Shoulder surgery for complex conditions such as irreparably large rotator cuff tears has been revolutionized by the concept of reverse total shoulder arthroplasty (rTSA). Improved design of rTSA implants by multiple manufacturers has resulted in excellent functional outcomes from these procedures. I have been educated by my shoulder colleagues to the fact that primary rTSA is actually technically less demanding than primary anatomic TSA because of greater exposure of the scapula/ glenoid anatomy.
When anatomic TSA clinically and/or radiographically fails, conversion to rTSA is an alternate to revision anatomic TSA. However, the more expensive and complex rTSA system can be difficult to implant in the revision scenario. In the May 3, 2017 issue of The Journal, Crosby et al. provide the outcomes of conversion from primary anatomic TSA to revision rTSA among two groups: those who originally received a convertible-platform implant system, allowing the humeral stem to be retained during revision, and those whose revision required humeral stem exchange.
Patients with retained-stem revisions had significantly shorter operative times, lower estimated blood loss, lower intraoperative complication rates, and slightly better postoperative ROM. Although the authors caution that “the presence of a convertible-platform humeral component does not guarantee that it can be retained,” they conclude that the data from this study “support the use of a convertible-platform humeral stem when performing primary shoulder arthroplasty.”
Whenever possible, it’s a good idea to design implants where the portions that remain well-fixed can be retained and re-used for the rare revision situation. Such retained, modular parts can save resources, reduce operative time and patient morbidity, and may improve functional outcomes. However, we must be aware that issues with wear debris that have surfaced in modular hip components may also come into play with modular shoulder components.
Marc Swiontkowski, MD