Reconstruction by allograft-prosthetic composite reverse shoulder arthroplasty after proximal humerus tumor resection: Clinical and radiographic assessment at a minimum 2years' follow-up

Introduction: Reverse shoulder arthroplasty (RSA) is an option to conserve limb function after resection of proximal humerus malignancy. An allograft-composite RSA is an alternative to a tumor prosthesis, and can restore proximal humeral bone stock. The aim of the present study was to assess medium-term radiographic and clinical results for such composite implants. Methods: Patients with malignant proximal humerus tumor treated by resection and reconstruction by composite RSA were retrospectively analyzed at a minimum 24 months’ follow-up. Clinical assessment used Constant score, Subjective Shoulder Value (SSV) and ADLER score. Standard radiographic work-up assessed allograft absorption and screened for implant loosening. Results: Eleven patients were included, with a mean age of 51 years (range, 19-87 years) and mean 30 months’ follow-up (range, 24-84 months). Mean tumor resection was 10 cm (range, 6-17 cm). Etiologies comprised chondrosarcoma (n=6), osteosarcoma (n=2), B-cell lymphoma (n=1) and single metastasis (n=2). Bony increased-offset allograft was associated to humerus reconstruction in 8 cases, and latissimus dorsi tendon transfer in 5 cases. Mean Constant score was 49 points, SSV 52%, and ADLER score 20 points. Increased glenoid implant offset associated to tendon transfer significantly improved anterior elevation and external rotation. Radiographic allograft consolidation to the native humerus was acquired in 73% of cases, while osteolysis in the epiphyseal-metaphyseal zone was found in 64%. There were no cases of humeral implant loosening. Glenoid allograft absorption was systematic (8/8 cases), without inducing loosening of the implant baseplate. Conclusion: Composite reverse shoulder arthroplasty is functionally effective after massive resection. However, allograft absorption is a drawback, casting doubt on continued use on the glenoid side. Level of evidence: IV.