title: The effect of increased hip flexion using stirrups on lower-extremity venous flow: a prospective observational study.
abstract: 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.
authors.affiliation: Section of Plastic Surgery, University of Michigan, Ann Arbor, 48105, USA. cpannucc@umich.edu
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pannucci
authors.forename: Peter K
authors.initials: PK
authors.lastname: Henke
authors.forename: Paul S
authors.initials: PS
authors.lastname: Cederna
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Strachn
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Brown
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Moote
authors.forename: Darrell A
authors.initials: DA
authors.lastname: Campbell
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D015179:Colorectal Neoplasms / Q000601:surgery*; D005268:Femoral Vein / Q000000981:diagnostic imaging*; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D018616:Ultrasonography, Doppler, Duplex; D020246:Venous Thrombosis / Q000209:etiology / Q000517:prevention & control*; D055815:Young Adult