Phenotype-informed management of preoperative asymptomatic isolated muscular calf vein thrombosis in patients undergoing primary total knee arthroplasty under standardized thromboprophylaxis: a retrospective cohort study

Background Limited evidence exists regarding the management of preoperative screen-detected (by duplex ultrasonography) asymptomatic isolated muscular calf vein thrombosis (MCVT) before total knee arthroplasty (TKA). We evaluated the outcomes when TKA was performed as scheduled, without preoperative therapeutic-dose anticoagulation, using a standardized thromboprophylaxis and enhanced recovery after surgery (ERAS) pathway. Methods Consecutive adults undergoing primary unilateral TKA from 2019 to 2023 received bilateral duplex ultrasonography within 5 days before surgery. The MCVT group comprised patients with asymptomatic isolated gastrocnemius or soleal vein thrombosis, with no involvement of axial deep calf veins or the popliteal vein; the control group had no thrombosis. All patients received a standardized pharmacological prophylaxis regimen (enoxaparin in-hospital followed by rivaroxaban after discharge, total duration 14 days), along with mechanical prophylaxis and early mobilization. The primary outcome was symptomatic venous thromboembolism (VTE) within 90 days. Secondary outcomes included duplex ultrasonography findings on postoperative day 5, bleeding events [defined by International Society on Thrombosis and Hemostasis (ISTH) criteria], Knee Society Score (KSS) at 90 days, and length of stay. Results Among 454 patients included, 44 (9.7%) had an isolated preoperative MCVT. No patients in either group developed symptomatic VTE or pulmonary embolism (0/44 vs. 0/410, 95% CI 0.0%–8.0% and 0.0%–0.9%). Routine duplex ultrasonography on postoperative day 5 showed no thrombus progression or new deep vein thrombosis (DVT) in either group. No ISTH-defined major bleeding or clinically relevant non-major bleeding (CRNMB) occurred. KSS outcomes and length of stay were similar between groups (all P > 0.05). Conclusion Under a protocolized ERAS pathway with combined mechanical prophylaxis and standard chemoprophylaxis, we observed no clinically evident thrombotic or bleeding events within 90 days in patients with asymptomatic isolated preoperative MCVT who proceeded to TKA without delay or preoperative therapeutic-dose anticoagulation. These findings are descriptive and hypothesis-generating and cannot exclude rare but clinically important differences; prospective multicenter studies are needed to quantify rare events and clarify generalizability across thrombus profiles and prophylaxis regimens.