title: Articular surface remodeling of the hip after periacetabular osteotomy.
abstract: OBJECTIVE
  Periacetabular osteotomies are a family of surgical procedures used to treat hip dysplasia. In a periacetabular osteotomy, the operating surgeon aims to increase acetabular coverage of the femoral head. The surgical correction has mechanical goals of increasing the stability of the joint and to improving the pressure distribution across the acetabulum. Although it is known that bone will remodel under changing load at the microstructural level, it is unclear whether there is any gross remodeling of the acetabulum or the femoral head in response to the change in loading following a periacetabular osteotomy. This observational study aims to quantify the shape of operative and contralateral hip joint surfaces pre and postoperatively to determine whether there are gross morphological changes in the shape of any of the bony articular surfaces of the joint.
  
  
  METHODS
  Preoperative and postoperative computed tomography (CT) scans were segmented as triangulated meshes. The bony articular surfaces of these meshes were then isolated. The vertices of these surfaces were fit to spheres and to general ellipsoids and, in the case of the acetabulum, examined in anatomical coordinate frames to look for changes between pre and postoperative segmentations.
  
  
  RESULTS
  Spherical fit results were consistent preoperatively and postoperatively, with small changes in the radii of the spheres of best fit for both operative and nonoperative hips. Ellipsoid fitting showed variations between preoperative and postoperative scans in both eccentricity and orientation.
  
  
  CONCLUSIONS
  Because there is no clear evidence of gross articular surface remodeling, periacetabular osteotomy for an adult should be planned with the expectation that the patient's existing articular structure will be preserved.
authors: Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada. brian.rasquinha@queensu.ca
authors: Brian J
authors: BJ
authors: Rasquinha
authors: Junaid
authors: J
authors: Sayani
authors: John F
authors: JF
authors: Rudan
authors: Gavin C A
authors: GC
authors: Wood
authors: Randy E
authors: RE
authors: Ellis
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000328:Adult; D000465:Algorithms; D016723:Bone Remodeling / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D018570:Risk Assessment; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome