Short-term radiographic and clinical outcomes of patients treated with anatomic total shoulder arthroplasty using a modern-generation implant with a metal-backed glenoid component

Abstract

BackgroundA leading cause of anatomic total shoulder arthroplasty failure continues to be glenoid component loosening. Historically, metal-backed glenoids (MBG) have shown decreased performance compared to polyethylene-backed glenoid (PEG) components. Previous studies have shown that MBG components have higher revision rates and shorter time to prosthetic failure compared with PEG components. However, the negative outcomes of many of these studies may have been linked to an examination of older generations of MBG implants, and do not account for newer technology. Thus, our study aims to assess the short-term radiographic and clinical outcomes of patients treated with anatomic total shoulder arthroplasty using the current and more modern generation of implants with a universal metal-backed glenoid component. MethodsWe conducted a retrospective chart review of patients who had their primary anatomic shoulder replacement performed from 2017 to 2022 by a single surgeon, and used one of two currently available implants that incorporated a metal-backed glenoid component with a convertible baseplate. After the exclusion of those lost to follow-up, we included 26 patients in this study, 3 of whom underwent bilateral shoulder replacement surgery at staggered time intervals. The primary outcome measure was evidence of radiographic change via in-office X-ray. Analysis of radiographic changes was conducted for each postoperative visit, which was aimed for 2 weeks, 6 weeks, 12 weeks, 1 year, and annually thereafter. Secondary analysis tracked clinical progression and utilized DASH scores, range of motion evaluation, strength testing, and instability examination using evidence of apprehension and sulcus signs at each time interval. ResultsIn our study, radiographic changes at each time interval and the longest follow-up appointment demonstrated no evidence of hardware loosening of either the glenoid or the humeral component and no evidence of periprosthetic fracture or hardware failure of any kind for MBG implants. There were no revisions performed due to polyethylene wear. The overall average range of motion, strength, and DASH scores were improved at each postoperative visit. ConclusionPrevious studies have suggested that TSA implants with MBG components may be inferior to PEG implants. However, the results of many of these studies may not be as representative of the current implant designs available today. While additional studies are necessary to assess the long-term survivability of the implant and its effects on glenoid bone stock, our findings suggest that university MBG components have minimal complications, do not demonstrate loosening, and have acceptable outcomes in short-term follow-up.