Constrained or unconstrained shoulder replacement for musculoskeletal tumor resections?

Area of Science:

• Orthopedic Surgery
• Oncology
• Biomedical Engineering

Background:

• Shoulder reconstruction after proximal humerus resection often involves endoprosthetic replacement.
• Unconstrained hemiarthroplasty can face challenges like proximal migration, especially with rotator cuff or deltoid loss.
• Fixed-fulcrum constrained reverse shoulder replacement is an alternative to address these challenges.

Purpose of the Study:

• To compare functional outcomes, implant survivorship, and reoperation rates.
• To evaluate constrained reverse versus unconstrained hemiarthroplasty endoprostheses.
• To assess effectiveness in patients undergoing tumor resection of the proximal humerus.

Main Methods:

• Retrospective review of prospectively collected data.
• Analysis of 41 proximal or total humeral endoprosthetic replacements (21 unconstrained, 19 constrained).
• Comparison of implant-related issues, reoperation rates, and functional scores.

Main Results:

• Proximal migration occurred in 38% of unconstrained implants; dislocation/failure in 26% of constrained implants.
• Reoperation was required in 5 constrained cases, none in unconstrained cases.
• Functional scores were similar between the two groups, with a mean follow-up of 4.2 years.

Conclusions:

• Constrained reverse prostheses demonstrated a higher reoperation rate without functional advantage over unconstrained hemiarthroplasty.
• Unconstrained hemiarthroplasty-type endoprostheses are favored for reconstruction after proximal humerus tumor resections.
• This suggests unconstrained implants may offer a safer option for these complex reconstructions.