Due to staff departure, study is being discontinued per allocation of resources.

The proposed study will establish novel relationships between intra-articular mesenchymal stem cell (MSC) recruitment, synovial inflammation, biomarkers of cartilage degeneration and joint inflammation, clinical patient factors, and downstream alterations in cartilage composition and morphology to provide novel insights into the pathoetiology of post-traumatic osteoarthritis (PTOA) after ACL injury and reconstruction. The study aims to enroll N=38 total patients with primary, isolated rupture to their anterior cruciate ligament (ACL), who have agreed to participate in the study and who will undergo primary surgical reconstruction by an orthopaedic physician at our two sites. Patients will undergo baseline magnetic resonance imaging (MRI), baseline clinical evaluation, and undergo a baseline blood draw. Subsequent imaging and clinical evaluations will be longitudinally performed at several postoperative timepoints up to 12 months postoperatively.

Overall Study Design: This is a prospective, longitudinal cohort study of patients undergoing primary ACL reconstruction following ACL rupture. Surgical treatment and treatment timelines do not deviate from the national and international standards of care. Enrolled patients for study participation will undergo assessments involving blood, urine, and synovial fluid collection, clinical evaluation involving questionnaires and joint laxity testing, and MRI analysis.

Patient Selection and Enrollment: The participating physicians at each site will identify potential subjects from their clinics' patients according to the inclusion/exclusion criteria listed below. Based on surgical volumes at both sites, patients generally undergo ACL reconstruction 8-12 weeks after initial screening. In the preoperative timeframe, all patients will undergo standard physical therapy to address pain, swelling, and motion deficits, as is standard of care at both institutions. Arthroscopic ACL reconstruction will be performed by Dr. Bedi at the University of Michigan, by Professor Ao at Peking University, and by 5 additional surgeons at Peking University. All surgeons will utilize a standardized single-bundle technique with a hamstring or bone-patellar tendon-bone autograft.

Inclusion Criteria:

• Isolated, traumatic primary anterior cruciate ligament rupture requiring surgical reconstruction
• Surgical reconstruction performed using a single-bundle technique utilizing an autograft
• No history of ipsilateral traumatic knee injury or fracture
• No evidence of Posterior Cruciate Ligament injury or more than grade 1 injury to the Medial or Lateral Collateral Ligament

Exclusion Criteria:

• Body Mass Index < 18.5 or >35 - Injury occurred longer than 4 weeks before enrollment
• Intra-articular steroid injection within 3 months of injury
• Chondral defects greater than 3 cm2 or Outerbridge grade II or higher lesions
• Pregnant women as they are not eligible for surgery

Community sample