Initial Graft Tension and ACL Surgery

Inclusion Criteria for Groups 1 and 2: * ACL injury of only one knee (minor meniscal tears involving less than 1/3 of the meniscus are allowed) * Candidate for ACL reconstruction surgery using a bone-patellar tendon-bone graft or a four-stranded hamstring tendon graft (looped semitendinosus and gracilis muscles) * Tegner activity score of 5 or greater, indicating participant is at least moderately active Exclusion Criteria for Groups 1 and 2: * ACL tear that has occurred more than 12 months prior to surgery * Moderate-sized fissures or lesions in knee articular cartilage * Meniscal tears requiring partial removal of meniscus (tears larger than 1/3 of the meniscus) Inclusion Criteria for the Control Group: * Tegner activity score of 5 or greater, indicating participant is at least moderately active Exclusion Criteria for All Participants: * Previous injury to either knee * Increased laxity of the medial collateral ligament (MCL), lateral collateral ligament (LCL), or posterior cruciate ligament (PCL), as compared to the uninjured knee * Radiographic evidence of degenerative arthritis * Pregnancy * Any disease that might place a participant at high risk for articular cartilage damage (e.g., rheumatoid arthritis, osteoporosis, metabolic diseases)