Recent advances in shoulder arthroplasty

Abstract

Prosthetic shoulder arthroplasty is becoming increasingly popular. The most widely reported procedures are hemiarthroplasty and unconstrained total arthroplasty using the Neer II prosthesis, which involves insertion of a press-fit or cemented humeral component and a cemented polyethylene glenoid implant. Long-term studies show that excellent or good results are achieved in over 90% of cases, with 87% probability of implant survival at 15 years. Metal backing of cemented glenoid components has yielded disappointing results. In total shoulder arthroplasty, the use of cement on the humeral side is recommended but, in hemiarthroplasty, press-fit fixation remains acceptable. The current indications for hemiarthroplasty are: normal glenoid surface, traumatic four part fracture dislocation of the shoulder joint, massive cuff tear arthropathy and severely eroded glenoid process. Total shoulder arthroplasty appears to achieve superior and more predictable results in rheumatoid patients. In osteoarthritis, the choice between hemi-and total shoulder arthroplasty remains controversial. In juvenile rheumatoid arthritis, both procedures appear to be equally effective. Fully constrained/fixed fulcrum devices have been the focus of much adverse publicity. However, they may still have a role to play in the treatment of severe cuff tear arthropathy or revision surgery for persistent prosthetic instability. Recent years have witnessed the introduction of numerous uncemented prostheses. Early results are encouraging but long-term follow-up studies are lacking. Other recent innovations include complex modular systems, bioactive implant surfaces, variable humeral head alignment, non-conforming articular surfaces and surface arthroplasty. Their superiority over the more traditional and tested Neer II system with fully conforming articulating surfaces remains unproven. Until further evidence becomes available, the cemented Neer II prosthesis with an all polyethylene glenoid component should be considered as the gold standard.