Articular Cartilage Differences Between Those With High And Normal Body Mass Index Following Acl Injury

PURPOSE: Those with an anterior cruciate ligament (ACL) injury are at higher risk for developing knee osteoarthritis. However, little is known about how high body mass index (BMI), a strong risk factor for knee osteoarthritis development, affects cartilage prior to ACL reconstruction (ACLR) in those with acute ACL injuries. The purpose of this study was to determine differences in osteoarthritis-related biomarkers of T1ρ relaxation time and serum cartilage oligomeric matrix protein (sCOMP) concentration between individuals with high and normal BMI following an ACL injury. METHODS: Forty-two participants with primary ACL injuries who were seeking ACLR were dichotomized into either the high-BMI (>25 kg/m2; n = 20; 22.9 ± 5.1 years; days between injury and visit: 25.2 ± 15.4) or normal-BMI (≤25 kg/m2; n = 22; 21.1 ± 4.2 years; days between injury and visit: 23.1 ± 11.9) group based on their BMI at their preoperative visit. We used spin-locked T1ρ MR sequence to quantify T1ρ relaxation times to estimate proteoglycan density in the tibiofemoral articular cartilage composition. T1ρ relaxation times were calculated for the medial and lateral tibia (MTC and LTC) and femur (MFC and LFC) for each participant. Separate mixed-model ANOVAs were used to determine differences in T1ρ relaxation times across the regions of interests between the high- and normal-BMI groups in both the injured and uninjured limbs. An independent t-test was used to determine differences in sCOMP concentration between groups. RESULTS: The high-BMI group demonstrated greater T1ρ relaxation times in the LTC (50.1 ± 2.6 vs 48.0 ± 2.4 ms; p = 0.004; d = 0.77) and MTC (51.8 ± 5.2 vs 49.4 ± 3.4 ms; p = 0.04; d = 0.44) in both limbs compared to the normal-BMI group. The high-BMI group also showed greater concentrations of sCOMP compared to the normal-BMI group (148.8 ± 44.4 vs 122.4 ± 28.6 ng/mL; p = 0.02; d = 0.72). CONCLUSIONS: These findings suggest that BMI may impact bilateral articular cartilage composition and systemic biochemical changes linked to knee osteoarthritis development in individuals with acute ACL injuries. Individuals with BMI >25 kg/m2 may exhibit a predisposition for greater articular cartilage breakdown even prior to ACLR, which is important for guiding therapeutic interventions to prevent knee osteoarthritis in this patient population. Supported by: Arthritis Foundation and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (T32AR082310 and P30AR072580).