HYDROXYAPATITE CEMENT IN CRANIOFACIAL SKELETAL RECONSTRUCTION AND ITSEFFECTS ON THE DEVELOPING CRANIOFACIAL SKELETON

Objective: To assess the effects of hydroxyapatite cement (HAC) on the developing feline craniofacial skeleton. Design: Fronto-orbital crani otomies were performed on 14 kittens and reconstructed by autograft or HAC, By design, animals in which the craniofacial skeleton was recons tructed with HAC also underwent obliteration of the left frontal sinus , After achievement of skeletal maturity, animals were sacrificed and compared by 11 standardized cranial measurements obtained by sliding c aliper. Additional analyses included histological studies, histomorpho metry, and computed tomography. Subjects: Twenty-one 12-week-old femal e cats were divided into 3 groups, composed of 7 specimens. Interventi on: The control animals underwent periosteal elevation alone (group 1) . The remaining animals underwent unilateral fronto-orbital craniotomy and subsequent reconstruction with orthotopic bone flap replacement ( group 2) or HAC (group 3). Results: All animals survived the study wit h no evidence of wound infection or implant failure. Gross morphologic al studies demonstrated excellent contour reconstruction in both exper imental groups. Craniometric analysis detected 1 intergroup difference that consisted of a wider skull in group 3 on the reconstructed side, An intragroup difference in orbital height was also seen in group 3. Computed tomography demonstrated a solid appearance of the implant wit h obliteration of the left frontal sinus in group 3. Histological stud ies showed that HAC was osseointegrated to native bone, with areas of new bone interspersed throughout the implants. No significant inflamma tory response or fibrous encapsulation was noted. Histomorphometry dem onstrated that implants were replaced by osseous tissue in 44% to 50% of the animals within 5 months. Conclusion: Hydroxyapatite cement is s afe and effective for craniofacial reconstruction in the developing fe line and may be appropriate for similar applications in humans.