Bony increased-offset reverse shoulder arthroplasty: A meta-analysis of the available evidence

Background Reverse shoulder arthroplasty (RSA) has revolutionized the management of many shoulder pathologies. Lateralization has become favourable to combat complications (e.g. notching, compromised external rotation), using a metallic, or autogenous bone-graft baseplates – bony increased-offset reverse shoulder arthroplasty (BIO-RSA). We systematically reviewed the literature to determine: Does BIO-RSA improve range of motion and outcome scores? Are notching rates decreased? Does the graft heal? Methods All available prospective studies, trials and case series reporting on BIO-RSA were included. Outcomes were grouped into outcome scores, range of motion and radiographic outcomes. Data were pooled and statistical analysis performed. Results Eight studies reported on 385 RSA – 235 BIO-RSA and 150 standard-RSA (STD-RSA). Follow-up was 20–36 months; average age 74 years. Outcome scores: Constant-Murley and SSV scores showed statistically significant post-operative benefit of BIO-RSA (mean-difference 4.0 (95% confidence interval (CI): 0.79,7.1) and 6.8 (95% CI: 3.8, 9.9)). No Minimal Clinically Importance Difference was surpassed. Range of motion: No difference was found in any direction. Notching: Notching was less likely with BIO-RSA (odds ratio 0.19 (95% CI: 0.10, 0.38)). Healing and loosening: 92% grafts fully healed/incorporated. Loosening rate was 2.4%. Conclusions Literature on BIO-RSA is limited with only one randomised controlled trial (RCT). Weak evidence exists for improved outcome scores. Range of motion is equivocal. Notching rates are significantly lower in BIO-RSA. The graft usually heals.