DETECTION OF TYPE II COLLAGEN DEGRADATION BY URINARY CTX-II IN PATIENTS WITH MINIMAL LESIONS OF KNEE CARTILAGE IN ARTHROSCOPY

Purpose: The urinary C-terminal telopeptide of type II collagen (u-CTx-II) is a well-known biomarker of cartilage degradation. However, it is not clear what kind and extent of cartilage lesions are reflected by an increased urinary output of CTx-II. In this study we correlated u-CTx-II excretion with different arthroscopic findings in patients with knee joint complaints.Methods: Altogether, 168 consecutive arthroscopy patients (87 M, 88 F), aged 32-60 (mean 45) yrs, and 46 controls were included. The status of joint cartilage in the three knee joint compartments was assessed on the VAS scale. In addition, severity of cartilage lesions was assessed by the SFA (French Society of Arthroscopy) system. Synovitis was graded on a scale 0-3. The u-CTx-II, assayed by ELISA (IDS), was expressed as ng/mmol of creatinine. Results: Male controls had higher values of u-CTx-II than females. In female patients the output of u-CTx-II correlated positively with age and severity of tibial and femoral cartilage lesions (macroscopic assessment). Median of the SFA score in tibiofemoral medial compartment varied between 3 (males) - 8 (females). In patellofemoral compartment it was 3 (males) - 6 (females), respectively. Significant correlation was found between SFA score of medial tibiofemoral compartment and u-CTx-II. Positive correlations were also observed between degree of synovitis and u-CTx-II. Regression model revealed an important contribution of age and tibiofemoral SFA score to u-CTx-II (up to 28 % of the variability of u-CTx-II). In male patients whose cartilage lesions tended to be less expressed, the above correlations were not observed. Conclusions:•In middle-aged patients the urinary output of CTx-II is dependent on gender and age.•In female patients u-CTx-II was associated with cartilage lesions in the medial tibiofemoral compartment and by synovitis (independent factors).•Although we measure u-CTx-II as systemic output, it seems to be a sensitive sign of knee cartilage damage.