Influence of Coronoid fixation on the functional outcome and rate of complications in surgically treated acute complex elbow instability.

Introduction: Fractures of the coronoid commonly present in elbow fracture-dislocations. Despite the evidence that the coronoid plays an important role in elbow stability, there is still controversy on which fractures should be surgically fixed. The aim of this study is to compare the clinical outcomes and rate of complications of patients with elbow fracture-dislocations in which the coronoid was fixed or left untreated.

Materials and methods: Thirty-nine patients with an elbow fracture-dislocation involving a coronoid fracture were prospectively followed for an average of 90 months (range 24-190). According to Morrey´s classification there were 22 type II and 8 type III. Nine patients had an anteromedial fracture of the coronoid. In 24 patients the coronoid was repaired (suture fixation in 9, screws fixation in 10 and plate fixation in 5) and in 15 patients the coronoid was not fixed. In 18 patients the radial head was replaced and in 8 patients it was fixed. All patients underwent repair of the lateral ligament complex. Clinical evaluation was performed with the MEPS. Radiographically, the rate of coronoid nonunion was specifically analyzed. Postoperative neurological complications were recorded.

Results: At the most recent follow up, the average arc of flexion-extension was 120° (range 70°-140°) with a mean MEPS of 90 (range 25-100). No statistically significant differences were found in the MEPS and flexion-extension arc between the patients in whom synthesis was performed (117° ROM, and 89 MEPS) and those in whom it was not (122° ROM, 94 MEPS) (p = 0.42; p = 0.34). Coronoid fracture healing could be assessed in 36 patients: in 19 patients the coronoid was radiographically healed, and in 17 a nonunion was present, with no difference in the final clinical outcome between both groups. Nine patients, 6 of whom had undergone coronoid fixation, had a neurological complication related to the ulnar nerve.

Conclusions: Coronoid fractures affecting around 50% of its height can be treated without internal fixation as long as the rest of the osteo-ligamentous structures are adequately repaired. Osteosynthesis of the coronoid through a medial approach may carry a non-negligible risk of associated neurological injury.