title: Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty.
abstract: BACKGROUND
  Primary total hip arthroplasty leads to better functional capacities but a general weakness of abductor muscles often persists. A larger head component may improve the postural balance in the medial-lateral direction. The aims of this study are (1) to compare postural stability in patients after total hip and surface replacement arthroplasties and (2) to evaluate the effect of the biomechanical reconstruction on postural stability.
  
  
  METHODS
  Six months post-surgery, three groups of ten subjects (total hip and surface replacement arthroplasties and control) performed quiet standing tasks in both dual and one leg stance and a hip abductor muscles strength test. The root-mean-square amplitude of centre of pressure and centre of mass displacement in the anterior-posterior and medial-lateral directions were calculated for dual stance task.
  
  
  RESULTS
  Statistical analyses showed greater centre of pressure and centre of mass displacement amplitude in the medial-lateral direction during the dual stance for the total hip arthroplasty compared to the surface replacement and control subjects (P<0.05). All control subjects completed the one leg stance compared to nine in the surface replacement and five in the total hip arthroplasty group. No statistical difference was found between the groups in the hip abductor muscles strength.
  
  
  CONCLUSIONS
  The better anatomical preservation, absence of femoral stem and the larger bearing component could account for the return to better postural stability in surface replacement patients in comparison to total hip patients. Further studies are needed to determine the impact of each of these factors on the postural balance.
authors: Department of Kinesiology, University of Montreal, CP 6128 Centre Ville, Montreal, Canada.
authors: Julie
authors: J
authors: Nantel
authors: Nicolas
authors: N
authors: Termoz
authors: Hugo
authors: H
authors: Centomo
authors: Martin
authors: M
authors: Lavigne
authors: Pascal-André
authors: PA
authors: Vendittoli
authors: François
authors: F
authors: Prince
mesh_terms: D000328:Adult; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods* / Q000534:rehabilitation*; D019544:Equipment Failure Analysis; D005260:Female; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000503:physiopathology; D004856:Postural Balance; D011187:Posture; D011312:Pressure; D011474:Prosthesis Design