Relationship between altered knee kinematics and subchondral bone remodeling in a clinically translational model of ACL injury

Abnormal joint kinematics are commonly reported in the acute and chronic stages of recovery after anterior cruciate ligament (ACL) injury and have long been mechanistically implicated as a primary driver in the development of post-traumatic osteoarthritis (PTOA). Though strongly theorized, it is unclear to what extent biomechanical adaptations after ACL injury culminate in the development of PTOA, as data that directly connects these factors does not exist. Using a pre-clinical, non-invasive ACL injury rodent model, our objective was to explore the direct effect of an isolated ACL injury on joint kinematics and the pathogenetic mechanisms involved in the development of PTOA. Thirty-two, sixteen-week-old Long-Evans rats were exposed to a non-invasive ACL injury. Marker-less deep learning software (DeepLabCut) was used to track animal movement for sagittal-plane kinematic analyses and micro computed tomography was used to evaluate subchondral bone architecture at days 7, 14, 28 and 56 following injury. There was a significant decrease in peak knee flexion during walking (p