Male gender and age range 20-29 years are the most important non-modifiable risk factors for recurrence after primary post-traumatic shoulder dislocation.

PURPOSE: The aim of the study was to identify and analyze non-modifiable risk factors for recurrence after a first-time post-traumatic dislocation of the shoulder in the entire Polish population.

METHODS: The entire Polish population was included in a cohort study. Patients diagnosed with primary post-traumatic dislocation of the shoulder between January 1st, 2010 and December 31st, 2011 were identified and followed up from January 1st, 2010 to December 31st, 2014. Incidence and recurrence rates and odds ratios (OR) were calculated. Demographic data were obtained from Poland's Central Statistical Office. Data on the number of patients with primary post-traumatic shoulder dislocation were drawn from the National Health Fund database.

RESULTS: A total of 21,739 patients (14,466 males and 7273 females) with a primary shoulder dislocation in Poland were identified in 2010 and 2011. There were 3341 (15.4%) recurrences. Increased risk of recurrence was associated with male gender (OR = 1.92, 95% CI 1.76-2.09, p < 10-10 ) in the age range of 20-29 years (OR = 2.59, 95% CI 2.38-2.83, p < 10-10 ). The highest risk of first-time shoulder dislocation was revealed among females in the age group ≥ 80 years (OR = 24.1, 95% CI 22.6-25.7, p < 10-10 ). The risk of recurrence in the same group was significantly decreased (OR = 0.41, 95% CI 0.32-0.51, p < 10-10 ).

CONCLUSION: Male gender and age range 20-29 years are highest population risk factors for recurrence after primary shoulder dislocation. Female gender and age ≥ 80 years are highest risk factors for the first-time post-traumatic dislocation of the shoulder joint and protective factors for recurrences after the first-time shoulder dislocation.

LEVEL OF EVIDENCE: III.