Distribution of substance P nerve fibers in osteoarthritis knee joint

The objective of the study was to evaluate the distribution of substance P-immunoreactive nerve fibers in osteoarthritis knee and to determine whether a degenerative disease has any influence on the occurrence of neuropeptide-containing fibers, positively stained for substance P. Twenty consecutive patients, 16 females and 4 males, with gonarthrosis participated in the study. For comparison we used the group of 20 patients, 14 females and 6 males, operated on because of traumatic lesion of the knee. The medial and lateral retinaculum, medial compartment synovium and infrapatellar fat pad of these two groups of patients were evaluated using monoclonal antibody to substance P (PEPA40, Serotec Ltd, UK). The slices were examined semi-quantitatively for nerve fibers showing substance P expression. The values were analyzed with ONE WAY ANOVA test, which was then corrected with LSD test, at the level of significance p<0.05. There were no statistical differences in distribution of substance P nerve fibers in the fat pad, lateral and medial retinaculum or synovium between both groups, as well as in the each study group (p<0.05). The results allow us to speculate that different biomechanical axial disturbances of the knee could have the same influence on substance P-positive mechanoreceptors of the soft tissues around the joint modulating the pain pathway in knee osteoarthrosis.