Expression of Collagen Type I in Unaltered and Osteoarthritic Menisci of Knee Joint.

INTRODUCTION Knee osteoarthritis is a progressive degenerative disease which affects meniscal tissue. The aim of this study was to determine the differences in collagen type I expression in macroscopically unaltered and osteoarthritic menisci, and correlate the expression with the grade of macroscopic damage, age and body mass index of patients, preoperative condition of anterior cruciate ligament, angulation and knee contracture. MATERIAL AND METHODS The control group consisted of 10 macroscopically unaltered menisci, while the experimental group had 35 osteoarthritic menisci. Besides macroscopic grading of meniscal damage, the analysis of collagen type I expression was determined by immunohistochemical staining with the corresponding antibody using semiquantitative scale scores and quantitative parameters: intensity of expression and stained area size. RESULTS The results of semiquantitative evaluation showed a statistically significant decrease in collagen type I expression in osteoarthritic menisci, which correlated with an increase in macroscopic damage grade. The results of quantitative evaluation did not show a statistically significant decrease in the expression. In posterior meniscal horns, a more intense collagen type I expression was seen in the women, as well as a positive correlation of quantitatively evaluated expression with body mass index. Collagen type I expression in the anterior horns was significantly lower in varus alignment. CONCLUSION In the semiquantitative evaluation, collagen type I expression in osteoarthritic menisci was significantly lower compared to macroscopically unchanged menisci. The decrease in the expression level correlates with the increase in the grade of macroscopic meniscal damage. There was no statistically significant difference in the quantitative evaluation of expression.