Blood Coagulation at Major Orthopaedic Surgery

Thromboelastography (TEG) provides a means of monitoring coagulation postoperatively, the triggers involved are not clear. We studied the TEG parameters after total hip arthroplasty (THA), exploring the relationship with markers of hemostasis. In samples collected from 61 patients (33-72 years old), TEG parameters, global coagulation indices and specific hemostatic markers (TAT, D-dimer, and β-thromboglobulin) were assessed. Blood samples were taken before THA, 30 min after completion of surgery, and post-THA (Days 1, 3, 7, and 14). TAT levels peaked upon completion of THA, declining on Day 1 and normalizing by Day 3; β-thromboglobulin levels increased sharply to peak upon completion of THA, returning to baseline levels after Day 7; and the TEG coagulation index (CI) of whole blood increased immediately after THA, peaked within 7 days, and remained elevated for up to 14 days. After surgery (30 min), CI correlated significantly with platelet count (r=0.31, p<0.05) and β-thromboglobulin level (r=0.60, p<0.05). On postoperative Day 1, CI correlated with fibrinogen level (r=0.42, p<0.05) and platelet count (r=0.36, p<0.05). By Day 3, a correlation between CI and activity of the external coagulation pathway was noted. CI and PT also correlated significantly on Day 7 (r=-0.45, p<0.05) and Day 14 (r=-0.47, p<0.05). D-dimer concentration increased sharply at completion of surgery, declined at Day 3, rose again by Day 7, and remained elevated until Day14. On the other hand, the whole blood lysis index (Ly30) was unchanged at completion of surgery and during postoperative Day 1, increased significantly on Day 3, and then returned to baseline levels by Day 7. In conclusion, thrombin formation after major orthopedic surgery declines; but the total coagulation potential of blood (under standard anticoagulant treatment) peaks within one week and remains elevated at least until postoperative Day 14, correlating with activity of the external coagulation pathway during this time