Serum markers of systemic disease processes in osteoarthritis.

Serum levels of several molecules originating from joints and cartilages have been shown to rise during the preradiological stages of osteoarthritis (OA). Using a dog model of posttraumatic OA, we have shown that serum levels of markers of aggrecan degradation (antigenic keratan sulfate) and synovial proliferation/metabolism (hyaluronan) rise within 1-2 weeks after the injury and remain elevated for at least 13 weeks. These changes, which precede the development of OA lesions, are consistent with the view that traumatic injury to a single synovial joint gives rise to a state of hypermetabolism that is local at first but becomes systemic with time.