Anatomical and reverse megaprosthesis in proximal humerus reconstructions after oncologic resections: a systematic review and meta-analysis

Aim: Anatomic (AN) Endoprosthesis (EPR) reconstructions of the shoulder after intra-articular proximal humerus (Malawer type 1) resections are characterized by early recovery and low complications rate. However, shoulder instability and limited mobility can occur. Reverse shoulder (RS) EPR has been introduced to improve functional outcome. The aim of this systematic review is to evaluate shoulder reconstructions with AN or RS EPR after Malawer type 1 resection, comparing complications and functional results. Methods: Through an electronic systematic search of PubMed, articles concerning EPR after shoulder Malawer type 1 resections were reviewed. Complications rate, range of motion (ROM) and functional outcome (Musculoskeletal Society Tumor Society—MSTS score) of AN and RS EPR were evaluated. Results: Sixteen studies were included. A similar complication rate was observed between AN and RS EPR rate (26.4% and 22.4%, respectively, p = 0.37). Soft tissue failure was the most frequent complication and cause of revision in both groups. Mean post-operative flexion and abduction ROM and MSTS scores were significantly higher in RS EPR, particularly among patients with preserved deltoid function (p = 0.013, p = 0.025 and p = 0.005, respectively). Conclusions: Anatomic and reverse shoulder EPR represent safe and effective implants for shoulder reconstruction, with similar implant stability and complication rates. RS EPR significantly improves post-operative ROM and functional outcomes, especially when at least a partial function of the abductor apparatus is preserved.