Related Experiment Video
Updated: May 30, 2026

Doppler Ultrasound-Based Leg Blood Flow Assessment During Single-Leg Knee-Extensor Exercise in an Uncontrolled Setting
Published on: December 15, 2023
The effect of increased hip flexion using stirrups on lower-extremity venous flow: a prospective observational study
Christopher J Pannucci1, Peter K Henke, Paul S Cederna
1Section of Plastic Surgery, University of Michigan, Ann Arbor, 48105, USA. cpannucc@umich.edu
Background:
Patient positioning during surgeries for colorectal cancer may represent an unrecognized risk factor for deep venous thrombosis.
Methods:
Twelve healthy control patients were positioned supine with knee flexion at 90°. Duplex ultrasound examined common femoral vein (CFV) and proximal femoral vein diameter, peak systolic velocity, and volume flow with hip flexion at 0°, 30°, 60°, and 90°. Data were analyzed using the paired t test.
Results:
In the CFV, hip flexion to 90° was associated with a significant increase in mean volume flow when compared with hip flexion at 0° (.59 vs .36 L/min; P = .05) and 30° (.59 vs .35 L/min; P = .038). In both the CFV and proximal femoral vein, increased hip flexion was associated with significantly reduced vessel diameter and increased peak systolic velocity.
Conclusions:
Intraoperative positioning of the lower extremities represents a modifiable risk factor for deep venous thrombosis. When stirrups are used, hip flexion of 90° maximizes venous drainage from the legs.
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