The Influence of Sex, Body Mass Index, and Age on Cartilage Metabolism Biomarkers in Patients After Anterior Cruciate Ligament Injury and Reconstruction.

Context: Serum biomarkers may allow for the early identification of posttraumatic osteoarthritis after anterior cruciate ligament (ACL) injury and reconstruction. Homeostasis of matrix-metalloproteinase-3 (MMP-3) and type II collagen turnover biomarkers (C2C:CPII ratio) is believed to be compromised in individuals with ACL injury, yet the influence of sex, body mass index (BMI), and age on these biomarkers before and after ACL reconstruction remains unknown.

Objective: To determine the relationship of sex, BMI, and age with serum levels of MMP-3 and C2C:CPII before and after ACL reconstruction.

Design: Descriptive laboratory study.

Setting: Laboratory.

Patients Or Other Participants: Thirty-two (females = 18, males = 14) individuals with ACL injuries.

Main Outcome Measure(s): Demographic variables and blood samples were collected before surgery and at return to activity. Serum was extracted from the blood and assays were used to quantify MMP-3 and C2C:CPII. Generalized linear mixed-effects regression models were used to assess the relationships between sex, BMI, age, time, and participant on the outcome variables.

Results: A significant time × sex interaction was identified for MMP-3 levels (P = .021), whereby MMP-3 levels were higher in males at return to activity (males, 2.71 ± 0.59 ng/mL; females, 1.92 ± 0.60 ng/mL; P = .017). Males also had higher MMP-3 levels at return to activity when compared with presurgery levels (P = .009). A main effect for age demonstrated that older age was associated with higher MMP-3 levels. No significant main or interaction effects were noted for C2C:CPII levels.

Conclusions: Upregulation of MMP-3 serum levels may occur after ACL reconstruction, particularly in males, which may have deleterious consequences for the cartilage matrix. Sex, BMI, and time did not influence C2C:CPII ratios, but further research with larger sample sizes is needed to confirm these findings.