Nonoperative Management of Posterior Shoulder Instability: An Assessment of Survival and Predictors for Conversion to Surgery at 1 to 10 Years After Diagnosis.

Abstract

To (1) define the rate of delayed surgery, between 1 and 10 years after injury, in a population-based study of patients with posterior shoulder instability (PSI), (2) evaluate predictive factors associated with delayed repair, and (3) identify differences between the nonoperative and operative groups at long-term follow-up. A population-based retrospectively reviewed study of all patients with PSI from January 1, 1994, to December 31, 2015, was performed. Inclusion required a clinical diagnosis of PSI combined with supporting imaging. Complete medical records were reviewed for 2,091 potential cases. Kaplan-Meier estimates were used to calculate survival. Landmark survival analysis was performed to identify predictors of conversion to surgery. The study included 143 patients with PSI, 79 of whom were managed nonoperatively for at least 1 year after diagnosis. After the first year, survival free of surgery was 78.3% at 1 year, 63.1% at 5 years, and 51.5% at 10 years. There was a trend toward increased surgery in patients with a body mass index > 35 (P = .10; hazard ratio = 2.32; confidence interval, 0.8-6.8). Nonthrowing athletes (including contact/weight-lifting athletes) showed a trend toward an increased risk for surgery (P = .07). Patients who underwent surgery were significantly more likely to have progression in arthritis (P = .02; hazard ratio = 4.0; confidence interval, 1.2-13.2). Nonoperative management was performed for at least 1 year in over half of patients diagnosed with PSI. Overall, long-term follow-up demonstrates that 46% of these patients converted to surgery between 1 and 10 years after initial diagnosis. Ultimately, 70% of patients diagnosed with PSI go on to surgical intervention. Patients who underwent surgery at any time point were at an increased risk of radiographic progression of arthritis at a minimum of 5 years of follow-up. Level III, cohort study.