Incidence of recurrence after shoulder dislocation: a nationwide database study

Background: The reported incidence of shoulder redislocation varies among different reports. This was a nationwide study to investigate the recurrence rate of shoulder dislocation after closed reduction. Methods: We performed a cohort study to analyze the incidence of first dislocation as well as second and third repeated dislocations in a nationwide dataset from the National Health Insurance Research Database of Taiwan. Patients who had any shoulder dislocation event and received closed reduction from 2000 to 2013 were included. Results: From this dataset of 1 million persons, we identified 1074 patients who had a shoulder dislocation. Of these, 210 had a second shoulder dislocation and 93 had a third shoulder dislocation. The shoulder redislocation rates were 9.4%, 12.7%, and 17.0% at 1 year, 2 years, and 5 years, respectively, after the first shoulder dislocation and 19.6% at overall follow-up. Patients in the youngest age group and male patients had higher risks of redislocation (adjusted hazard ratios, 3.28 and 1.41, respectively). The mean time to recurrence was 13.1 months. However, the patients who had a second shoulder dislocation had a shorter time to recurrence and a higher risk of redislocation (44%), with no statistical differences in risk among any age or sex groups. Conclusions: After the first shoulder dislocation, male patients and younger patients had higher shoulder redislocation rates. However, after the second shoulder dislocation, all groups shared a similar high shoulder redislocation rate regardless of age or sex. Surgical treatment should be considered for patients with multiple episodes of shoulder dislocation.