Effects of anterior cruciate ligament reconstruction on the association between quadriceps muscle dynamics, knee joint biomechanics, and articular cartilage loading during walking

点击翻译按钮获取中文摘要

PROJECT SUMMARY Individuals with anterior cruciate ligament reconstruction (ACLr) walk with smaller than typical peak knee extensor moments (pKEM) and diminished knee flexion excursion during the weight acceptance phase of walking. These deficits in voluntary quadriceps activation are considered critical in the biomechanical cascade underlying disproportionally high rates of post-traumatic osteoarthritis (PTOA) in individuals with ACLr. It has been suggested that changes in gait biomechanics at the knee joint can shift articular contact forces to regions not conditioned to loading, particularly when the event allows little time for cartilage adaptation. The gait changes observed in individuals with ACLr likely result from a combination of weakness and central inhibition during functional activities and must be addressed with a novel rehabilitation strategy because quadriceps strengthening alone appears unable to return gait biomechanics to uninjured values. This will be the first study to establish mechanistic links between quadriceps kinematics, deficits in voluntary force production, and maladaptive cartilage loading patterns in individuals with ACLr. The proposed research will use a multi-scale approach with novel applications of gait biofeedback, in vivo ultrasound imaging, and cutting-edge knee joint simulations. Through our pilot in vivo ultrasound testing, we observe a fundamentally different behavior in quadriceps activation between ACLr and uninjured controls. Differences in muscle fascicle length change may be a functional consequence of quadriceps dysfunction relevant to altered knee loading. The proposed research builds upon this concept to evaluate quadriceps contractile dynamics during tasks requiring different functional demands to strategically assess the effects of modulating pKEM in individuals with ACLr. Furthermore, the proposed research will evaluate how systematic changes in quadriceps activation and knee joint biomechanics cued via biofeedback or walking speed affect cartilage contact forces. The proposed research will have immediate impact on our understanding of the contributions of quadriceps activation deficits in PTOA development following ACLr.