Posterior Shoulder Dislocation Has Low Prevalence
Recurrent instability predicted by age, dislocation during seizure, large reverse Hill-Sachs lesion
MONDAY, Sept. 19 (HealthDay News) -- Prevalence of posterior dislocation is low, with recurrent instability the most common complication after injury, and functional deficit persisting at two years after injury, according to a study published in the Sept. 7 issue of The Journal of Bone & Joint Surgery.
C. Michael Robinson, B.Med.Sci., from the New Royal Infirmary of Edinburgh in the United Kingdom, and colleagues investigated the epidemiology, demographics, post-treatment functional outcome, and recurrence risk of acute traumatic posterior dislocation of the shoulder in 112 patients with 120 posterior glenohumeral dislocations. Functional outcome was assessed during two years post-dislocation using the Western Ontario Shoulder Instability Index (WOSI) and the limb-specific Disabilities of the Arm, Shoulder, and Hand score (DASH).
The investigators found that posterior dislocation had a prevalence of 1.1 per 100,000 people per year. This peaked in male patients aged between 20 and 49 years and in patients aged over 70 years. Traumatic accidents caused 67 percent of the dislocations, and seizures caused most of the remaining studied dislocations. Recurrent instability was identified in 23 shoulders, with survival analysis identifying recurrent instability in 17.7 percent of the shoulders within the first year. Recurrent instability was predicted by an age of younger than 40 years, dislocation during a seizure, and a large reverse Hill-Sachs lesion (>1.5 cm³). The WOSI and DASH detected small persistent functional deficits at two years.
"The prevalence of posterior dislocation is low. The most common complication after this injury is recurrent instability," the authors write.