft options for reconstruction include allograft, autograft palmaris longus and forearm fascia in children. This augments and reinforces the correction obtained by the ulnar osteotomy, but in isolation should not be considered sufficient to maintain reduction of the proximal radius. With time, any residual bony deformity will either stretch the reconstructed annular ligament or cause osteolysis of the radial neck.

Management of our patient

Figure 3. Intraoperative view depicting anterior subluxation of the radial head with pressure applied to it (a) is shown. The allograft is wrapped around the radial neck (b), and then docked in to an ulnar tunnel before tensioning on the opposite cortex using an EndoButton (c).

Based on the continued anterior dislocation of the radial head, our patient was diagnosed with a chronic Monteggia injury secondary to an ulnar malunion. The original ulna fixation apparently failed to recreate the patient’s native posterior ulnar bow, thus under-correcting the deformity of the fracture. The decision was made to proceed with revision ORIF of the ulna, along with annular ligament reconstruction using a semitendinosus allograft. The risks of surgery, including the potential for continued elbow pain, neurologic injury, failure of bony healing or reduction, and the risk of elbow stiffness were discussed with the patient at length.

Following induction of regional anesthesia, the patient’s previous surgical incision was utilized to expose and remove the ulnar plate. The ulna was found to be healed, necessitating an opening-wedge ulnar osteotomy at the site of the original fracture. Once this was performed, the radial head was easily reduced into the radiocapitellar and proximal radioulnar joints. The reduced radial head was then provisionally pinned using a 0.062 inch Kirschner wire. Pinning of the radial head assisted in determining the appropriate alignment of the ulna. A nine-hole, 3.5-mm locking compression plate, pre-bent to accommodate the opening wedge osteotomy, was then applied to the ulna. Distal radius bone graft was harvested and used to fill the defect opposite the plate. Following application of the ulnar plate, the radiocapitellar pin was removed. The radial head was found to be stable in a neutral position, but with pronation, it still had a tendency to anteriorly subluxate. At this time, the decision was made to proceed with annular ligament reconstruction.

An open approach to the radial head was used with a skin incision beginning along the distal supracondylar ridge and extending distally along Kocher’s interval. At the level of the forearm musculature, a longitudinal incision was made at the midline of the radiocapitellar joint between the extensor carpi radialis brevis tendon anteriorly and the extensor digitorum communis tendon posteriorly. Dissection was carried to the radial neck, which was found to abnormally subluxate anteriorly with applied pressure (Figure 3A). The displaced position of the proximal radius was utilized to pass a semitendinosus allograft tendon around the radial neck prior to its reduction, with one side of the tendon prepared using a running, locking nonabsorbable suture (Figure 3B). Graft passage around the radius was facilitated with a ligature passer.

Figure 4. Anteroposterior (a) and lateral (b) views of the forearm at final follow-up demonstrate healing of the ulnar osteotomy along with a stable, congruous reduction of the proximal radiocapitellar and radioulnar joints.

The graft ends were then passed beneath the extensor mechanism down to the subcutaneous border of the ulna, in the area of the lateral collateral complex insertion. A burr was utilized to place a unicortical hole within the lateral ulna at the level of the radial neck, sufficient in size to dock the allograft tendon arms. Opposite to this, a 2.5 mm drill hole was placed in the medial ulnar cortex through the tunnel. Using the ligature passer, the graft sutures were brought out through the medial cortical hole. Both ends of the allograft were docked into the tunnel with their sutures exiting the medial side. The graft was tensioned with the forearm in neutral rotation maintaining the reduction of the radius, and both sets of suture tails were then tied over an EndoButton (Smith & Nephew; London, United Kingdom) (Figure 3C). Care was taken not to over-tension the graft, which would theoretically risk limiting forearm rotation. At this point, the radiocapitellar joint was stable throughout a full range of elbow motion. The incisions were closed and the patient placed into a long-arm splint.

Follow-up

The patient’s splint was removed at the first postoperative visit, and he was started on a directed therapy program utilizing a lateral collateral ligament protecting protocol. A removable splint was utilized until 9 weeks postoperatively. At 3 months postoperatively, the patient discontinued his therapy program, with an arc of motion from 25° to 125° and full forearm rotation. At 6-months follow-up, the patient’s motion improved slightly to 20° to 130°, with equal grip strength on both sides.

Due to the slight flexion contracture, a program of static, progressive splinting was discussed with him. The patient declined this as he was satisfied with his motion and was able to return to work in a full-duty capacity. All postoperative imaging demonstrated a stable, reduced proximal radius with healing of the ulnar osteotomy (Figure 4), and the patient experienced no further problems of catching or clunking at the elbow.