title: Risk factors and rates of bone flap resorption in pediatric patients after decompressive craniectomy for traumatic brain injury.
abstract: OBJECTIVE
  Decompressive craniectomy with subsequent autologous cranioplasty, or the replacement of the native bone flap, is often used for pediatric patients with traumatic brain injury (TBI) who have a mass lesion and intractable intracranial hypertension. Bone flap resorption is common after bone flap replacement, necessitating additional surgery. The authors reviewed their large database of pediatric patients with TBI who underwent decompressive craniectomy followed by bone flap replacement to determine the rate of bone flap resorption and identify associated risk factors.
  
  
  METHODS
  A retrospective cohort chart review was performed to identify long-term survivors who underwent decompressive craniectomy for severe TBI with bone flap replacement from January 1, 1996, to December 31, 2011. The risk factors investigated in a univariate statistical analysis were age, sex, underlying parenchymal contusion, Glasgow Coma Scale score on arrival, comminuted skull fracture, posttraumatic hydrocephalus, bone flap wound infection, and freezer time (the amount of time the bone flap was stored in the freezer before replacement). A multivariate logistic regression model was then used to determine which of these were independent risk factors for bone flap resorption.
  
  
  RESULTS
  Bone flap replacement was performed at an average of 2.1 months after decompressive craniectomy. Of the 54 patients identified (35 boys, 19 girls; mean age 6.2 years), 27 (50.0%) experienced bone flap resorption after an average of 4.8 months. Underlying parenchymal contusion, comminuted skull fracture, age ≤ 2.5 years, and posttraumatic hydrocephalus were significant, or nearly significant, on univariate analysis. Multivariate analysis identified underlying contusion (p = 0.004, OR 34.4, 95% CI 3.0-392.7), comminuted skull fractures (p = 0.046, OR 8.5, 95% CI 1.0-69.6), posttraumatic hydrocephalus (p = 0.005, OR 35.9, 95% CI 2.9-436.6), and age ≤ 2.5 years old (p = 0.01, OR 23.1, 95% CI 2.1-257.7) as independent risk factors for bone flap resorption.
  
  
  CONCLUSIONS
  After decompressive craniectomy for pediatric TBI, half of the patients (50%) who underwent bone flap replacement experienced resorption. Multivariate analysis indicated young age (≤ 2.5 years), hydrocephalus, underlying contusion as opposed to a hemispheric acute subdural hematoma, and a comminuted skull fracture were all independent risk factors for bone flap resorption. Freezer time was not found to be associated with bone flap resorption.
authors.affiliation: Department of Neurosurgery, Primary Children's Medical Center, University of Utah, Salt Lake City, Utah 84113-1100, USA.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Bowers
authors.forename: Jay
authors.initials: J
authors.lastname: Riva-Cambrin
authors.forename: Dean A
authors.initials: DA
authors.lastname: Hertzler
authors.forename: Marion L
authors.initials: ML
authors.lastname: Walker
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D001862:Bone Resorption / Q000209:etiology*; D001930:Brain Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D003288:Contusions / Q000150:complications / Q000209:etiology; D015925:Cryopreservation; D056424:Decompressive Craniectomy / Q000379:methods*; D005260:Female; D018460:Fractures, Comminuted / Q000150:complications / Q000209:etiology; D015600:Glasgow Coma Scale; D006408:Hematoma, Subdural / Q000150:complications / Q000209:etiology / Q000601:surgery*; D006801:Humans; D006849:Hydrocephalus / Q000150:complications / Q000209:etiology; D016015:Logistic Models; D008297:Male; D008499:Medical Records; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D018401:Sample Size; D012737:Sex Factors; D012887:Skull Fractures / Q000150:complications / Q000209:etiology; D013524:Surgical Flaps; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome