The analysis did not identify evidence that the results of TSA were statistically or clinically improved over the 2 decades of study or that any of the individual technologies were associated with significant improvement in patient outcomes.
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Although the indications for anatomic and reverse total shoulder arthroplasty (TSA) are different, better understanding of the rate of improvement with each type of surgery could help establish more realistic patient expectations for recovery—and help surgeons and physical therapists design different strategies for postoperative care. With those goals in mind, Simovitch et al. use prospectively collected data to compare, at a minimum 2-year follow-up, clinical and range-of-motion (ROM) outcomes among 505 anatomic TSA patients and 678 reverse TSA patients. The findings appear in in the November 1, 2017 issue of JBJS.
The authors tracked five clinical outcome scores (SST, UCLA Shoulder, ASES, Constant, and SPADI), along with 4 relevant ROM measures. In both groups, >95% of patients reported clinical improvement in all 5 clinical metrics by 6 months, and full improvement was noted by 24 months. Not surprisingly, the mean age of patients who underwent reverse TSA was >5 years older and their shoulder-function scores and ROM were generally worse than those of the anatomic TSA patients.
At the time of the latest follow-up, patients who underwent anatomic TSA fared significantly better than patients who underwent reverse TSA in 3 of the 5 clinical outcome metrics and in all 4 ROM measurements. On the other hand, those who had reverse TSAs had significantly larger improvements in the Constant score (which emphasizes strength more than the other 4 clinical metrics) and active forward flexion.
ROM-wise, at approximately 6 years after surgery, the authors noted a progressive decrease in the magnitude of improvement for abduction and forward flexion in both groups. According to Simovitch et al., the observed discrepancies between clinical and ROM outcomes at longer-term follow-up suggest that “subjective (e.g., patient-reported) assessments of outcome and function likely continue to be stable or improve despite range-of-motion worsening and, as such, may imply that patient expectations change with follow-up time.”
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