Long-term outcomes after Instrumented Bone Preserving total elbow arthroplasty: a radiostereometric study with a minimum follow-up of 10 years.

Background: Aseptic loosening is a main concern in elbow arthroplasty. Evaluation of implant migration using radiostereometric analysis (RSA) might increase understanding of implant loosening. Previously, 2-year RSA results of 16 Instrumented Bone Preserving (IBP) elbow prostheses showed migration of the humeral component in the first weeks but most components stabilized within 6 months postoperatively. In follow-up, the present study evaluated long-term survival, the relation between early migration and survival, and the long-term migration and clinical outcomes.

Methods: Sixteen patients who received an IBP prosthesis were prospectively followed with a median follow-up time of 136 months (range 82-165). Migration was measured using RSA. Clinical results were described using the Elbow Function Assessment (EFA), Broberg and Morrey elbow functional rating index, Oxford Elbow Score (OES), and visual analog scale (VAS) for pain and satisfaction.

Results: Four patients underwent a revision within 10 years, and 2 more were planned for revision surgery after 14 years. Five patients died with their prosthesis in situ. Early migration was not associated with survival. Long-term migration patterns varied widely. Median EFA score was 58.5, Broberg and Morrey score was 50, and OES score was 32. Median VAS score for pain was 2 and that for satisfaction was 7.5.

Conclusion: Ten-year survival of the IBP total elbow prosthesis was 75%, decreasing to 63% after 14 years of follow-up. Long-term implant failure could not be predicted by 2-year migration results in this study. Although short-term clinical results were promising, long-term outcomes worsened in all patients.