title: The effect of femoral offset modification on gait after total hip arthroplasty.
abstract: OBJECTIVE
  A decrease of 15% in femoral offset (FO) has been reported to generate a weakness of the abductor muscle, but this has not been directly linked to an alteration of gait. Our hypothesis was that this 15% decrease in FO may also generate a clinically detectable alteration in the gait.
  
  
  METHODS
  We performed a prospective comparative study on 28 patients who underwent total hip arthroplasty (THA) for unilateral primary osteoarthritis. The 3D hip anatomy was analyzed preoperatively and postoperatively. 3 groups were defined according to the alteration in FO following surgery: a minimum decrease of 15% (9 patients), restored (14), and a minimum increase of 15% (5). A gait analysis was performed at 1-year follow-up using an ambulatory device. Each limb was compared to the contralateral healthy limb.
  
  
  RESULTS
  In contrast to the "restored" group and the "increased" group, in the "decreased" group there was a statistically significant asymmetry between sides, with reduced range of motion and a lower maximal swing speed on the operated side.
  
  
  CONCLUSIONS
  A decrease in FO of 15% or more after THA leads to an alteration in the gait. We recommend 3-D preoperative planning because the FO may be underestimated by up to 20% on radiographs and it may therefore not be restored, with clinical consequences.
authors.affiliation: Hôpital Pitié Salpétrière , Paris.
authors.forename: Elhadi
authors.initials: E
authors.lastname: Sariali
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Klouche
authors.forename: Alexandre
authors.initials: A
authors.lastname: Mouttet
authors.forename: Hugues
authors.initials: H
authors.lastname: Pascal-Moussellard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005684:Gait; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011446:Prospective Studies; D016059:Range of Motion, Articular; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome