Ulnar component surface finish influenced the outcome of primary Coonrad-Morrey total elbow arthroplasty

Abstract

Background: Controversy remains regarding the mechanisms leading to ulnar loosening after elbow replacement. We therefore assessed the loosening rate of the ulnar component as a function of the surface finish of a commonly used implant design.

Materials and methods: This study included 3 groups who received implants with 3 different surface finishes: sintered beads (278 components), polymethylmethacrylate precoating (219 components), and plasma-sprayed beads (205 components).

Results: The 3 groups who received the implants did not differ statistically in age, sex, or underlying diagnosis. The rates of mechanical failure for the sintered, precoated, and plasma-sprayed ulnar components were 6.8%, 12.8%, and 0%, respectively. The 7-year Kaplan-Meier survival rates free of mechanical failure were 93.1% for the sintered-beads group, 83.1% for the precoated group, and 100% for the plasma-sprayed group. Failed precoated ulnar components often failed early and exhibited typical features, including proximal debonding and severe focal or global osteolysis, sometimes leading to periprosthetic insufficiency fractures.

Conclusion: Precoating the ulnar component with polymethylmethacrylate can lead to an increased rate of loosening and severe osteolysis. A plasma-sprayed ulnar component is associated with a very low mechanical failure rate with surveillance of less than 10 years.