BACKGROUND: Intraarticular exudate, observed in the knee joint a few weeksafter a traumatic incident, is one of post-traumatic complications. Evacuation of the exudate preventsdamage of the articular cartilage by the fluid possessing potent proteolytic properties. In view of thelack of data concerning the role of the fibrinolysis system in proteolytic destructive processes inducedby the exudate, the aim of the study was to find out whether plasmin is present in the post-traumaticintraarticular exudate and whether it is generated in connection with excessive plasminogen activatorlevels or deficiency of plasminogen activator inhibitors in the synovial fluid. MATERIAL/METHODS: 55patients (mean age 35.1), with history of knee joint traumas and exudate appearing in the joint at least3 weeks post-traumatically. The patients and 30 healthy controls were subjected to the following testsof the synovial fluid and plasma: the levels of tissue plasminogen activator, type 1 plasminogen activatorinhibitor, plasmin-alpha 2-antiplasmin complexes, fibrinogen and von Willebrand factor antigen, the activityof urokinase plasminogen activator, prekallikrein, alpha-2-antiplasmin, C1 inhibitor, type 1 plasminogenactivator inhibitor, euglobulin clot lysis time. RESULTS: The patients' plasma demonstrated significantlyhigher levels of fibrinogen and PAP complexes, and decreased u-PA activity in comparison in that obtainedfrom the controls. Significantly higher levels of PAP complexes and u-PA antigen were found in the exudatethan in the patients' plasma. CONCLUSIONS: Local, intraarticular plasmin generation, probably u-PA-dependent,occurs in knee joint exudate. Plasminogen activator inhibitors are probably not very closely associatedwith increased intraarticular plasminogenesis.

Keywords: Adolescent, Antiplasmin, Complement 1 Inactivators, Enzyme-Linked Immunosorbent Assay, Exudates and Transudates, Joint Diseases, Knee Injuries, Knee Joint, Plasmin, Plasminogen, Plasminogen Activator Inhibitor 1, Plasminogen Inactivators, Research Support, Non-U.S. Gov, Synovial Fluid, Time Factors, Urinary Plasminogen Activator