Increased platelet, leukocyte, and endothelial cell activity are associated with increased coagulability in patients...

Orthopedic surgery, especially total knee and total hip arthroplasty, is considered a risk factor for peri-operative venous thromboembolism.

This study evaluates how accelerated inflammatogenic cellular interactions and the subsequent production of tissue factor and CD40 ligand play an important role in the pathogenesis of venous thromboembolism.

Twenty-four patients undergoing total knee arthroplasty were randomly assigned to groups with (Ti; n = 12) and without (Tn; n = 12) pneumatic tourniquet inflation.

Numbers of leukocyte-platelet aggregates, especially those comprising monocytes-platelets in central venous blood from the Ti group, were increased during the peri-operative period (P < 0.01), and returned to the baseline level at 24 h after starting surgery. Levels of PAC-1, P-selectin, CD40 ligand, tissue factor, Mac-1 expression on monocytes including monocyte-platelet aggregates, and the number of microparticles including those of endothelial cell origin were noticeably increased in central venous blood from the Ti group (P < 0.01). Whole blood coagulability was also obviously increased in central venous blood from the Ti group (P < 0.01). Furthermore, the concentrations of venous plasma tissue factor antigen, CD40 ligand, platelet factor 4, beta-thromboglobulin, the soluble fibrin monomer complex and prothrombin fragment 1+2 were also increased (P < 0.05).

This study showed that platelet, leukocyte and endothelium activities as well as their interactions are enhanced during the peri-operative period of total knee arthroplasty, particularly in venous blood from the lower half of the body, which consequently augments blood coagulability. Further, tourniquet inflation during surgery exaggerates these responses.