Background:Anterior cruciate ligament (ACL) rupture occurs predominantly in young patients. About 30% of individuals with this lesion will present with osteoarthritis within 20 years following the trauma, despite successful treatment. This can be explained by metabolic changes occurring concomitantly with the trauma that results in the injury to this ligament. Using analysis of biomarkers related to cartilage degeneration, we aimed to determine that soon after the trauma leading to ACL rupture there are intra-articular metabolic changes in the knee that could lead to cartilage degeneration. Methods:A cross-sectional study was carried out in two groups: patients with an ACL ruptures and a control group (each group with ten male subjects, age range 18 – 35 years, body mass index below 30 kg/m2). In both groups, urine concentrations of a biomarker related to degradation of type II collagen (CTX-II) was measured. For the group with ACL rupture, a temporal relationship between time post-injury and amount of the biomarker was also examined. Results:There were significant differences in the concentrations of urinary CTX-II between the ACL group and the control group (p = 0.009). No significant relationship was observed between time of injury and the quantity of the biomarker. Conclusions:Patients with ACL injury had higher concentrations of urinary CTX-II biomarker than those with no ACL injury (p = 0.009). However, there was no correlation between the concentration of this biomarker and the elapsed time post-injury (p > 0.05). Keywords: osteoarthritis; biomarkers, ACL injury, CTX-II