title: Comparison of femoral head translation following eccentric rotational acetabular osteotomy and rotational acetabular osteotomy.
abstract: OBJECTIVE
  Eccentric rotational acetabular osteotomy (ERAO) is a modification of rotational acetabular osteotomy (RAO); it has been reported that ERAO allows the femoral head to translate medially and distally. However, no study has compared femoral head translation following RAO or ERAO. The purpose of this study was to compare immediate postoperative translation of the femoral head after RAO and ERAO in comparison with the preoperative position by radiological methods.
  
  
  METHODS
  Patients treated by RAO or ERAO between 2006 and 2014 were retrospectively evaluated. 19 hips (17 patients) were treated with RAO, and 25 hips (22 patients) were treated with ERAO. The acetabular roof angle and the location of the femoral head were measured on anteroposterior pelvic radiographs.
  
  
  RESULTS
  The mean preoperative acetabular roof angle was 20.9° in the RAO group and 22.0° in the ERAO group, showing no significant difference. The mean acetabular roof angle immediately postoperatively was -0.5° in the RAO group and -0.4° in the ERAO group, again showing no significant difference. The mean femoral head translation immediately postoperatively was 3.1 mm (95% confidence interval (CI), 1.5-4.7 mm) laterally and 3.0 mm (95% CI, 1.3-4.7 mm) proximally in the RAO group and 0.8 mm (95% CI, -0.7-2.3 mm) medially and 2.8 mm (95% CI, 1.5-4.1 mm) distally in the ERAO group; this difference was very highly significant (p<0.001).
  
  
  CONCLUSIONS
  In contrast with RAO, ERAO resulted in significant femoral head translation both medially and distally immediately postoperatively.
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Tohru
authors: T
authors: Irie
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Daisuke
authors: D
authors: Takahashi
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Tsuyoshi
authors: T
authors: Asano
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Ryuta
authors: R
authors: Arai
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Takuya
authors: T
authors: Konno
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Tomohiro
authors: T
authors: Onodera
authors:  Department of Advanced Therapeutic Research for Sports Medicine, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Eiji
authors: E
authors: Kondo
authors:  Department of Orthopedic Surgery, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo - Japan.
authors: Norimasa
authors: N
authors: Iwasaki
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000601:surgery*; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000209:etiology / Q000517:prevention & control*; D010027:Osteotomy / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D012189:Retrospective Studies; D018570:Risk Assessment; D012399:Rotation; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult