Anterior subluxation and dislocation accounted for more than half of shoulder instability injuries in contact collegiate athletes; additionally, surgery rates and time lost to instability injuries varied significantly between Divisions I, II, and III.
Contact athletes have the highest shoulder instability rates among all collegiate athletes, however, no previous studies have evaluated the types, mechanisms, or severities of such injuries in this population. Also, outcomes have not been compared between Divisions I-III. The purpose of this study was to evaluate the epidemiology of shoulder instability injuries in contact collegiate athletes and compare outcomes at different levels of competition.
Data was obtained from the Datalys Center for Sports Injury Research and Prevention, Inc. Reportable injuries resulted from participation in an organized team practice or competition and required attention from an athletic trainer or physician. An athlete-exposure (AE) was one student-athlete participating in one NCAA-sanctioned practice or competition, regardless of the time associated with that participation. Incidence rates (IR) per 100,000 AEs were calculated with 95% confidence intervals (CI). Injury proportion ratios (IPR) were calculated to compare competition and practice injury rates. Analysis of variance was used to compare time lost (TL) and chi-square was utilized to compare surgery rates between divisions.
Overall, 445 shoulder instability injuries (categorized as subluxation, dislocation, and strain) occurred in 1,421,561 AEs from 2009/10 to 2013/14 (IR, 31.30; 95% CI, 28.4-34.21). Instability occurred significantly more often during competition than practice (IPR, 4.43; 95% CI, 3.66-5.35). Wrestling (IR, 35.56) and football (IR, 35.14) were the most likely to sustain an injury. Subluxation accounted for 59.1% of all injuries, followed by strain (23.4%), and dislocation (17.5%). Anterior subluxation (35.3%) was the most common injury type. Player contact was the most common mechanism for all injury categories (i.e. subluxation, dislocation, strain) and sports. The mean practice and competition TL for all instability injuries was 8.17 days. Shoulder dislocation had the longest average TL (17.58 days). Division I athletes had mean TL of 4.77 days, Division II had mean 20.52 days TL, and Division III missed an average of 11.23 days (p=0.01). For 39 of the 445 injuries, it was unclear if the athlete underwent surgery. Of the 406 remaining injuries, 119 (29.3%) required surgery. Hill-Sachs lesions were most likely to result in surgery (2/3, 66.7%), followed by Non-SLAP glenoid labrum tears (33/53, 62.3%). Division I (79/240, 32.9%), Division II (16/42, 38.1%), and Division III (24/124, 19.4%) surgery rates also differed significantly (p=0.04).
Wrestling and football were the most likely collegiate contact sports to sustain a shoulder instability injury. Anterior subluxation and dislocation accounted for 52.1% of all shoulder instability injuries. Player contact was the most common mechanism of injury. On average, injured athletes missed more than week, and nearly 30% of injuries required surgery. Surgery rates and TL were significantly different between divisions, which may be due to differential funding and medical coverage.