Knee osteoarthrosis (OA) is a degenerative disease with progressive loss of cartilage of joints and bone destruction. During this process, the release of fragments of connective tissue matrix is detected in the biological fluids such as human cartilage glycoprotein (YKL-40), cartilage oligomeric matrix protein (COMP) and collagen type I C terminal telopeptid (CTX-I).
The aim of the study was to determine the degree of connection cartilage thickness measured by ultrasound with serum concentrations of biomarkers YKL-40, COMP and CTX-I in patients with primary knee OA.
The analysis included 88 patients with the diagnosis of knee OA. Ultrasound examination of knees were done by two rheumatologists. The analysis of serum samples determined the concentration of COMP, YKL-40 and CTX-I by the ELISA method.
The average age of patients was 69.97 +/- 9.37 years and the duration of knee OA 6.46 +/- 6.73 years. The average cartilage thickness of the femoral condyle was 1.33 +/- 0.20 mm; of the medial condyle (MC) (front access) 1.30 +/- 0.23 mm, (rear access) 1.30 +/- 0.29 mm and lateral condyli (LC) (front access) 1.39 +/- 0.27 mm. The average cartilage thickness of MC (front access) was 1.27 mm (0.98-1.42 mm), (rear access) 1.27 mm (0.84-1.46 mm) and LC (front access) 1.36 mm (1.01-1.57 mm) (p = 0.002). There was a significant connection in the negative direction between the patients' age and the cartilage thickness of MC (front and rear access) and LC (front access) (r = -0.253; p = 0.017). There was a significant negative direction of interrelationship between the cartilage thickness of MC (front access) (r = -0.259; p = 0.015) and LC (front access) and the disease duration (r = -0.259; p = 0.015). In patients with knee OA lasting for 5 years the measured cartilage thickness was 1.27 mm (1.16-1.49 mm), and 0.99 mm (0.94-1.23 mm) (p = 0.007) in those lasting for 20 years. There was a significant relationship in a negative direction between the concentration of YKL-40 and cartilage thickness of MC (front access) (r = -0.249; p = 0.019).
The progressive loss of cartilage during the long-term evolution of osteoarthrosis is most extensive in the femoral MC. The increased serum levels of YKL-40 can be a good indicator of joint cartilage destruction.