Gender differences in anterior cruciate ligament injury vary with activity - Epidemiology of anterior cruciate ligament injuries in a young, athletic population

[Background: Previous studies have shown that women involved in similar activities as men are at increased risk for anterior cruciate ligament injuries. Hypothesis: The incidence rate of complete anterior cruciate ligament tears for men and women in our athletic, college-aged population is similar. Study Design: Descriptive epidemiology study. Methods: Students graduating in class years 1994 to 2003 at our institution who sustained complete anterior cruciate ligament tears were assessed for mechanism of injury and type of sport played at time of injury. We calculated the incidence proportion, an estimation of risk, by gender and class year, and the incidence proportion ratio comparing men and women by class year. We also calculated incidence rates by gender and type of sport played and incidence rate ratios comparing men and women. Results: There were 353 anterior cruciate ligament injuries in the 10 classes studied. We found an overall, 4-year incidence proportion of 3.24 per 100 (95% confidence interval, 2.89-3.63) for men and 3.51 (95% confidence interval, 2.65-4.65) for women (incidence proportion ratio, 1.09 [95% confidence interval, 0.80-1.47]). The overall anterior cruciate ligament injury rate, excluding male-only sports, was significantly greater in women (incidence rate ratio, 1.51 [95% confidence interval, 1.03-2.21]). We found significantly greater injury rates among women in a gymnastics course (incidence rate ratio, 5.67 [95% confidence interval, 1.99-16.16]), indoor obstacle course test (incidence rate ratio, 3.72 [95% confidence interval, 1.25-11.10]), and basketball (incidence rate ratio, 2.42 [95% confidence interval, 1.05-5.59)). Conclusion: We found little gender difference in the overall risk of an anterior cruciate ligament tear; however, there were gender differences in injury rates when specific sports and activities were compared and when male-only sports were removed from the overall rate assessment.