title: Can neonatal pelvic osteotomies permanently change pelvic shape in patients with exstrophy? Understanding late rediastasis.
abstract: BACKGROUND
  Pelvic osteotomies are frequently used as part of the surgical management of bladder exstrophy. The outcomes are often measured on the basis of the residual symphyseal diastasis. The aims of this study were to evaluate and validate a more reliable radiographic measure of ischiopubic rotation, to utilize this measure in analyzing pelves from patients with exstrophy and controls, and to propose a model for rediastasis in a pelvis with exstrophy.
  
  
  METHODS
  Pelvic radiographs of 164 normal children two months to eighteen years of age were used to determine the changes in interpubic and interischial distances and in the interischial/interpubic (IS/IP) ratio with age. Twenty-one pelvic CT (computed tomography) studies of normal children, two to sixteen years of age, were also used to study the change in the ischiopubic divergence angle. The same parameters were measured on radiographs or CT or magnetic resonance imaging studies of seventy-three patients with classic bladder exstrophy who were followed for two to nineteen years after exstrophy closure with or without pelvic osteotomies.
  
  
  RESULTS
  In normal children, the interpubic distance and the ischiopubic divergence angle had a narrow range and were constant with age, whereas the interischial distance and the IS/IP ratio increased progressively and were strongly correlated with age. In the patients with exstrophy, the interpubic distance was positively correlated with the interischial distance, whereas the IS/IP ratio was lower than that in normal controls and was not correlated with age.
  
  
  CONCLUSIONS
  The IS/IP ratio is a useful measure of ischiopubic rotation and can be used to characterize pelvic growth, including the phenomenon of rediastasis in patients with exstrophy. Pelvic rediastasis is a progressive increase in interpubic distance resulting from growth without loss of rotational correction, as shown by the constancy of the IS/IP ratio with age in these patients. A better rotational position at the time of osteotomy may lead to a better pelvic shape at maturity.
  
  
  CONCLUSIONS
  Symphyseal rediastasis following neonatal pelvic osteotomies in patients with exstrophy is not due to loss of correction and progressive derotation of the hemipelves but is a consequence of the normal three-dimensional growth of the pelvis. The best correction of the pelvic deformity should always be the aim even in neonatal pelvic osteotomies because this will permanently change the pelvic shape.
authors.affiliation: Department of Orthopaedic Surgery, Sohag University, Sohag 82524, Egypt. E-mail address: mohamed.kenawey@gmail.com.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Kenawey
authors.affiliation: Division of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: James G
authors.initials: JG
authors.lastname: Wright
authors.affiliation: Division of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: Sevan
authors.initials: S
authors.lastname: Hopyan
authors.affiliation: Division of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: Michael Lucas
authors.initials: ML
authors.lastname: Murnaghan
authors.affiliation: Division of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Howard
authors.affiliation: Division of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Kelley
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001746:Bladder Exstrophy / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010027:Osteotomy / Q000379:methods*; D010384:Pelvic Bones / Q000254:growth & development* / Q000601:surgery; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014102:Torsion Abnormality / Q000473:pathology / Q000503:physiopathology