title: Pelvic tilt and movement during total hip arthroplasty in the lateral decubitus position.
abstract: OBJECTIVE
  Total hip arthroplasty (THA) is often performed in the lateral decubitus (lateral) position. In this position, the pelvis may have various degrees of tilt leading to implant malposition. We sought to quantify the pelvic tilt in lateral position and further pelvic movement during surgery.
  
  
  METHODS
  In 95 cases with primary THA, three-dimensional pelvic tilts were quantified by superimposing images reconstructed from CT data onto antero-posterior radiographs taken in lateral position at set-up and after cup placement. Pelvises were fixed with a device compressing anterior superior iliac spines and sacrum.
  
  
  RESULTS
  Various degrees of pelvic tilt occurred compared to the supine position; sagittal: -3.1° (-25.5° to 10.2°), axial: 3.9° (-8.4° to 17°), coronal: 0.9° (-11.9° to 13.2°). Absolute changes more than 5° were observed 43%, 47%, and 12% in the sagittal, axial, and coronal planes, respectively. The more preoperative posterior pelvic tilt resulted in the more change in the sagittal plane. Further pelvic movement of about 3° in three planes were observed ranging from -11° to 20° after cup placement.
  
  
  CONCLUSIONS
  This study showed various pelvic tilt and movement during THA. As pelvic tilt directly alters the cup orientation, its changes should be well understood. Improved tools for positioning and holding the pelvis are required.
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanazawa
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Ohishi
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hamai
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Fukushi
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ushijima
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hara
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Higashi-Ku , Fukuoka , Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D010388:Pelvis; D011187:Posture
keywords: Lateral decubitus position; Pelvic movement; Pelvic tilt; Total hip arthroplasty