Stemless anatomic and reverse shoulder arthroplasty in patients under 55 years of age with primary glenohumeral osteoarthritis: an analysis of the Australian Orthopedic Association National Joint Replacement Registry at 5 years.

Background: Primary glenohumeral osteoarthritis in young patients poses challenging treatment decisions. Arthroplasty options have different failure profiles and implant survivorship patterns. This registry study aims to analyze the cumulative per cent revision (CPR) rate of different types of arthroplasties conducted for primary osteoarthritis in patients below 55 years of age.

Methods: This comparative observational national registry study included all shoulder arthroplasty for osteoarthritis in patients below 55 years of age undertaken between January 1st, 2005, and December 31st, 2022. Partial hemi resurfacing and hemi stemless procedures were excluded. The CPR was determined using Kaplan-Meier estimates of survivorship and hazard ratios (HRs) from Cox proportional hazard models adjusted for gender. Reasons for revision of each type of arthroplasty and cumulative incidence of revision diagnoses were analyzed.

Results: Two thousand one-hundred eleven primary shoulder arthroplasties were compared. Glenoid erosion is the predominant cause of revision for humeral resurfacing (29.8%) and hemiarthroplasty (35.5%). Instability is the predominant cause of revision for stemmed anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA), while loosening is the predominant cause of revision for stemless aTSA. The 6-year CPR is 12.8% for humeral resurfacing, 14.1% for hemiarthroplasty, 12.4% for stemmed (aTSA), 7.0% for stemless aTSA, and 6.5% for rTSA. Stemmed aTSA had a higher revision rate than rTSA (entire period HR = 2.04 (95% confidence interval 1.16, 3.57), P = .012). In contrast, the revision rate of stemless aTSA was not different from rTSA (HR = 1.05 (95% confidence interval 0.51, 2.19), P = .889). Males outnumber females for all shoulder arthroplasty categories.

Discussion: rTSA and stemless aTSA are viable options in young patients with primary osteoarthritis. Their short-to-medium term revision rates are comparable to those of older patients and lower than those associated with humeral resurfacing, hemiarthroplasty, and stemmed aTSA.

Conclusion: In the predominantly male patient population below the age of 55, reverse shoulder arthroplasty and stemless aTSA have a lower short-term revision risk than stemmed aTSA.