To investigate longitudinal changes in concentrations of the 1/20/5D4 epitope (5D4) of keratan sulfate and total sulfated glycosaminoglycans (S-GAG) in synovial fluid and serum of dogs with cranial cruciate ligament (CCL) rupture that was repaired via intra-articular surgery.
58 dogs with a ruptured CCL and osteoarthritis of the affected (index) joint.
Prior to surgical repair of the ruptured CCL, 5D4 concentration was measured in serum and synovial fluid samples by use of an inhibition ELISA, and total S-GAG concentration was measured in synovial fluid samples by use of a direct dye-binding assay. Ruptured CCL were repaired surgically, using an intra-articular fascial graft. Dogs were reexamined 1.5, 7, and 13 months after surgery, and 5D4 and S-GAG concentrations in synovial fluid and serum were measured again.
Serum 5D4 concentrations did not change significantly during the study. Concentrations of 5D4 in synovial fluid (expressed as a ratio of S-GAG concentration) did change significantly with time. In the index joint, the 5D4:S-GAG decreased from 0.19 at the beginning of the study to 0.09 1.5 months after surgery, but 7 months after surgery, the ratio increased again to 0.20.
Results support the hypothesis that serum concentration of 5D4 is not a useful marker of osteoarthritis in dogs. Surgical intervention transiently reduced the concentration of 5D4 in synovial fluid but had no effect on S-GAG concentration.