The natural history of traumatic posterior glenohumeral dislocations in a high-risk population.

Background: The purpose of this study was to define the clinical trajectory and treatment outcomes after traumatic posterior shoulder dislocation in patients treated both operatively and non-operatively. Methods: We queried for all patients ≤50 years old who had a posterior shoulder dislocation or subluxation event, confirmed on imaging between January 2017 and December 2024. Patients were excluded for <6 months of follow-up from the date of the dislocation or subluxation event. Functional failure was defined as persistent subjective instability/pain with a positive Kim/Jerk exam, permanent activity restrictions, or failure to return to work. Additionally, recurrent dislocation, revision surgery, or transition from therapy to surgery was considered structural failure at any time point. Results: Thirty-three shoulders met inclusion criteria. Mechanisms of injury included falls (n = 15, 45%), seizures (n = 7, 21%), combat/military training (n = 7, 21%), sports (n = 2, 6%), and motorcycle accident (n = 2, 6%). The average age at the time of injury was 28.5 years. There were 31/33 (94%) active duty service members and 2/33 (6%) immediate family of service members. Non-operative treatment was undergone in 18/33 patients (55%), and 11/18 patients (61%) failed treatment most commonly due to recurrent dislocations (n = 8, 73%). Operative treatment was undergone in 15/33 patients (45%), and the most common procedure was an arthroscopic posterior labral repair (n = 11, 73%). The average posterior glenoid bone loss in the non-operative group was 11.9% and 12.2% in the operative group. The average gamma angle for the reverse Hill-Sachs lesions in the non-operative group was 97.5° and 83.13° in the operative group. The overall failure rate of operatively managed shoulders was 8/15 shoulders (53%), due to revision surgery in 4/8 patients (50%), redislocation events in 2/8 patients (25%), and subjective instability in 2/8 patients (25%). Seven of 15 (47%) of the operative cohort were placed on permanent profile restrictions or failed to return to duty due to the injured shoulder. Conclusion: Traumatic posterior dislocations in young, active individuals demonstrated high failure rates with both operative (53%) and non-operative (61%) management, though direct comparison between treatment groups is limited by treatment selection bias. Nearly all patients with failure after operative intervention failed to return fully to their occupation.