Procollagen IIC-peptide as a marker for assessing mechanical risk factors of knee osteoarthritis: effect of obesity and varus alignment

Abstract

Objective: To ascertain by cross sectional examination whether the concentration of procollagen IIC-peptide in joint fluid significantly correlates with mechanical risk factors of knee osteoarthritis (OA), such as obesity (body mass index) and varus alignment (lateral femorotibial angle).

Methods: The concentrations of procollagen IIC-propeptide in synovial fluid were measured by a sandwich enzyme immunoassay of 65 patients with the same radiological stage of primary knee OA-that is, Ahlbäk stage I. The relations between procollagen IIC-peptide and body mass index and lateral femorotibial angle were examined using simple regression analysis and multiple regression analysis.

Results: Significant positive correlations were found between procollagen IIC-propeptide concentrations and body mass index (r=0.479, p<0.0001), and between procollagen IIC-propeptide concentrations and lateral femorotibial angle (r=0.375, p=0.0021). Significant correlations were also found by multiple regression analysis. The multiple correlation coefficient of body mass index and femorotibial lateral angle to the procollagen IIC-propeptide concentrations was 0.547 (p<0.0001).

Conclusions: The findings suggest that synthesis of type II collagen by chondrocytes is enhanced by abnormal mechanical stress, in this case obesity and varus alignment. It is concluded that procollagen IIC-propeptide concentrations in joint fluid are a useful marker of early OA.

Figures

Figure 1

Correlation between procollagen IIC-peptide concentrations and body mass index (BMI). Procollagen IIC-propeptide concentrations in joint fluid were measured by enzyme immunoassay. Significant correlations were found between procollagen IIC-propeptide concentrations in joint fluid and BMI in 65 patients with primary knee osteoarthritis, Ahlbäk stage I (r=0.479, p

Figure 2

Correlation between procollagen IIC-peptide concentrations and lateral femorotibial angle (FTA). Significant correlations were also found between procollagen IIC-propeptide concentrations in joint fluid and the FTA in 65 patients with primary knee osteoarthritis, Ahlbäk stage I (r=0.375, p=0.0021).