ABSTRACT
PURPOSE: To demonstrate the presence of nerve fibers including nociceptive fibers in synovium of human knee joint using immunohistochemistry. MATERIALS AND METHODS: 10 Synovial membrane tissues of knee joint obtained from 5 cadavers were analyzed immunohistochemically using antibodies to protein gene product 9.5, betaIII-tubulin, substance P and calcitonin gene-related peptide (CGRP). RESULTS: Many nerve fibers immunoreactive for protein gene product 9.5 and betaIII-tubulin were demonstrated in synovial folds of human knee joints. Also, immunostaining showed the presence of free nerve ending fibers immunoreactive for substance P and calcitonin gene-related peptide in synovium. CONCLUSION: The presence of putative nerve fibers including nociceptive fibers in synovial folds supports a possible role for theses structures as source of knee joint pain.