Staged reverse shoulder arthroplasty with structural allograft-prosthesis composite and lower trapezius tendon transfer for massive proximal humeral bone loss following gunshot injury: a case report.

Massive proximal humeral bone loss with concomitant rotator cuff deficiency is a rare and complex reconstructive challenge, particularly after high-energy trauma. Reverse shoulder arthroplasty (RSA) with an allograft-prosthesis composite (APC) restores humeral length and soft-tissue attachment, while tendon transfer addresses residual rotational deficits. We report a 35-year-old male who presented two weeks after a gunshot injury with an 8-cm open wound and extensive proximal humeral bone loss. Following serial debridement and culture-directed antibiotics, staged reconstruction was undertaken. Initial stabilization with intramedullary nailing and a cement spacer was followed by definitive RSA-APC 21 months post-injury. A structural proximal humeral allograft was fixed with an anterolateral plate, and a lower trapezius tendon transfer was performed using the allograft's native soft-tissue attachment as a biologic anchor. At 2-year follow-up, complete graft incorporation was observed with meaningful functional improvement.