CHANGES IN 3RD CARPAL BONE ARTICULAR-CARTILAGE AFTER SYNOVECTOMY IN NORMAL AND INFLAMED JOINTS

Objective-To determine if arthroscopic synovectomy in normal and infla med joints had temporal or site-related effects on articular cartilage . Study Design-Alterations in equine third carpal bone articular carti lage were studied at two time periods: groups 1 and 2 (6 weeks) and gr oups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) an d inflamed carpi (groups 1 and 3). Animal Population-16 carpi from eig ht horses. Methods-Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radiolabeling, prote oglycan (PG) extraction, chromatography, electrophoresis, and indentat ion testing. Results-Synovectomy in inflamed joints produced the great est concentration of newly synthesized PG in articular cartilage by 2 weeks. Synovectomy in normal joints produced significantly greater new ly synthesized PG in articular cartilage by 6 weeks. Endogenous PG was only significantly greater in inflamed joints after 6 weeks. Dorsal s ites had greater newly synthesized and endogenous PG in some groups. C hromatographic profiles of newly synthesized PG demonstrated early and late PG peaks. Electrophoresis of late PG peak showed a toluidine blu e-positive band that comigrated with human A1D1 PG monomer in the two groups with the most newly synthesized PG. This band was reactive with monoclonal antibody 1C6 specific for the hyaluronic acid-binding regi on of aggrecan. For the material properties evaluated, only Poisson's ratio was significantly decreased between groups as a function of time (6 weeks < 2 weeks), and this was most pronounced in the thicker dors al sites. Conclusions-Synovectomy in inflamed joints produced site-spe cific, significantly greater responses in articular cartilage as compa red with synovectomy in normal joints. Clinical Relevance-Synovectomy may not be beneficial to the articular cartilage in inflamed joints. ( C)Copyright 1998 by The American College of Veterinary Surgeons.