title: Obese patients may have more soft tissue impingement following primary total hip arthroplasty.
abstract: OBJECTIVE
  Several studies have reported a risk of dislocation in obese patients after total hip arthroplasty. In this study, we evaluated the interaction between obesity and dislocation by kinematic analysis using a navigation system.
  
  
  METHODS
  The intraoperative range of motion (ROM) and postoperative impingement-free ROM were measured in 38 patients, and we compared the impingement-free ROM in obese and non obese patients.
  
  
  RESULTS
  The postoperatively simulated ROM was similar in the obese and non obese groups. The intraoperative ROM was smaller in the obese group. The difference values between the intraoperative ROM and postoperatively simulated ROM were larger in the obese group. These results indicate that obese patients have less ROM following primary total hip arthroplasty even when the implant positioning is performed correctly.
  
  
  CONCLUSIONS
  Dislocations are multifactorial problems including soft tissue impingement. Therefore, the risk of dislocation caused by soft tissue impingement in obese patients may be increased.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan. shayashi@med.kobe-u.ac.jp
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nishiyama
authors.forename: Takaaki
authors.initials: T
authors.lastname: Fujishiro
authors.forename: Shingo
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kanzaki
authors.forename: Kotaro
authors.initials: K
authors.lastname: Nishida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D057925:Femoracetabular Impingement / Q000453:epidemiology*; D006621:Hip Joint / Q000502:physiology / Q000601:surgery; D006801:Humans; D004204:Joint Dislocations / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D025321:Surgery, Computer-Assisted