Body Mass Index Influences Tibiofemoral Cartilage Composition and Biochemistry in Individuals With Anterior Cruciate Ligament Injury

Context A history of anterior cruciate ligament (ACL) injury and high body mass index (BMI) are strong risk factors for incident knee osteoarthritis (KOA). Limited research has evaluated the interaction between ACL injury and high BMI on early deleterious changes in cartilage health. Objective To determine differences in T1ρ relaxation time and serum cartilage oligomeric matrix protein (sCOMP) concentration between individuals with high and normal BMI following an ACL injury. Design Cross-sectional study. Setting A controlled laboratory setting. Patients or Other Participants Forty-two participants with primary ACL injuries were assigned to either the high-BMI (>25 kg/m 2 , n = 20, age: 22.9 ± 5.1 years, time between injury and visit: 3.6 ± 2.2 weeks) or normal-BMI (≤25 kg/m 2 , n = 22, age: 21.1 ± 4.2 years, time between injury and visit: 3.3 ± 1.7 weeks) group based on their BMI. Main Outcome Measure(s) T1ρ relaxation time for the medial and lateral tibia (MTC and LTC) and femur for each participant, sCOMP concentrations, and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Results The high-BMI group, regardless of limbs, demonstrated greater T1ρ relaxation times in the LTC (mean difference: 2.1 ± 0.1 milliseconds, P = .004, d = 0.77) and MTC (mean difference: 1.7 ± 0.4 milliseconds, P = .04, d = 0.44) knees compared with the normal-BMI group. The high-BMI group showed greater concentrations in sCOMP compared with the normal-BMI group (mean difference: 26.4 ± 15.8 ng/mL, P = .02, d = .72). There were no differences in KOOS scores between groups. Conclusions Overweight individuals experiencing primary ACL injuries exhibit higher T1ρ relaxation times in both their injured and uninjured limbs and sCOMP concentrations compared with normal-weight individuals with primary ACL injuries. Our findings indicate that BMI significantly impacts cartilage composition and biochemical changes associated with KOA development in individuals with ACL injuries within 3.5 weeks of injury.