PB0471 - Thrombelastography-Defined Duration of Hypercoagulability Following Primary Total Hip and Total Knee Arthroplasty

Background: In Canada, total hip arthroplasty (THA) and total knee arthroplasty (TKA) are commonly performed surgical procedures. Despite the use of thromboprophylaxis, the rate of venous thromboembolism (VTE) following these procedures remains high (up to 1.5%). Therefore, it is critical to quantify the duration of increased VTE risk post-operatively. Thrombelastography (TEG) is a point-of-care tool that quantifies individual coagulation profiles, where the maximal amplitude parameter (MA; a measure of clot strength) can define hypercoagulability (MA ≥ 65mm) and increased VTE risk post-operatively.

Aims: To utilize serial TEG analysis to define the duration of hypercoagulability and increased VTE risk, following THA or TKA.

Methods: Consecutive patients 50 years of age or older undergoing a primary THA or TKA were enrolled in this prospective cohort (REB 19-1251). Patients were excluded if they had a history of VTE, bleeding disorder, active malignancy, or were on therapeutic anticoagulation. Following informed consent, serial TEG-based whole blood analysis was performed until 12-weeks post-operatively. Thromboprophylaxis was standardized to acetylsalicylic acid 81 mg daily. One-sample t-tests were performed to compare mean MA values to the previously established hypercoagulability threshold of ≥ 65mm. All statistical tests were two-sided, with a p-value of < 0.05.

Results: Twenty-five patients were enrolled (70.8 ± 8.0 years; 56% female). At two weeks post-operatively, 94% of all patients remained hypercoagulable (MA = 70.9 ± 3.3, p < 0.001). However, only those who underwent TKA were significantly hypercoagulable (MA = 71.4 ± 2.1, p < 0.001). Hypercoagulability persisted in 76% and 63% of patients at four and six weeks post-operatively, respectively (Figure 1). To date, eight patients have completed the 12-week follow-up, with 75% returning to baseline normal coagulation status. There were no VTE events observed in this sample.

Conclusion(s): Most patients demonstrated hypercoagulability beyond the recommended thromboprophylaxis duration, supporting further investigation to optimize thromboprophylaxis duration following THA and TKA.