Optimizing Movement After Anterior Cruciate Ligament Injury

Fifty percent of teenagers and young adults who suffer an anterior cruciate ligament (ACL) injury develop radiographic knee osteoarthritis (OA) within 15 years. The resulting pain, reduced quality-of-life, and increased risk for co-morbidity lead to substantial healthcare costs, inability to fulfill work and personal responsibilities, and reduced long-term health. Degeneration in articular cartilage, connective tissue that covers the ends of bones in the knee, is the hallmark of early OA development after knee injury. This deterioration can be measured by increased T2 and T1rho relaxation time on quantitative magnetic resonance imaging (MRI), an imaging biomarker for OA development. Harmful increases in MRI markers of the knee's articular cartilage occur within months of ACL injury and indicate preventative interventions should begin soon after injury. However, evidence-based interventions to prevent OA do not exist. The investigators have shown that after ACL reconstruction (ACLR), patients exhibit asymmetric movement patterns characterized by up to 62% lower knee joint loading during walking and squatting in the injured limb at two months after ACLR. These knee joint loading patterns remain 40% lower at six months. Emerging evidence suggests knee joint unloading patterns after ACL injury may increase the risk for OA development. Currently, no studies have examined the efficacy of movement-focused interventions during the first months after ACLR, which explains the lack of evidence-based interventions that successfully increase knee loading early after ACLR. This gap presents a barrier to the long-term goal of preventing OA in young, active individuals before irreversible knee degeneration occurs. This project will challenge the traditional OA paradigm that too much joint loading (e.g. "wear and tear") causes cartilage breakdown. The multi-disciplinary team spanning rehabilitation, orthopaedics, radiology and biomechanics has developed a novel visual biofeedback paradigm using portable force plates that can increase knee loading during squats within a single session after ACLR. This data suggest movement is modifiable using visual feedback, but its efficacy beyond a single training session is unknown. This study will determine the efficacy of the visual biofeedback program initiated two weeks after ACLR by assessing movement biomechanics and MRI changes in cartilage microstructure six months later. Successful completion of this project will establish the first rehabilitation intervention to effectively and optimally load the knee joint early after ACLR, providing the initial steps in the team's work to prevent OA after ACL injury.