A hinged or articulated elbow external fixator is recommended for patients with elbow instability1, as a protective device following extensive capsular release of elbow contractures2, after ligamentous reconstruction3, for distraction interposition arthroplasty4, and in the management of complex elbow fracture-dislocations5. The hinged external fixator permits early postoperative elbow mobilization while maintaining elbow stability. There is a growing recognition of the value of and indications for articulated external fixation of the elbow6, despite the possibility of serious complications. Cheung et al.6 classified complications related to hinged external fixators of the elbow as major and minor. Minor complications, which occurred in 15% of patients, included local erythema and nonpurulent pin-site drainage lasting longer than five days and the need for skin release to decrease tension adjacent to the pins. Major complications, which occurred in 10% of patients, included purulent pin-site drainage, fixator malalignment, pin loosening, and deep infection. Although cases of transient radial nerve palsy are described in the literature1,7, to the best of our knowledge no permanent radial nerve palsy has been documented following application of a hinged external fixator. We present three cases of radial nerve palsy due to complete nerve disruption after application of a hinged external fixator for the treatment of complex elbow injuries.
The patients were informed that data concerning their cases would be submitted for publication, and they consented.
Case 1. A forty-seven-year-old male gardener fell on the right, dominant arm. No fracture or dislocation was noted. Seven years later, ulnar nerve decompression with a medial epicondylectomy was performed elsewhere (i.e., not at our hospital) to treat posttraumatic irritation of the ulnar nerve. Because the symptoms persisted postoperatively, the patient was seen by an elbow specialist at another institution and was diagnosed with marked medial and lateral elbow instability. Reconstruction of the medial and lateral ligaments was performed with use of semitendinosus tendon autografts, the ulnar nerve was transposed anteriorly (subcutaneously), and the elbow was stabilized by placing a hinged external fixator (Dynamic Joint Distractor II [DJD II]; Stryker Trauma, Selzach, Switzerland). The pins were placed percutaneously. Complete radial nerve palsy was noted immediately postoperatively. The external fixator was removed four weeks later. Clinically and electrophysiologically, the level of injury was localized near the division of the sensory and posterior interosseous nerves in the area of the distal humeral pin. Twelve months postoperatively, there were no detectible sensory radial nerve action potentials. The extensor carpi radialis, extensor digitorum communis, and abductor pollicis longus muscles had high spontaneous activity but no voluntary activity, findings that were highly suspicious for a complete lesion of the common radial nerve.
The patient was referred to our institution for an eventual radial nerve reconstruction with or without tendon transfer, but he refused any further surgical treatment.
Case 2. A seventy-four-year-old man fell on the left, nondominant arm and sustained a simple posterior elbow dislocation (without a fracture). After closed reduction at another hospital (i.e., not ours), the elbow remained unstable without any neurological deficit. Because the patient had persistent instability, open repair of the radial and ulnar collateral ligaments was performed, but the elbow remained unstable. A hinged external fixator (DJD II) was applied. The humeral half-pins (3 mm, threaded) were placed percutaneously in the manner proposed by the manufacturer8, through a small incision, tunneling until bone contact was made, and hand drilling of the pin.
Postoperatively, complete radial nerve palsy was observed, and one day later surgical exploration revealed a complete disruption of the radial nerve, with loss of substance of >4 cm at the level of the distal humeral pin, although this was not treated at that time. The external fixator was removed four weeks later, and the patient was referred to our institution because of persisting elbow instability and total loss of radial nerve function. The elbow had complex medial-lateral instability with anterior radial head dislocation in flexion and pronation. Initially, reconstruction of the anular ligament as well as the medial and lateral collateral ligaments was performed with use of autologous toe extensor tendon grafts. Five weeks postoperatively, after the patient had regained satisfactory stability and elbow mobility, tendon transfers for wrist, finger, and thumb extension were performed. The patient refused radial nerve reconstruction. Three months postoperatively, he had free and stable elbow motion with 145° of flexion, a 10° loss of extension, and 30° of active wrist extension.
Case 3. A fifty-five-year-old female architect fell while skiing and sustained a complex posterior dislocation of the right, dominant elbow with a comminuted radial head fracture (Fig. 1-A). Closed reduction and application of a long arm cast was performed at a local hospital. Immediately after reduction, redislocation of the elbow in the cast was noted, and the patient was referred to a trauma center, where two additional unsuccessful attempts at closed reduction and cast immobilization were carried out. Six weeks after the injury, she had a persistent dislocation. A closed reduction was not possible. Open reduction was done through a posterior approach. The medial and lateral collateral ligaments were reattached, and a radial head prosthesis was inserted. Because of the long-standing preoperative dislocation and incomplete restoration of stability intraoperatively following ligament repair, a hinged external fixator (DJD II) was applied (Fig. 1-B). As the fixator pins (3-mm half-pins) could not be placed through the posterior incision, they were placed percutaneously.
Figs. 1-A, 1-B, and 1-C Case 3. Fig. 1-A Complex posterior elbow dislocation with a radial head fracture. Fig. 1-B Postoperative anteroposterior and lateral radiographs. The elbow joint is reduced with the hinged external fixator and the radial head prosthesis in place. The distal humeral half-pin is 38 mm from the lateral epicondyle and the proximal pin is 99 mm from the lateral epicondyle.
Immediately postoperatively, a complete radial nerve palsy was noted, and electrodiagnostic testing four weeks after the surgery raised a high suspicion for a severe nerve injury. The radial nerve was explored during the removal of the external fixator five weeks postoperatively. A complete disruption of the nerve was found at the level of the distal humeral pin (Fig. 1-C). We performed secondary reconstruction three months later to avoid potential contamination from the fixator pins and to avoid risking the elbow stiffness that can result from the elbow immobilization that is necessary following nerve reconstruction and tendon transfer. Three months postoperatively, the elbow was stable with a 100° arc of elbow motion and nearly full forearm rotation. The 2 to 3-cm gap within the radial nerve was reconstructed by the interposition of four strands of sural nerve graft. At the same time, a pronator teres tendon transfer for wrist extension was accomplished. Three months after the nerve reconstruction and tendon transfer, the patient had 40° of active wrist extension and 10 kg of grip strength but no active thumb or finger extension.
Disruption of the radial nerve and its relationship to the distal humeral pinhole. The arrow indicates the proximal radial nerve stump, the arrowhead indicates the distal radial nerve stump, and the star indicates the pinhole.