A prospective multicenter clinical study of the Discovery elbow

Abstract

Background: Semiconstrained total elbow arthroplasty is used to improve elbow function and reduce pain. Although effective, high complication rates exist, with the polyethylene bushing especially susceptible to failure. The Discovery Elbow System (Biomet Inc, Warsaw, IN, USA) contains a spherical bearing designed to minimize polyethylene wear. This prospective, multicenter clinical study investigated the 4-year (mean) outcomes of this elbow.

Methods: From 2002 to 2009, 92 patients (71 women, 21 men; mean age, 63.9 years; range, 33.4-88.7 years) received 99 Discovery elbows at 4 centers. The study cohort was limited to 46 elbows with complete preoperative and minimum 2-year clinical (modified American Shoulder and Elbow Surgeons elbow score) and radiographic follow-up.

Results: Mean follow-up was 4.1 years (range, 2-5.9 years). All American Shoulder and Elbow Surgeons elbow score components improved significantly (P < .001). Mean flexion-extension arcs increased from 81° to 121° and pronation-supination arcs from 134° to 163° (P < .001). Loose locking screws in 2 elbows (first-generation screws), a loose polyethylene bearing in 1 (history of falls), and a condyle/bearing in 1 (deep infection) were exchanged. Among the 46 elbows, gross survivorship was humeral/ulnar components, 100%; condyles, 97.8%; bearings, 95.7%; and screws, 95.7%. One humeral component (2.2%) was radiographically loose but not revised. An additional elbow (elbow 47) that did not meet the criteria for inclusion (<2 years of follow-up) was revised due to a loose humeral component and was reported separately.

Conclusion: The Discovery elbow increased function and decreased pain with high survivorship at a mean of 4.1 years.

Keywords: Discovery elbow; outcomes; prostheses; semiconstrained; survivorship; total elbow arthroplasty.