Inclusion Criteria:  Age 16 to 35 years Unilateral, primary ACLR with bone-patellar tendon-bone autograft  Exclusion Criteria:  History of prior ACL injury or revision ACLR History of prior knee surgery Requirement of multiple ligament surgery at time of ACLR Concomitant injuries or surgical procedures at the time of ACLR that would delay early post-operative weight bearing based on surgeon recommendations (e.g. lower extremity fracture, intra-articular fracture, microfracture procedure) Removal of more than 1/3 of the medial or lateral meniscus at the time of ACLR Articular cartilage damage greater than 3A on the International Cartilage Repair Society Criteria at the time of ACLR History of musculoskeletal injury to either leg in the 3 months prior to participation other than primary ACL injury Prior diagnosis of radiographic OA in any joint of the lower extremity History of neurological disorder (e.g. stroke, multiple sclerosis, etc.) Contraindications for MRI (e.g. extreme claustrophobia, cardiac pacemaker, cochlear implant, metal foreign bodies, aneurism clip, etc.) Pregnant or planning to become pregnant