Radial head arthroplasty with a modular metal spacer to treat acute traumatic elbow instability.

BACKGROUND The use of a metal radial head prosthesis to help stabilize an elbow with traumatic instability is appealing because internal fixation of multifragment, displaced fractures of the radial head is susceptible to either early or late failure. The newer modular prostheses are easier to size and implant, but their effectiveness has not been investigated, to our knowledge. METHODS Twenty-seven patients in whom a radial head replacement with a modular metal spacer prosthesis had been performed to treat traumatic elbow instability were evaluated with use of the Mayo Elbow Performance Index (MEPI), the American Shoulder and Elbow Surgeons Elbow Evaluation Instrument (ASES), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Radiographs were evaluated for arthrosis, periprosthetic radiolucency, and heterotopic ossification. RESULTS Seven patients underwent one or more subsequent operations to treat residual instability, heterotopic ossification and elbow contracture, ulnar neuropathy, or a misplaced screw. In two of these patients, the prosthesis was removed as part of an elbow contracture release or to treat infection. At an average of forty months postoperatively, elbow motion in the entire group of twenty-seven patients averaged 131 degrees of flexion with a 20 degrees flexion contracture, 73 degrees of pronation, and 57 degrees of supination. Stability was restored to all twenty-seven elbows, and twenty-two patients had a good or excellent result according to the MEPI. Seventeen patients had radiographic evidence of lucency around the neck of the prosthesis that was not associated with increased pain, thirteen patients had clinically inconsequential heterotopic ossification anterior to the radial neck, and nine patients had radiographic changes in the capitellum. CONCLUSIONS An intentionally loosely placed modular metal radial head prosthesis can help to restore stability in conjunction with repair of other fractures and reattachment of the lateral collateral ligament to the epicondyle in the setting of traumatic elbow instability with a comminuted fracture of the radial head. While a prosthesis that is too large can cause problems, lucencies around the stem of the intentionally loose prosthesis and most changes in the capitellum do not appear to cause problems, at least in the short term.