Medialized vs. Lateralized Reverse Total Shoulder Arthroplasty for Proximal Humerus Fractures: A Systematic Review and Meta-Analysis.

Background: Reverse shoulder arthroplasty (RSA) is increasingly used in the treatment of proximal humerus fractures (PHFs) with reliable clinical improvement. Lateralized RSA implants have conferred superior outcomes compared with the original Grammont design in patients with nontraumatic indications. However, in the setting of a PHF, lateralized components can place increased tension across the tuberosity fracture site and potentially compromise tuberosity healing and outcomes. This systematic review and meta-analysis sought to determine the effect of implant design on clinical outcomes after RSA for PHFs.

Methods: A systematic review was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane were queried for clinical studies on RSA performed for PHFs that reported implant manufacturer details. Our primary outcomes included postoperative external rotation (ER), forward elevation (FE), abduction, Constant score, rate of greater tuberosity (GT) healing, and the incidence of complications compared between medialized vs. lateralized global implant design.

Results: Globally lateralized RSA cohorts (478 RSAs total with cumulative lateral offset achieved through humeral or glenoid lateralization or both humeral and glenoid lateralization) were found to have a greater mean postoperative Constant score compared with globally medialized (medialized glenoid and medialized humerus) RSA cohorts with 1,494 total medialized RSAs (66 vs. 59, p = 0.006), but there was no significant difference regarding mean postoperative ER (30° vs. 22°, p = 0.078), FE (117° vs. 119°, p = 0.708), or abduction (103° vs. 107°, p = 0.377). On meta-regression, neither implant design nor tuberosity status significantly influenced postoperative ER, FE, abduction, or Constant score on meta-regression independent of mean follow-up and age at surgery. The rate of GT healing was greater in lateralized compared with medialized RSAs (88% vs. 72%, p < 0.001). On meta-regression, medialized RSA design was associated with a 73% lower odds of GT healing (odds ratio = 0.27, 95% confidence interval = 0.11-0.68, p = 0.007) independent of mean follow-up and age at surgery.

Conclusion: Lateralized RSA implants conferred no significant functional benefit over medialized implants when used in patients with PHFs.

Level of evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.