This thesis examined neuromuscular and biomechanical adaptations associated with anterior cruciate ligament (ACL) rupture and reconstruction (ACLR). Studies utilized novel, non-invasive brain stimulation techniques to examine the cortical response to ACL injury and ACLR, gaining new insights into quadriceps neuromuscular dysfunction in these cohorts. The relationship between quadriceps neuromuscular function and knee joint biomechanics was explored in individuals with an ACLR. The results provide new avenues for research and therapeutic targets for rehabilitation.