Mid-term clinical outcome comparison of long-stemmed monopolar osseointegrated and short-stemmed bipolar radial head prostheses.

INTRODUCTION: Comparative data to guide implant choice for radial head replacements are lacking. Here, we compared the clinical results achieved using two different types of radial head prostheses.
METHODS: Data from patients with comminuted radial head fractures (n = 66), who underwent radial head arthroplasty with either short-stemmed bipolar (n = 31, Group 1: rHead Small Bone Innovations/USA) or monopolar long-stemmed osseointegrated rigidly fixed (n = 35, Group 2: MoPyC Tornier/France) prostheses, were retrospectively reviewed. Patients were followed-up for an average of 42 months (16-64 months). Range of elbow motion, elbow stability, grip strength, and visual analog scale (VAS) pain were measured, and functional outcome assessed using the Mayo Elbow Performance Score, the Disability of Arm, Shoulder and Hand questionnaire, and the Broberg-Morrey Score. Complications were analyzed and revision surgeries recorded.
RESULTS: Most patients achieved good/excellent results for all assessed outcome variables, with no significant differences between the two implant groups; however, regardless of the prosthesis type, a mean extension deficit of 18.5° ± 1.7° remained at latest follow-up. Although complication and surgical revision rates were comparable (bipolar, 23%; monopolar, 18%), significantly more bipolar prostheses were explanted because of painful loosening (16% vs. 3%; p = 0.029).
CONCLUSION: Good to excellent mid-term results for radial head arthroplasty of comminuted radial head fractures can be achieved using both a bipolar and a monopolar radial head implant; however, the monopolar implant may be preferable, as it had a lower rate of painful loosening. Extension deficit occurs regularly. LEVEL OF EVIDENCE: Level III Retrospective comparative treatment study.