Recurrence after soft-tissue anterior shoulder stabilization: 2-year results from the MOON shoulder cohort

The purpose of this study was to analyze rates of recurrent shoulder instability and subsequent surgery, as well as the risk factors associated with those outcomes, in a large prospective multicenter cohort of patients.

Patients undergoing surgery for traumatic or atraumatic anterior shoulder instability were prospectively enrolled. The outcomes of interest were subsequent shoulder dislocation, subluxation, or repeat surgery. Multivariate analyses were performed to specifically analyze patient and surgical factors associated with recurrent instability.

Of the 1,040 enrolled patients, 889 (85.5%) had 2-year follow-up data. At 2-year follow-up, 43 patients (4.8%) had undergone subsequent surgery for instability, 77 (8.7%) had a shoulder dislocation and 221 (24.9%) reported a shoulder subluxation. Multivariate analysis demonstrated that younger age (P = .006), a higher Personality Assessment Screener 22 (PAS-22) score (P = .02) and number of preoperative dislocation events (P = .015) were associated with having recurrent instability, whereas smoking approached significance (P = .055). Subanalysis of the 778 primary arthroscopic stabilization patients demonstrated that 46 patients (5.9%) suffered a dislocation within 2 years after surgery. Younger age (P = .0005), smoking (P = .015), higher PAS-22 score (P = .049), and the number of preoperative dislocations (P = .020) were patient factors associated with recurrent dislocation. None of the surgical variables, including beach chair vs. lateral positioning, and the number or type of anchor used were significant. Revision surgery (P < .001), duration of preoperative symptoms (P = .046), and a higher PAS-22 score (P = .34) were associated with a subjective report of shoulder subluxation.

In a very large prospective multicenter cohort, with more than 85% follow-up, approximately one-third of patients had experienced repeat surgery, recurrent dislocation, or reported a subluxation or slipping event. Younger age was the strongest risk factor for recurrence after surgery. Smoking, mental health, and number of preoperative dislocations were identified to increase risk for recurrence in the first 2 years. None of the surgical variables analyzed, including beach chair vs. lateral positioning, were significant. These data can be used to guide surgeons and counsel patients who are undergoing anterior shoulder stabilization surgery.