CORRELATION OF CLINICAL PARAMETERS WITH URINARY COLLAGEN TYPE II C-TELOPEPTIDE AND KNEE CARTILAGE THICKNESS MEASURED WITH ULTRASOUND IN PATIENTS WITH KNEE OSTEOARTHRITIS

BackgroundAlthough knee osteoarthritis (KOA) incidence is one of the highest among chronic diseases, no effective biomarkers are known for its management [1].ObjectivesTo estimate the relationship between the sensitive marker of matrix metalloproteinase-dependent cartilage degradation - urinary collagen type II C-telopeptide (uCTX-II) levels, patient-reported outcomes (PRO), and knee cartilage thickness measured with ultrasound (US) in patients (pts) with KOA.MethodsWOMAC questionnaire and Leken`s functional index, VAS pain by pts, knee joints US, uCTX-II levels (ng/ml; ELISA) were evaluated in 46 pts (71.7% female) with KOA, who haven`t received any medical treatment except paracetamol or NSAIDs the last 12 weeks. The mean age was 62.6±6.2, mean disease duration – 10.2±6.3 years; 63% and 27% of pts had Kellgren-Lawrence grade II and III, respectively. The knee cartilage thickness (mm) in three compartments (medial, middle, lateral) of the patellofemoral region was evaluated using a linear L50 sensor in standard sensor positions, frequency 5–12 MHz. Calculation of average thickness for each knee joint and both joints was performed. The Spearman correlation coefficient was utilized to detect the association of uCTX-II, PROs and knee cartilage thickness.ResultsThe mean values (M±σ) of WOMAC and Leken`s indices were 39±13,65 and 12±4,18, respectively. The mean value of VAS pain by pts was 57.7±16.5. The mean concentration of uCTX-II was 0.18±0.12. The means of cartilage thickness were: 1.7±0.33 for the right, 1.7±0.36 for the left, and 1.7±0.31 for both knee joints.The mean value of both knee joints cartilage thickness had significant negative moderate correlation with Leken`s index (r=-0.354, p<0.01). Leken`s and WOMAC indices significantly correlated with each other (r=0.354, p<0.01).According to VAS following tertile groups were detected: 1 group: means interval less than 50 mm; 2 group: means interval 50-64 mm; 3 group: more than 64 mm. There were negative moderate correlations between cartilage thickness of the left knee joint and Leken`s index (r=-0.513, p=0.03) and WOMAC (r=-0.535, p=0.024) only in group 1.Also, pts were divided into three groups according to disease duration: 1 group: means interval less than 7 years; 2 group: means interval 7-10 years; 3 group: more than 10 years. There were negative correlations between uCTX-II and medial, middle compartments of left knee cartilage thickness (r=-0.474, p=0.03; r=-0.592, p<0.01, respectively). WOMAC negatively correlated with cartilage thickness of the left (r=-0.517, p=0.02) and right (r=-0.435, p=0.046) knee joints. Leken`s index negatively correlated with cartilage thickness of the left knee joint (r=-0.590, p<0.01). All correlations were moderate and found in group 2.There were negative moderate correlation between uCTX-II and the mean value of middle compartments of both knee joints cartilage thickness (r=-0.538, p=0.04) and positive moderate correlation between uCTX-II and Leken`s index (r=0.561, p=0.036) in men.There were no correlations between uCTX-II and cartilage thickness of each knee joint and both joints in all pts.ConclusionCartilage thickness measured with US associated with PROs in KOA pts. At the same time, the association between uCTX-II and cartilage thickness was less pronounced, only in men and in pts with disease duration 7-10 years. In pts with VAS pain less than 50 mm and in the group of pts with 7-10 years disease duration - WOMAC and Leken`s indices negatively correlated with the thickness of the cartilage of the knee joints. In other cases, correlations didn`t represent the expected relationship between uCTX-II level and clinical, instrumental characteristics of KOA. This may be because the current level of uCTX-II characterizes only the state of cartilage metabolism at the time of examination of the patient and doesn`t show the cumulative results of previous anabolic/catabolic changes in articular cartilage.References[1]Antonioli E. Int J Clin Trials 2020;7(1):35-42.Disclosure of InterestsNone declared