Autologous split calvarium cranioplasty for pediatric skull defect

Abstract

Background: Pediatric skull defects usually close naturally; however, cranioplasty is required in patients in whom adequate closure of defects does not occur. Although alloplastic materials are commonly used for cranioplasty in adults, autologous bone flap cranioplasty is preferred in pediatric patients considering the continued calvarial growth in this patient population. We report split calvarium cranioplasty and its outcomes.

Patients and Methods: We investigated the background and treatment outcomes in 10 patients who underwent split calvarium cranioplasty at our hospital between 2011 and 2018. Briefly, split calvarium cranioplasty was performed as follows: We harvested calvarial bone from an area showing an adequately formed diploic layer on preoperative imaging. Using a bone saw, we split the harvested bone into two layers; the lamina externa was returned to its original position, and the lamina interna was placed in the cranial defect and fixed with absorbable sutures.

Results: The study included 10 patients (6 males and 4 females, aged 5-21 years [mean 12.3 years]). The mean interval between the diagnosis of the cranial defect and cranioplasty was 3.4 years (0-12.5 years), with a mean follow-up period of 2.5 years (0.2-7.8 years). This study included 3 patients with calvarial Langerhans cell histiocytosis, 3 patients with fibrous dysplasia, and one patient each with osteoma, encephalocele, decompressive craniectomy after acute subdural hematoma, and bone resorption after brain tumor resection. The mean maximum diameter of skull defects was 32.2 mm (16.2-65.2 mm). Most recent computed tomography (CT) performed after cranioplasty revealed good bony fusion in all patients, and the mean maximum diameter of the skull defect was 4.0 mm (0.3-9.7 mm). The mean transplanted bone thickness at the time of transplantation was 2.3 mm (1.7-4.6 mm), and the transplanted bone thickness observed on the most recent CT was slightly increased to a mean thickness of 2.6 mm (1.7-5.3 mm). However, no patient showed diploë formation.

Discussion: Although split calvarium cranioplasty is associated with the disadvantage of performing an operation on healthy bone along with an increase in the size of the skin incision, this procedure achieves good bone fusion with a low risk of deformation owing to the use of autologous bone. We recommend split calvarium cranioplasty as preferred treatment for pediatric patients.