Icing and multilayering technique of injectable hydroxyapatite cement paste for cranial base reconstruction after transsphenoidal surgery: technical note.

Objective: Injectable hydroxyapatite cement (HAC, Biopex; Mitsubishi Pharma Corp., Osaka, Japan) can reconstruct the accurate contour of bone defects intraoperatively, and it is slowly replaced with bone by a process of resorption and osteoconduction, making it a useful substrate for the repair of cranial defects. In the operative site with continuous oozing of the cerebrospinal fluid, however, the implanted HAC may be dissolved and washed out as a result of its water solubility during the setting time. For successful reconstruction of cranial defects in such wet situations, we describe a new technique to reinforce the implanted HAC with a multilayered application.

Methods: As a preliminary experiment, we observed that the setting process of the HAC was severely restricted by the environmental temperature. At a temperature of 5 degrees C, the initial setting time of the HAC could be extended to 10 hours after the beginning of the mixing of the HAC. Bone defects of the sellar floor after transsphenoidal surgery for pituitary adenomas, craniopharyngiomas, meningiomas, or suprasellar arachnoid cysts were reconstructed using the HAC in 55 patients during a 5-year period. The results and complications were obtained through retrospective review.

Results: Ninety-eight percent of bone defects were successfully repaired using the HAC, and the reconstruction remained stable over the course of this study. There was one case of postoperative cerebrospinal fluid leakage. Wound infection occurred in one patient, which required reoperation and removal of the biomaterial.

Conclusion: The icing and multilayering method for proper use of this biomaterial resulted in restoration of the integrity of the cranial base bone and a decrease of cerebrospinal fluid leakage as a postoperative complication of transsphenoidal surgery. HAC is a biomaterial that is recommended to be used as the primary method for reconstructing cranial base bone defects.