In this study the investigators will examine patients who have undergone unilateral ACL reconstruction surgery to determine which structural and functional characteristics of the knee two and ten years post reconstruction surgery, aspects of the original injury and repair, and patient characteristics are risk factors for osteoarthritis after ACL reconstruction surgery.

The purpose of this study is to identify risk factors for signs and symptoms of osteoarthritis two and ten year post ACL reconstruction from information available at the time of surgery. Hypothesis: Smoking status, older age, higher BMI, increased severity of cartilage injuries, increased meniscal resection, revision surgery, and incidence of additional arthroscopic procedures will result in more symptoms and signs of osteoarthritis at 10-year follow-up.

Primary outcome measures will be the joint space width measured on weight-bearing radiographs, as well as the pain subscale of the Knee Injury and Osteoarthritis Score (KOOS).

Secondary outcome measures will include the knee related quality of life subscale of the Knee Injury and Osteoarthritis Score (KOOS).

Inclusion Criteria:

• Had primary unilateral ACL reconstruction performed by Dr. Kurt Spindler (Vanderbilt University), Dr. Christopher Kaeding (The Ohio State University), Dr. Rick Parker (Cleveland Clinic), Dr. Jack Andrish (Cleveland Clinic), Dr. Rick Wright (Washington University, St. Louis), or Dr. Matthew Matava (Washington University, St. Louis).
• Participated in the 2 yr onsite visit

Exclusion Criteria:

• Unable to be consented
• Unable to participate for health reasons
• History of intra-articular knee infection
• History of total knee arthroplasty on either knee

Participants enrolled in the Multicenter Orthopaedic Outcomes Network cohort by one of study site surgeons and meeting eligibility criteria