MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL EXAMINATION OF NERVES IN NORMALAND INJURED COLLATERAL LIGAMENTS OF RAT, RABBIT, AND HUMAN KNEE JOINTS

Background: Knee joints possess an abundant nerve supply that relays s ensory and motor information on such aspects as proprioception, nocice ption, and vasoregulation. Although synovial innervation has been well documented, little is known of the nerves that supply the collateral ligaments. Methods: The morphology of rabbit and human collateral liga ment nerves was examined by silver impregnation, Immunohistochemistry was performed on rabbit and rat collateral ligaments to determine the presence of peptidergic nerves in these tissues. A 6-week gap injury w as performed on three rabbit medial collateral ligaments, and the loca lisation of peptidergic nerves in these tissues was determined. Result s: Irrespective of species or type of ligament examined, the greatest density of nerve fibres was found in the epiligament. Nerve fibres com monly accompanied blood vessels along the long axis of the ligament an d then entered the substance of the tissue before ramifying in the dee per layers, Substance P and calcitonin gene-related peptide-immunoreac tive nerve fibres were found in the collateral ligaments of the rat an d rabbit, Injured ligaments showed a higher than normal level of immun oreactivity in and around the healing zone; however, the nerve fibres appeared tangled and truncated. Conclusions: Like other structures in knee joints, collateral ligaments possess a complex nerve supply, The presence of peptidergic nerves suggests that ligaments may be suscepti ble to neurogenic inflammation and may be centres of articular nocicep tion. (C) 1997 Wiley-Liss, Inc.