Neurological protection during cardiopulmonary bypass/deep hypothermia

OBJECTIVE: To determine if arthroscopic synovectomy in normal and inflamed joints had temporal or site-related effects on articular cartilage. STUDY DESIGN: Alterations in equine third carpal bone articular cartilage were studied at two time periods: groups 1 and 2 (6 weeks) and groups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) and inflamed carpi (groups 1 and 3). ANIMAL POPULATION: 16 carpi from eight horses. METHODS: Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radioloabeling, proteoglycan (PG) extraction, chromatography, electrophoresis, and indentation testing. RESULTS: Synovectomy in inflamed joints produced the greatest concentration of newly synthesized PG in articular cartilage by 2 weeks. Synovectomy in normal joints produced significantly greater newly synthesized PG in articular cartilage by 6 weeks. Dorsal sites had greater newly synthesized and endogenous PG in some groups. Chromatographic profiles of newly synthesized PG demonstrated early and late PG peaks. Electrophoresis of late PG peak showed a toluidine blue-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 region 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 dorsal sites. CONCLUSIONS: Synovectomy in inflamed joints produced site-specific, significantly greater responses in articular cartilage as compared with synovectomy in normal joints. CLINICAL RELEVANCE: Synovectomy may not be beneficial to the articular cartilage in inflamed joints.