Differences in ACL biomechanical risk factors between field hockey and lacrosse female athletes.

PURPOSE: Previous investigations have revealed a greater incidence of anterior cruciate ligament (ACL) injuries in female lacrosse versus field hockey players. Lacrosse is played in an upright posture with overhead throwing and catching, while field hockey is almost exclusively played in a crouched, forward-flexed position. Biomechanical factors, including decreased knee, hip, and trunk flexion angles, have been identified as risk factors for ACL injury. The purpose of this study was to assess ACL biomechanical risk factors in female field hockey and lacrosse players to determine whether sport-specific posture might contribute to the increased incidence of ACL injury observed in lacrosse athletes. METHODS: Thirty-one Division I NCAA females from field hockey and lacrosse completed four tasks, three times per leg: bilateral drop jump, single-leg drop jump (SDJ), single-leg jump onto a Bosu ball (SDB), and a 45° anticipated cut. Kinematic and force plate data were used to evaluate knee flexion angle, knee adduction moment, hip flexion angle, and trunk flexion and sway angles. Muscle activity of the lateral hamstrings and vastus lateralis was used to estimate peak hamstring activity and the quadriceps/hamstring ratio at the time of peak quadriceps activity (co-contraction ratio). RESULTS: During the SDJ and SDB, peak knee flexion angles were greater in field hockey compared with lacrosse. During cutting, field hockey players were more flexed at the trunk and had greater trunk sway, compared with the lacrosse players. No significant difference was observed for the co-contraction ratio for any of the tasks. CONCLUSIONS: Decreased knee flexion angle during landing, consistent with sport-specific playing postures, may contribute to the higher incidence of ACL injury in lacrosse players relative to field hockey. Sport-specific training injury prevention programmes may benefit from considering these differences between specialized athletes. LEVEL OF EVIDENCE: II.