A Prospective Study on the Effect of Sport Specialization on Lower-Extremity Injury Rates in High School Athletes

SLR - December 2017 - Jason N. Birkel

Scientific Literature Review

Reviewed By: Jason N. Birkel, DPM
Residency Program: UPMC Pinnacle Health, Harrisburg, PA

Podiatric Relevance: Sports medicine is a major part of the podiatric practice. Lower-extremity injuries (LEIs) account for 60 to 75 percent of high school sports injuries, many of which require surgical correction. This study shows that athletes with higher specialization are at an increased risk for LEI. It is the responsibility of the podiatric surgeon to educate patients and parents of the risks associated with increasing specialization (focusing on a single sport), as well as being proactive with treating overuse injuries.

Methods: This is a level 2 cohort study. Data was collected from 29 Wisconsin high schools during the 2015–2016 academic year. All schools needed to have a certified athletic trainer to participate. Students participating in interscholastic sports were eligible to fill out a preseason questionnaire identifying the level of student specialization as low, moderate or high based on months spent on the primary sport as well as priority placed upon that sport by the student. Questionnaires also identified history of LEI. Parents were encouraged to assist students, and each completed form was reviewed by members of the research team to ensure accuracy in reporting. Athletic trainers were responsible for injury reporting. Statistical analysis utilized odds ratios and multivariate Cox hazard ratios with 95 percent confidence intervals. Multivariate analysis was used to correct for and analyze influencing factors, including primary sport, history of injuries, grade and sex. All analysis was performed using R statistical software.

Results: 1,544 participants enrolled in this study, encompassing 2,843 athletic seasons and 167,349 athletic exposures (“coach-directed conditioning session, practice or competition”). 50.5 percent of participants were female, mean age was 16.1 with a standard deviation of 1.1 years. Fifty-nine percent of students met criteria for low level of sport specialization, while 27.2 percent were moderate and 13.3 percent were high. 15.2 percent of athletes sustained LEI with no difference between sexes in sex equivalent sports, such as baseball/softball, basketball, soccer and tennis. Ankle injuries were most common at 34.4 percent of LEI, and 8.3 percent of injuries required surgical treatment. Athletes in the moderate category (P = .03) had a 50 percent higher incidence of LEI than the low group. Athletes in the high category (P = .02) had an 85 percent higher incidence of LEI than the low group. This was consistent with nonacute injuries as well. There appeared to be no statistically significant difference between the three groups when looking at acute injuries, and higher levels of athletic volume did not show a statistically significant increase in LEI either.

Conclusion: Based on the findings in this study, the authors concluded that higher sports specialization was found to be an independent risk factor for LEI, with athletes who specialized in fewer sports being at an increased risk for LEI, specifically nonacute (overuse) injuries. No increased risk was associated with sex or overall participation volume or time. Physicians with patients who specialize in fewer sports can educate parents and coaching staff regarding the increased risk of LEI. Additional education for the involved parties in overuse injury prevention and treatment may be warranted.