Changes in serum biomarkers of cartilage turnover after anterior cruciate ligament injury

Background: Biomarkers of cartilage turnover and joint metabolism have a potential use in detecting early degenerative changes after a traumatic knee joint injury; however, no study has analyzed biomarkers before an anterior cruciate ligament (ACL) injury and again after injury or in comparison with a similar group of uninjured controls. Hypothesis: Changes in serum biomarker levels and the ratio of cartilage degradation to synthesis, from baseline to follow-up, would be significantly different between ACL-injured patients and uninjured controls. Study Design: Case-control study; Level of evidence, 3. Methods: This case-control study was conducted to examine changes in serum biomarkers of cartilage turnover following ACL injury in a young athletic population. Specifically, 2 markers for type II collagen and aggrecan synthesis (CPII and CS846, respectively) and 2 markers of types I and II degradation and type II degradation only (C1,2C and C2C, respectively) were studied. Preinjury baseline serum samples and postinjury follow-up samples were obtained for 45 ACL-injured cases and 45 uninjured controls matched for sex, age, height, and weight. Results: Results revealed significant decreases in C1,2C ( P = .042) and C2C ( P = .006) over time in the ACL-injured group when compared with the controls. The change in serum concentrations of CS846 from baseline to follow-up was also significantly different between the ACL-injured patients and uninjured controls ( P = .002), as was the change between groups in the ratio of C2C:CPII over time ( P = .013). No preinjury differences in the ratio of C1,2C:CPII or C2C:CPII were observed between groups; however, postinjury differences were observed for both ratios. Conclusion: Changes in biomarker concentrations after an ACL injury suggest an alteration in cartilage turnover and joint metabolism in those sustaining ACL injuries compared with uninjured matched controls.