Hydroxyapatite cement in craniofacial skeletal reconstruction and its effects on the developing craniofacial skeleton.

OBJECTIVE To assess the effects of hydroxyapatite cement (HAC) on the developing feline craniofacial skeleton. DESIGN Fronto-orbital craniotomies were performed on 14 kittens and reconstructed by autograft or HAC. By design, animals in which the craniofacial skeleton was reconstructed 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 caliper. Additional analyses included histological studies, histomorphometry, and computed tomography. SUBJECTS Twenty-one 12-week-old female cats were divided into 3 groups, composed of 7 specimens. INTERVENTION 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 with no evidence of wound infection or implant failure. Gross morphological studies demonstrated excellent contour reconstruction in both experimental 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 with obliteration of the left frontal sinus in group 3. Histological studies showed that HAC was osseointegrated to native bone, with areas of new bone interspersed throughout the implants. No significant inflammatory response or fibrous encapsulation was noted. Histomorphometry demonstrated that implants were replaced by osseous tissue in 44% to 50% of the animals within 5 months. CONCLUSION Hydroxyapatite cement is safe and effective for craniofacial reconstruction in the developing feline and may be appropriate for similar applications in humans.