Risk factors for postoperative ecchymosis after medial open-wedge high tibial osteotomy: an exploratory analysis of...

This study aims to identify risk factors for ecchymosis and its associated coagulation characteristics following medial open-wedge high tibial osteotomy (OWHTO) using thromboelastography (TEG).

This single-center retrospective study included 220 consecutive patients undergoing unilateral medial OWHTO between January 2023 and September 2025. All patients received rivaroxaban 10 mg orally once daily for 14 days, commencing 12 h postoperatively. The primary endpoint was the incidence of peri-incisional ecchymosis, assessed daily during the hospital stay (postoperative days 1-4). Patients were categorized into ecchymosis (n = 74) and no-ecchymosis groups. Pre-operative and post-operative day-4 TEG parameters, blood loss volumes, and baseline characteristics were analyzed. Multivariable logistic regression (variables selected based on clinical relevance and univariate P < 0.10) determined independent factors, while group discrimination was assessed descriptively using AUC.

Ecchymosis occurred in 33.6% (74/220) of patients. The ecchymosis group demonstrated higher BMI (mean difference 1.57 kg/m², 95% CI 0.81-2.33, P < 0.001), prolonged tourniquet time, greater hidden blood loss, and impaired TEG-CI recovery (ΔTEG-CI: -1.04, 95% CI - 1.48 to - 0.60, P < 0.001). Multivariable analysis identified BMI (OR 1.26, 95% CI 1.11-1.43), tourniquet time (OR 1.03, 95% CI 1.01-1.05), and ΔTEG-CI (OR 0.71, 95% CI 0.56-0.91) as independently associated with ecchymosis (AUC = 0.81, 95% CI 0.75-0.87). Increased hidden blood loss correlated with ecchymosis in affected patients, suggesting a shared bleeding process rather than an independent pathogenic factor.

This exploratory single-center retrospective analysis identified BMI, tourniquet time, and impaired perioperative recovery of the coagulation index as independently associated with ecchymosis following medial OWHTO. These findings detail a post-event coagulation status in patients developing ecchymosis under consistent perioperative anticoagulation; however, they do not support temporal or predictive inferences and remain hypothesis-generating. Prospective multicenter validation is necessary before any clinical utility can be inferred.