Risk of poor outcomes in patients who are obese following total shoulder arthroplasty and reverse total shoulder arthroplasty: a systematic review and meta-analysis

Background: A systematic review was performed to investigate the impact of obesity on outcomes following total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RTSA). Methods: Electronic databases and the grey literature were searched for studies that evaluated the influence of obesity (body mass index ≥ 30 kg/m²) on TSA and RTSA outcomes. A total of 15 studies were identified, with 10 studies reporting on predetermined outcomes considered in the TSA and RTSA population. Unadjusted data were pooled in a statistical meta-analysis where appropriate (Review Manager [RevMan], version 5.3) or summarized in narrative form. Effect sizes were expressed as odds ratios (ORs) for categorical data and weighted mean differences (WMDs) for continuous data. Results: The findings suggested that patients who were obese were at increased odds of a dislocation (OR, 2.49; 95% confidence interval [CI], 2.32-2.66), fracture (OR, 1.92; 95% CI, 1.77-2.08), and revision (OR, 1.49; 95% CI, 1.40-1.58) following TSA or RTSA. Conversely, obesity had no influence on the odds of an unscheduled return to the operating theater (OR, 0.83; 95% CI, 0.43-1.61). Postoperative forward flexion in patients who were obese differed from that in patients who were not obese (WMD, –9.8°; 95% CI, –17.53° to –2.07°); however, no differences in other functional measures including abduction (WMD, –0.78; 95% CI, –7.27 to 5.71) and external rotation (WMD, –1.41; 95% CI, –5.11 to 2.29) were found. Although patients who were obese reported significantly higher levels of pain (WMD, 1.13; 95% CI, 0.21 to 2.06), the difference was not clinically relevant. Conclusions: Surgeons should consider advising patients who are obese of the greater risk of dislocation, fracture, and revision when considering elective TSA or RTSA. Findings are limited by confounding variables but further our understanding of additional risks associated with pre-existing obesity, which will promote better-informed decisions prior to proceeding with surgery.