The Effect of Previous Hamstring Injuries on ACL Injury Risk

Abstract

There are between 100,000 and 200,00 ACL injuries a year with 60% of the injuries being noncontact related. The hamstring muscles increase knee stability and decrease stress on the ACL by assisting in preventing anterior tibial translation. If the hamstring muscles are comprised, they are not able to reduce the load on the ACL, putting excess strain on the ligament. The purpose of this study was to determine if athletes with a prior hamstring injury are at a relative higher risk of ACL injury compared to athletes without hamstring injury. This retrospective study evaluated 274 unique players over 5.5-year period. The number of athletes with hamstring injuries, with ACL injury, and with both ACL and hamstring injuries were recorded into a data tables. The date of injury was recorded as well. Two by two contingency tables were used to calculate the relative risk ratios by dividing the number of athletes with a specific injury (injuries) by the total population. Zero individuals suffered an ACL tear following a hamstring injury Therefore, the relative risk of sustaining an ACL tear with a history of hamstring injury relative to risk of ACL injury without a history of hamstring injury was 0.16 (95% CI= 0.01, 2.63). p=.198. Five individuals were found to have suffered a hamstring injury following an ACL injury; therefore, the relative risk was 1.25 (95% CI= .59,2.63). p=.57. The study reflects that individuals with a previous hamstring injury are not at higher relative risk of ACL injury compared to those without a history of hamstring injury.