title: Minimizing bone gaps when using custom pediatric cranial implants is associated with implant success.
abstract: OBJECTIVE
  Occasionally after a craniotomy, the bone flap is discarded (as in the case of osteomyelitis) or is resorbed (especially after trauma), and an artificial implant must be inserted in a delayed fashion. Polyetheretherketone (PEEK) implants and hard-tissue replacement patient-matched implants (HTR-PMI) are both commonly used in such cases. This study sought to compare the failure rate of these 2 implants and identify risk factors of artificial implant failure in pediatric patients.
  
  
  METHODS
  This was a retrospective cohort study examining all pediatric patients who received PEEK or HTR-PMI cranioplasty implants from 2000 to 2013 at a single institution. The authors examined the following variables: age, sex, race, mechanism, surgeon, posttraumatic hydrocephalus, time to cranioplasty, bone gap width, and implant type. The primary outcome of interest was implant failure, defined as subsequent removal and replacement of the implant. These variables were analyzed in a bivariate statistical fashion and in a multivariate logistic regression model for the significant variables.
  
  
  RESULTS
  The authors found that 78.3% (54/69) of implants were successful. The mean patient age was 8.2 years, and a majority of patients were male (73%, 50/69); the mean follow-up for the cohort was 33.3 months. The success rate of the 41 HTR-PMI implants was 78.1%, and the success rate of the 28 PEEK implants was 78.6% (p = 0.96). Implants with a bone gap of > 6 mm were successful in 33.3% of cases, whereas implants with a gap of < 6 mm had a success rate of 82.5% (p = 0.02). In a multivariate model with custom-type implants, previous failed custom cranial implants, time elapsed from previous cranioplasty attempt, and bone gap size, the only independent risk factor for implant failure was a bone gap > 6 mm (odds ratio 8.3, 95% confidence interval 1.2-55.9).
  
  
  CONCLUSIONS
  PEEK and HTR-PMI implants appear to be equally successful when custom implantation is required. A bone gap of > 6 mm with a custom implant in children results in significantly higher artificial implant failure.
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Bowers
authors.affiliation: Plastic and Reconstructive Surgery, Primary Children's Medical Center, University of Utah; and.
authors.forename: Jaron H
authors.initials: JH
authors.lastname: McMullin
authors.affiliation: University of Utah School of Medicine, Salt Lake City, Utah.
authors.forename: Cameron
authors.initials: C
authors.lastname: Brimley
authors.affiliation: Plastic and Reconstructive Surgery, Primary Children's Medical Center, University of Utah; and.
authors.forename: Linsey
authors.initials: L
authors.lastname: Etherington
authors.affiliation: Plastic and Reconstructive Surgery, Primary Children's Medical Center, University of Utah; and.
authors.forename: Faizi A
authors.initials: FA
authors.lastname: Siddiqi
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Jay
authors.initials: J
authors.lastname: Riva-Cambrin
mesh_terms: D000367:Age Factors; D001577:Benzophenones; D001672:Biocompatible Materials; D001705:Bioprosthesis; D002508:Cephalometry; D003399:Craniotomy; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006849:Hydrocephalus / Q000601:surgery; D007659:Ketones; D008297:Male; D016348:Osseointegration; D011092:Polyethylene Glycols; D011108:Polymers; D011183:Postoperative Complications / Q000601:surgery*; D019736:Prostheses and Implants / Q000009:adverse effects; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012886:Skull / Q000473:pathology / Q000601:surgery*; D013524:Surgical Flaps; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols
keywords: CI = confidence interval; HTR-PMI = hard-tissue replacement patient-matched implant; PEEK = polyetheretherketone; cranioplasty; custom cranial implants; failure rates