title: U-shaped sacral fracture with iliac crest apophyseal avulsion in a young child.
abstract: BACKGROUND
  U-shaped sacral fractures or Jumper's fractures are rare injuries in adults and are even rarer in the pediatric population. These fractures share a common pathoanatomy where the pelvis as a unit together with the bilateral alar parts and the lower part of the sacrum, loses its skeletal and soft tissue connections to the remaining axial skeleton and hence the term spinopelvic dissociation. This report describes an unusual pattern of spinopelvic dissociation in a young child where the transverse process of the fifth lumbar vertebra was avulsed on one side (spinal side avulsion), whereas on the other side, complete iliac crest apophyseal avulsion took place (pelvic sided avulsion). To our knowledge, this combination of injuries was not reported before. The available literature describing pediatric U-shaped sacral fractures were also reviewed to help explain the pathoanatomic basis of this association.
  
  
  METHODS
  An 8-year-old boy sustained a U-shaped sacral fracture with avulsion of the left iliac crest apophysis. A search in the English literature was performed for all reports of U-shaped sacral fractures in pediatric patients (≤ 18 y of age), as well as the relevant literature, which describes the pathoanatomy, possible radiologic findings, and current classification systems and treatment options.
  
  
  RESULTS
  Fixation using a 7.3 mm percutaneous iliosacral screw was performed. At the latest follow-up, the child had no pain, was fully bearing weight on lower extremities, and was neurologically intact. The literature review yielded 6 other pediatric patients with U-shaped sacral fractures in 4 articles.
  
  
  CONCLUSIONS
  In young children with immature pelvis, the iliac apophysis may be avulsed instead of the transverse process of the fifth lumbar vertebra by forces transmitted through the iliolumbar ligament. The apophysis will therefore keep its attachment to the abdominal and trunk muscles, whereas the bony iliac wing and the pelvis would be dissociated from the axial skeleton. Otherwise, the pathoanatomy of these injuries is the same as described in adults.
  
  
  METHODS
  Level IV.
authors: Orthopaedic Department, Faculty of Medicine, Sohag University, Sohag, Egypt.
authors: Mohamed
authors: M
authors: Kenawey
authors: Ahmad
authors: A
authors: Addosooki
mesh_terms: D001863:Bone Screws; D002648:Child; D005593:Fracture Fixation, Internal; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D008297:Male; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed