Reverse Shoulder Arthroplasty Megaprosthesis for Surgical Management of Severe Proximal Humeral Bone Loss.

INTRODUCTION: Shoulder arthroplasty in the setting of severe proximal humerus bone loss can be challenging. The purpose of this study was to evaluate the outcomes of a modular segmental megaprosthesis when implanted in a reverse configuration for complex primary arthroplasty, reconstruction at the time of oncologic resection, and revision shoulder arthroplasty.

MATERIALS AND METHODS: A Joint Registry Database was queried to identify all shoulder arthroplasties performed at a single institution using the Comprehensive Segmental Revision System® reverse shoulder arthroplasty (SRS-RSA, Zimmer Biomet, Warsaw, IN, USA). A retrospective review of electronic medical records and radiographs was performed to record demographic data, indication, outcomes, complications, and revision surgery.

RESULTS: Between February 2012 and October 2022, 76 consecutive SRS-RSA were implanted. An analysis of patients with minimum 12-month follow-up yielded 53 patients with a mean follow-up of 4.1 ± 2.43 years. Surgical complication rate in this cohort was observed in 41.5% (22/53) of cases. Overall, revision rate at final follow-up was 26.4% (14/53), with a significant difference between the primary and revision cohorts. The number of prior surgeries was a significant risk factor for revision surgery, with a hazard ratio of 1.789 (p<.001 95%CI [1.314-2.436]). When analyzing aseptic humeral loosening rates across study cohorts, a significant difference was found between the primary arthroplasty (0%, n = 0) and the revision arthroplasty cohorts (22.2%, n = 6) (p = 0.04).

DISCUSSION: Reverse shoulder arthroplasty using a modular segmental megaprosthesis remains a reasonable salvage option for shoulder reconstruction in the setting of proximal humeral bone loss. Due to the substantial bone loss and soft tissue deficiencies typically present in these cases, surgeons should educate patients on the relatively high complication rate, particularly when used in the setting of a previous failed arthroplasty.