Radial head prosthesis in complex elbow dislocations: effect of oversizing and comparison with ORIF.

Purpose: Elbow dislocations with complex elbow instability (CEI) and unstable radial head fractures require reconstruction by open reduction and internal fixation (ORIF) if possible or alternatively by a radial head prosthesis. The aim of this study was to determine the differential outcome of both strategies and to investigate the contribution of prosthesis-related radiographic factors such as oversizing on clinical outcome.
Methods: A total of 53 patients underwent ligament and coronoid refixation, and radial head reconstruction by ORIF (n = 18; group 1) or by monopolar modular prosthesis (n = 35; group 2). Patients were followed by the Mayo Elbow Performance Score (MEPS) and a radiological score including prosthesis oversizing, joint subluxation, ossifications, capitellar erosions, implant loosening and ulno-humeral osteoarthritis. To investigate the effect of oversizing, group 2 was subdivided by prosthesis overlenghtening ≥ 2 mm.
Results: A total of 42 patients (79.2%) could be followed for 3.0 ± 1.3 years with an average MEPS of 76.8 ± 17.2. Patients with ORIF had slightly better MEPS (82.1 ± 9.9) as compared with group 2 (74.7 ± 19.1) though three ORIF patients required an early conversion to prosthesis. In group 2, oversizing occurred frequently and 50% showed an overlenghtening ≥ 2 mm. Oversizing significantly decreased MEPS (63.2 ± 21.3 vs 84.7 ± 9.0; p = 0.001) and elbow range of motion and increased the occurrence of other radiological abnormalities and the risk for surgical revisions. The radiological score and prosthesis overlenghtening but not prosthesis diameter showed an inverse correlation with MEPS.
Conclusions: In CEI a radial head reconstruction with a prosthesis demonstrates similarly good clinical results as compared to ORIF in anatomically sized prosthesis, but prosthesis oversizing could induce other radiographic abnormalities with then deteriorated outcome.