Preparation of Hydroxyapatite Cement and Analysis as of its Disposition

Objective: To prepare hydroxyapatite cement (or calcium phosphate cement, CPC) and analyze its capability. Methods: Tetracalcium phosphate (TTCP) was prepared by the method of high heat. TTCP reacted with in simulated body situation and produced CPC, Its capability was analyzed by scanning electron microscopy (SEM) , X-ray diffraction(XRD). Its density, absorbing water coefficient, macroporosity and campressive strength were measured also. Results: The main element of CPC is hydroxyapatite (HA) , its microstructure comprised of needlelike or petal crystals. The diameter of micropore was 4-10 nm, density was 1.922 g/cm3, macroporosity was 29. 777% , absorbing coefficient was 15. 503%, compressive strength was 42. 70 Mpa. Conclusion: This CPC has three-dimensional spatial structure, its strength meets the need of cancellous bone grafting.

Drug Release Characteristics of Hydroxyapatite Bone Cement

To discuss the feasibility of bydroxyapatite bone cement （HAC） used as a drug delivery carrier and observe the bacteriostatic activity of HAC/ Norvancomycin（ HAC/ NVCM ） composite in vitro and its release characteristics in vivo. Bacteriostatic zone and cycle of composite containing 1.5wt% of NVCM were measured in vitro studies. In vivo stndies , the composite was implanted into the top of rabbit＇ s tibia as the local medication group, HAC without NVCM being composed was also implanted and NVCM was injected into auricular vein as the systemic medication group. Cnncentrations of NVCM in blood and local bone were measured in both groups at different time points. The experimental results showed that HAC did not influence the bacteriostatic activity of NVCM otviously, and NVCM exist in the porosities of HAC in the pattern of amorphism. The blood coueemrations of NVCM in local medication group were always lower than those in systemic medication group at any time point, while the bone concentrations of NVCM in local medication group were much higher than those of systemic medication group,which remained to be 3.96μg/mg/mL after 2 weeks. And HAC has good release characteristics as a drug delivery earricr.

Reducing the risk of cerebrospinal fluid rhinorrhea following translabyrinthine surgery of the posterior fossa

Objective:To describe the procedure and results of an adapted closure and recon struction technique for translabyrinthine surgery that focuses on identifying and managing potential pathways for CSF egress to the middle ear and Eustachian tube.Methods:Retrospective review of a cohort of translabyrinthine acoustic neuroma cases that were reconstructed using this technique.Results:In addition to meticulous packing of potential conduits using soft tissue,hydroxyapatite cement is used to seal opened air cell tracts prior to obliteration of the mastoid defect using adipose tissue.Early results of a small patient cohort using this technique are encouraging and there were no wound infections.There was a single case of CSF rhinorrhea associated with incomplete sealing of opened petrous apex cells,with no recurrence after appropriate implementation of the described protocol during revision surgery.Conclusion:Proactive management of potential conduits of CSF egress including opened air cell tracts has a high likelihood of reducing rates of rhinorrhea and need for revision surgery after the translabyrinthine approach to the posterior fossa.