title: Hydraulic resistance: a measure of vascular outflow obstruction in osteonecrosis.
abstract: This study introduces hydraulic resistance (HR) as a new method to measure intraosseous vascular outflow resistance in the human proximal femur. HR is the standard measure of resistance to fluid flow in porous matrices and is derived from serial pressure/flow determinations. Eighteen hips were studied in 11 patients taken to surgery for core decompression therapy of presumable atraumatic osteonecrosis of the femoral head. HR was much higher in osteonecrotic (174 +/- 29 mm Hg min/ml, SE) than in normal human cadaveric femora (14 +/- 6) and was also higher in subcapital (253 +/- 39) than intertrochanteric sites (78 +/- 17). HR correlated highly with baseline intraosseous pressure (r = 0.74, p less than 0.001). HR testing is a simple, practical method which quantifies outflow obstruction of the intraosseous circulation. We believe this test will be helpful in the diagnosis of atraumatic osteonecrosis and in the understanding of its underlying pathophysiology.
authors.affiliation: Department of Medicine, University of Washington, Seattle 98195.
authors.forename: D J
authors.initials: DJ
authors.lastname: Downey
authors.forename: P A
authors.initials: PA
authors.lastname: Simkin
authors.forename: W L
authors.initials: WL
authors.lastname: Lanzer
authors.forename: F A
authors.initials: FA
authors.lastname: Matsen
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001783:Blood Flow Velocity; D004285:Dogs; D005270:Femur Head / Q000098:blood supply / Q000473:pathology; D005271:Femur Head Necrosis / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D005272:Femur Neck / Q000098:blood supply / Q000473:pathology; D006801:Humans; D007432:Intraoperative Period; D008722:Methods; D008875:Middle Aged; D014159:Transducers; D014655:Vascular Resistance