HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL STUDIES OF THE EFFECTS OF EXPERIMENTAL ANTERIOR DISC DISPLACEMENT ON SULFATED GLYCOSAMINOGLYCANS, HYALURONIC-ACID, AND LINK PROTEIN OF THE RABBIT CRANIOMANDIBULAR JOINT

Purpose: The purpose of this study was to determine the effects of sur gically induced anterior disc displacement (ADD) on sulfated glycosami noglycans (GAGs) such as keratan sulfate (KS), chondroitin-4-sulfate ( C4S), and chondroitin-6-sulfate (C6S), hyaluronic acid (HA), and link protein (LP) of-the rabbit craniomandibular joint (CMJ) using histoche mical and immunohistochemical techniques. Materials and Methods: The r ight joint of 20 rabbits was exposed surgically, and ail discal attach ments were severed except for the posterior attachment. The disc was t hen repositioned anteriorly and sutured to the zygomatic arch. The lef t joint sewed as a sham-operated control. Ten additional joints were u sed as nonoperated controls. Deeply anesthetized rabbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits ) after surgery. Discs, bilaminar zones, condyles, and articular emine nces were excised. Condyles and articular eminences were decalcified i n ethylenediaminetetraacetic acid (EDTA). All tissues were sectioned a t 10 mu m in a cryostat. Sections were incubated with alcian blue and monoclonal antibodies directed against KS, C4S, C6S, HA, or LP. After incubation in the appropriate fluorescein isothiocyanate (FITC)-labele d secondary antibodies, tissue sections were studied under the fluores cence microscope. Results: The results showed a reduction in alcian bl ue staining and KS, C4S, C6S, HA, and LP immunostaining in the disc an d articular surfaces at 2 weeks after induction oi ADD, This reduction was followed by an increase in their immunostaining at 6 weeks. Also, there was a progressive increase in alcian blue staining, and KS, C4S , C6S, and HA immunostaining in the bilaminar zone at 2 and 6 weeks. C onclusion: It was concluded that surgical induction of ADD in the rabb it CMJ leads to alterations in KS, C4S, CBS, HA, and LP content, consi stent with similar changes accompanying osteoarthritis is of other syn ovial joints.