The combined use of hydroxyapatite and bioresorbable plates to repair cranial defects in children

Abstract

Object. Hydroxyapatite cement (HAC) is used with increasing frequency by craniofacial surgeons for building facial and skull base structures and by neurosurgeons for cranioplasty. Failures of HAC in cranioplasty have been attributed to breakage due to subjacent cerebrospinal fluid (CSF) pulsations through the dura mater. The authors describe a technique that involves inserting a resorbable MacroPore perforated plate to dampen CSF pulsations and then pouring HAC over the plate to fill a cranial defect and complete skull contouring. Methods. Fifteen children ranging in age from 2 to 9.5 years were included in the study; the size of the skull defects in these patients ranged from 6.25 to 42.5 cm2, with a mean of 20.65 cm2. Patients in whom the combined MacroPore-HAC devices were implanted underwent follow-up examinations that included serial skull radiography and computerized tomography scans. No fractures of the implants were demonstrated. At 6 months postsurgery, small fingerlings of new bone growth appeared in the underside of the HAC plate, probably spanning from the dura through perforations in the MacroPore plate. At intervals ranging from 18 months to 20 years after implantation, the gaps between cranial bone edges and that the HAC began to blur, culminating in the complete bonding of host bone with the margin of the HAC plate. All implants remained radiopaque and maintained size, thickness, and shape. Conclusions. The findings of this study are promising and indicate that the combined use of HAC and a bioresorbable undercarriage that is osteoconductive, such as the MacroPore perforated plate, may produce a versatile and lasting cranioplasty in children.