Constrained or unconstrained shoulder replacement for musculoskeletal tumor resections?

Many options exist for reconstructing the shoulder after large bony resections of the proximal humerus. One of the more widely used is endoprosthetic replacement. Proximal migration of unconstrained hemiarthroplasty articulations may cause difficulties particularly in the setting of loss of the rotator cuff and/or deltoid musculature. To attempt to overcome these issues, a fixed-fulcrum constrained reverse shoulder replacement option may be considered.

A retrospective review of prospectively collected data from the Queensland Bone and Soft Tissue Sarcoma Service was undertaken to compare the function, implant survivorship, and reoperation rate of constrained reverse and unconstrained hemiarthroplasty-type endoprostheses in patients with tumors.

We retrospectively reviewed data on 41 consecutive proximal or total humeral endoprosthetic replacements undertaken between January 2003 and July 2018. One patient was excluded as lost to follow-up prior to 24 months. There were 21 unconstrained implants and 19 constrained shoulder replacements (Stanmore Modular Endoprosthesis Tumour System with Bayley-Walker articulation). Proximal migration of the unconstrained hemiarthroplasty articulation occurred in 8 patients (38%), and dislocation or failure of the constrained mechanism occurred in 5 (26%). Reoperation for implant-related issues was required in 5 patients in the constrained group and none in the unconstrained group. Of the 18 patients alive at the time of review, 12 provided functional scores. The mean follow-up period for surviving patients was 4.2 years (standard deviation, 2.7 years), with a minimum of 2 years' follow-up. Functional scores were similar between the 2 groups.

Constrained reverse prostheses were associated with a higher reoperation rate in this series without any functional benefit compared with unconstrained hemiarthroplasty-type articulations. We favor the use of unconstrained hemiarthroplasty-type endoprostheses for reconstruction after resection of destructive lesions of the proximal humerus.