Incidence of Associated Injury in Posterior Shoulder Dislocation: Systematic Review of the Literature

Objective: Posterior shoulder dislocations are rare and often missed. Classically associated with seizures, very little is known about the incidence and type of associated injuries. Unfortunately, the majority of the literature consists of incidental reports or small case series. Our goal was to increase the strength of available data by performing a systematic review.

Data Sources: We searched EMBASE and PubMed for the terms "posterior shoulder dislocation." Our inclusion criteria were articles in either English or French with the words "posterior" and "dislocation" in the abstract or title. All reports of chronic cases or instability as well as those without patient information were excluded. Data regarding demographics, etiology, investigations, associated injuries, treatments, and outcomes were extracted. All data were analyzed by using SPSS 18.0 (IBM, Chicago, IL).

Results: A total of 766 articles were found of which 108 were retained for analysis. A total of 475 patients (543 shoulders) were compiled. Seizures were reported in 34% of cases. A majority of dislocations (65%) had associated injuries. Fracture was most common followed by reverse Hill-Sachs and cuff tears. In the absence of fracture or reverse Hill-Sachs injury, the risk of cuff tear increased nearly fivefold (odds ratio, 4.6; P = 0.016).

Conclusion: Our results suggest the amount of associated injuries related to posterior shoulder dislocation is far greater than thought. We propose an investigation algorithm for acute posterior shoulder dislocations.