Lower limb kinematics, kinetics and coordination during a land and cut task; the role of gender and previous ACL injury

Anterior cruciate ligament (ACL) injury continues to be a constant adversary to field sports athletes. Females are widely acknowledged as being at an increased risk of ACL injury, in comparison to males. Athletes who are successful in rehabilitation after surgery and return to their sport are reported to have an increased risk of repeated ACL injury and the development of osteoarthritis. The current thesis utilised a novel, maximal drop-jump land and unanticipated cutting task to assess the lower limb biomechanics of uninjured male and females, and previously ACL injured subjects (ACLr). Discrete measures of lower limb kinematics and kinetics were firstly compared between uninjured males and females, and secondly between the previously injured (PI) leg of ACLr subjects and both the contralateral non-injured (NI) leg and an uninjured subject’s control leg. The results show that females had increased hip internal rotation, the PI leg was not significantly different to the NI leg but was different to the control subject’s leg with increased hip flexion, internal knee abduction moment and transverse plane knee ROM. Lower limb coordination was assessed in the ACLr subjects and both legs of the ACLr subjects had similar coordination patterns. The PI leg however showed different coordination patterns than the control subject’s leg for a number of couplings. Movement and coordination variability were also utilised for a gender and ACLr – control comparison. The female subjects and the PI leg had lower levels of movement and coordination variability than males and the contralateral non-injured leg respectively. The PI leg however, had higher levels of movement and coordination variability than the control subject’s leg. In conclusion, females and previously ACL injured subjects may be at an increased risk of initial ACL injury and the development of osteoarthritis on the PI leg respectively, due to lower levels of movement and coordination variability. Altered biomechanics at the hip were also highlighted as a potential mechanism increasing injury risk in females and ACLr subjects.