The incidence of humeral bone resorption in uncemented reverse shoulder arthroplasty and the impact on functional outcomes

Abstract

BackgroundFull-thickness bone resorption around the humeral stem in shoulder arthroplasty is an increasingly recognized phenomenon, but the impact on outcomes remains unclear. This study aims to investigate prevalence of bone resorption in patients with the Zimmer-Biomet Comprehensive reverse shoulder arthroplasty and the impact on the functional outcomes. MethodsA retrospective analysis was carried out on 65 consecutive patients with primary reverse total shoulder arthroplasty using the Comprehensive Shoulder System from 2014 to 2020, with a minimum of 12-month follow-up. The prevalence of humeral bone resorption was graded from 0 to 4, and risk factors for these changes and their impact on functional outcomes were further investigated. ResultsThe majority of patients (75%) were female with an average age of 75 years (53-93), with an overall average follow-up of 26 months (12-60). Bone resorption occurred in 53 patients (82%), and full-thickness bone resorption occurred in only 8 patients (12%). Metaphyseal bone (zones 1 and 7) is mostly at the risk of high-grade resorption. There was no difference in the final Oxford Shoulder Score between patients who had differential resorption grades from 0 to 4 (P = .5742). None of the risk factors from the previous literature including age, sex, indication for surgery, rotator cuff tear and repair, and intramedullary occupation ratio of the implant showed any impact on the rate of resorption. ConclusionFull-thickness humeral bone resorption occurred in approximately 12% of patients when using the Comprehensive reverse shoulder arthroplasty, but it has no impact on the functional outcomes or revision rate in the short-to-medium term.