COMPARISON OF SYNOVIAL-FLUID CARTILAGE MARKER CONCENTRATIONS AND CHONDRAL DAMAGE ASSESSED ARTHROSCOPICALLY IN ACUTE KNEE INJURY

Objective: To examine the correlation between synovial fluid cartilage markers and degree of cartilage damage determined by arthroscopic eva luation in subjects with acute knee injury. Design: Chondral damage wa s quantified using a validated arthroscopic scoring system in 20 subje cts with effusive acute knee injuries of less then 4 months duration a nd no history or radiographic evidence of joint pathology. Levels of s ynovial fluid 3B3(-) neoepitope, 3B3(+) chondroitinase generated epito pe of proteoglycan, keratan sulfate (KS) and hyaluronic acid (HA) were measured by competitive enzyme-linked immunosorbent assays using mono clonal antibodies 3B3 and 5D4. Total sulfated glycosaminoglycan (GAG) was measured by 1,9-dimethylmethylene blue colorimetric dye-binding as say. Results: We found a dramatic decrease in levels of 3B3(-) (r(s) = -0.62, P = 0.004), and GAG (r(s) = -0.49, P = 0.03) with increasing c hondral damage score; but no correlation of damage score with 3B3(+), KS or HA levels. Conclusion: These data reveal a change in cartilage m etabolism within the first 4 months of symptomatic knee injury evinced by a significant inverse correlation of 3B3(-) and GAG levels to chon dral lesion severity. These results suggest that serial measurement of these synovial fluid markers in the setting of acute knee injury coul d predict chondral lesion severity and aid in the decision to interven e surgically.