Does Autologous vs. Alloplastic Cranioplasty Affect Cranial Growth Patterns?

Background:

While cranioplastic reconstructive strategies in adults include autologous bone grafts, bone substitutes, and alloplastic materials, there remains a hesitation to reconstruct pediatric cranial defects with synthetic material when paucity of autologous bone graft exists. Pediatric cranioplasty incurs challenges of increased bone resorption, timing, cranial growth, limited donor allograft, and longer exposure to foreign materials as a nidus for infection. Effect on cranial growth after cranioplasty in children is not fully elucidated. Herein, we review the cranial growth of pediatric patients who underwent cranioplasty at our institution. 

Methods:

After IRB approval, a retrospective single institution review was conducted from a database of pediatric patients who underwent cranioplasty from 2000 to 2017. Patients without pre-operative, short-term (< 3 months) post-operative, and long-term (>11 months) post-operative imaging were excluded. Patients were divided into alloplastic vs. autologous reconstruction cohorts. Demographics, co-morbidities, age at surgery, etiology and size of cranial defect, type of reconstruction, time of initial surgery to reconstruction, and complications were assessed. 3D surface models were created from CT data and set to the Frankfort horizontal line, which allowed for calculation of cephalometrics pre and post-operatively including cranial growth. These cohorts were then compared to an age-specific database of 3D cranial imaging in normal subjects for assessment of growth patterns.¹ Statistical analysis was performed using SPSS version 22.0. 

Results:

Thirty-two patients met inclusion criteria for reconstructive cranioplasty (8 mos – 18 years, mean 9.6 years). Cephalic length, width, and 3D measurements were obtained to calculate the cephalic index at varying time points. Etiology of cranial defects included trauma (50%), neoplasm (12.5%), cerebral vascular accident (12.5%), epilepsy (9%), congenital cranial defect (9%), and herniation (4%). Twenty-three patients underwent autologous bone flap reconstruction, 7 underwent alloplastic reconstruction, and 2 underwent a combination of both. In long-term follow up, 3 alloplastic implants were lost to infection. Five autologous bone flaps were lost to infection and replaced with alloplastic materials. An additional 3 autologous bone flaps were revised due to nonunion or resorption. A total of 8 autologous and 3 alloplastic cranioplasties failed respectively. Cranial index at pre-operative, post-operative, and long-term follow up did not significantly differ between autologous vs. alloplastic cranioplasties at each age group (p= 0.05 – 0.89) (Figure 1). When compared to normative CI means, there was also no significant difference at each age group (p=0.08-0.99).

Conclusion:

Both autologous and alloplastic cranioplasty do not appear to affect cranial growth patterns in children as compared to normative data. There was a higher failure rate in autologous cranioplasty compared to alloplastic cranioplasty. There does not appear to be a significant difference in cranial growth between autologous and alloplastic cranioplasty.

  

References:

 

1. Delye H, Clijmans T, Mommaerts MY, Sloten JV, Goffin J. Creating a normative database of age-specific 3D geometrical data, bone density, and bone thickness of the developing skull: a pilot study. J Neurosurg Pediatr 16:687–702, 2015