Beware: Relatively high revision rates of TSA after anterior instability procedures.

Referenced article: Vopat et al… “Outcomes of total shoulder arthroplasty in patients with prior anterior shoulder instability: minimum 5-year follow-up”

While it is known that there is a risk of arthritis after anterior shoulder instability, termed instability arthropathy, there are relatively few articles on the outcomes of shoulder arthroplasty after anterior instability.

This article reported on 36 patients undergoing total shoulder arthroplasty (TSA) with prior anterior shoulder instability who had good results from the surgery. They compared patients who had prior operative management to patients who were treated nonoperatively for their shoulder instability with minimum 5-year follow-up.  In the prior surgery group, they also compared arthroscopic and open procedures as well the number of procedures to see if it affected the postoperative outcomes.

Interestingly, nonoperatively treated patients with shoulder instability had similar postoperative outcomes compared to the patients with prior anterior instability procedures regarding the ASES score, SANE, QuickDASH, and SF-12 scores in the patients not undergoing revision. However, TSA failure was much higher in the operative cohort [6 of 21 patients (29%) versus 0 of 15 in the nonoperative group].  Of these 6 failures, two had cuff failure, 2 had infections, one had instability with an intact cuff, and one had glenoid loosening.  While the outcomes between the groups were similar for patients not undergoing revision, this high failure rate is concerning in TSA patients with prior anterior instability surgery.  A similar finding was noted in Patel et al¹ where the revision rate of TSA after prior anterior stabilization procedures was 20% in 15 patients compared to 0% in RTSA in 10 patients. Better improvement in the ASES score as well was noted in RTSA patients. Four older studies also reported relatively high  revision rates between 11-20% with TSA and hemiarthroplasties in patients with prior anterior instability.^2-5

Surgeons and patients need to be aware of this relatively high revision rate after TSA in patients with prior anterior stabilization surgeries.  This data is valuable for surgeons to educate patients on the risks of shoulder arthroplasty after prior anterior shoulder instability and, as opposed to patients with prior anterior stabilization procedures, that good outcomes and low revision rates at minimum 5-years follow-up can be achieved in patients that did not have prior surgery.

Other interesting findings of this study were that the type of surgical procedure (open versus arthroscopic) did not affect the ultimate outcomes in the operative group, however the numbers in each group were small (7 versus 6 patients).  There was no difference in implant survivorship compared to the type of prior surgical procedure. Additionally, the number of prior surgical procedures (1 versus >1) did not affect the ultimate outcomes in the operative group, but the numbers in each group were small with a small mean benefit slightly favoring the patients with only 1 surgical procedure.

The information from this study improves on the information available to surgeons and patients on the outcomes of TSA after anterior shoulder instability.  In my experience, I will continue to be wary of anatomic shoulder arthroplasty in patients with prior anterior instability surgery, but I think shared decision making is important for these patients.  Furthermore, this study highlights the very good results of TSA in patients with nonoperatively treated anterior instability.