The True Recurrence Rate and Factors Predicting Recurrent Instability After Nonsurgical Management of Traumatic Primary Anterior Shoulder Dislocation: A Systematic Review

Abstract

Purpose: To (1) define the cumulative recurrence rate after primary anterior shoulder dislocation in Level I and II comparative studies and (2) to pool risk ratios for common risk factors to provide a clinically practical hierarchy of modifiable and nonmodifiable risk factors for recurrence.

Methods: Level I and II prognostic studies were identified using the electronic databases CINAHL, Embase, and MEDLINE from inception to December 2014. Included studies (n = 15) had recurrent dislocation as the main outcome, and a minimum 2-year follow-up. The cumulative odds ratio of prognostic factors was calculated where appropriate. Bias was assessed in each study using the Quality in Prognosis Studies (QUIPS) tool.

Results: The reported rate of recurrence ranged from 19% to 88% (pooled overall = 21%; pooled Level I only = 47%). The pooled time to recurrence was 10.8 months (standard deviation 0.42). Male sex (n = 6 studies) conferred a 2.68 (1.66-4.31; P < .001) and patient age <20 years (n = 4 studies) conferred a 12.76 (5.77-28.2; P < .001; vs >20 years) increased odds of recurrence. An associated greater tuberosity fracture (n = 7 studies) decreased the odds of recurrence by 3.8 times (2.94-5.00; P < .001). The quality of evidence was moderate for age, low for sex, and very low for all other prognostic variables.

Conclusions: The pooled rate of recurrence after primary anterior shoulder instability was found to be 21% among moderate- to high-quality prognostic studies. Male sex and younger age predicted a significantly higher risk of recurrent instability (approaching 80%), whereas concurrent fracture of the greater tuberosity significantly decreased the risk of subsequent recurrent dislocation. However, considering the quality of available evidence for these predictors, there remains a clear need for further high-quality prospective studies.

Level of evidence: Level II, systematic review of Level I and II prognostic studies.