Abstract
Introduction: Globally, the prevalence of total shoulder arthroplasty, both anatomic (aTSA) and reverse (rTSA) have markedly increased. This growth coincides with significant growth in the rate of obesity. Despite evidence correlating obesity with inferior outcomes in patients receiving lower limb arthroplasty, the effect of obesity on shoulder arthroplasty remains unclear. The objective of this study was to evaluate the correlation of obesity with total shoulder arthroplasty outcomes using data from the New Zealand Joint Registry (NZJR).
Methods: This study utilized data collected from the NZJR for patients undergoing primary aTSA and rTSA between January 1, 2011 and December 31, 2022 who had BMI data recorded. 5,628 shoulders were included in the study, including 1,696 aTSAs and 3,932 rTSAs. The primary outcome measure was all-cause revision rate (rate/100 component years) stratified by BMI class. Secondary outcome measures included the Oxford Shoulder Score (OSS).
Results: The overall risk of revision for all shoulders was 1.01 for aTSA (95% CI 0.79-1.26) and 0.70 for rTSA (95% CI 0.57-0.86). The risk of all-cause revision did not increase with increasing BMI class in either the aTSA or rTSA group. Amongst those who had aTSA, those with class II/III obesity had the lowest revision rate of 0.77 (95% CI 0.39-1.28). Amongst those who had rTSA, risk of revision remained low amongst all BMI groups with class II/III obese patients showing a non-significant trend towards higher risk of revision (adjusted HR 1.61 (95% CI 0.81-3.23)). There was no association between elevated BMI and risk for deep infection. There was no association between OSS and BMI.
Conclusion: The results from the NZJR support the continued use of anatomic total shoulder arthroplasty and reverse shoulder arthroplasty in the obese population. Obesity was not found to be an independent risk factor for adverse outcomes in shoulder arthroplasty in our study.