The Effect of Previous Hamstring Injuries on ACL Injury Risk

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