title: Three-dimensional kinetic simulation before and after rotational acetabular osteotomy.
abstract: BACKGROUND
  Some reports indicate that one of major causes of clinical failure after periacetabular osteotomy is development of secondary femoroacetabular impingement (FAI). To assess the impact of range of motion (ROM) on the increase in FAI following rotational acetabular osteotomy (RAO), we performed FAI simulations before and after RAO.
  
  
  METHODS
  We evaluated 12 hips that had undergone RAO (study group), and 12 normal hips (control group). The study group was evaluated before and after surgery. Morphological parameters were evaluated to assess acetabular coverage. The acetabular anteversion angle, anterior CE angle, alpha angle, and combined anteversion angle were also measured. Impingement simulations were performed using 3D-CT. The ROM which causes bone-to-bone impingement was evaluated in flexion (flex), abduction, external rotation at 0° flexion, and internal rotation at 90° flexion. The lesions caused by impingement were evaluated.
  
  
  RESULTS
  Radiographic measurements indicated improved postoperative acetabular coverage in the study group. The crossover sign was recognized pre- and postoperatively in every case in the study group and in no cases in the control group. In the simulation study, flexion, abduction, and internal rotation at 90° flexion decreased postoperatively. Impingement occurred within 45° internal rotation at 90° flexion in two preoperative and nine postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. There were correlations between anterior CE angle, CE angle, acetabular anteversion angle, and hip flexion angle. There were also correlations between the anterior CE angle, combined anteversion angle, and angle of internal rotation at 90° flexion.
  
  
  CONCLUSIONS
  In the postoperative simulation, there was a tendency to reduce the ROM in flexion, abduction, and internal rotation at 90° flexion due to impingement. Since there were more cases which caused impingement within 45° internal rotation at 90° flexion after RAO, we consider there is a potential for increased FAI after RAO.
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, 920-8641, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Iwai
authors.forename: Tamon
authors.initials: T
authors.lastname: Kabata
authors.forename: Toru
authors.initials: T
authors.lastname: Maeda
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kajino
authors.forename: Shin
authors.initials: S
authors.lastname: Watanabe
authors.forename: Kazunari
authors.initials: K
authors.lastname: Kuroda
authors.forename: Kenji
authors.initials: K
authors.lastname: Fujita
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000328:Adult; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D016059:Range of Motion, Articular; D012399:Rotation; D014057:Tomography, X-Ray Computed