Enhanced Biocompatibility and Osseointegration of Calcium Titanate Coating on Titanium Screws in Rabbit Femur / 华中科技大学学报（医学）（英德文版）

This study aimed to examine the biocompatibility of calcium titanate (CaTiO3) coating prepared by a simplified technique in an attempt to assess the potential of CaTiO3 coating as an alternative to current implant coating materials.CaTiO3-coated titanium screws were implanted with hydroxyapatite (HA)-coated or uncoated titanium screws into medial and lateral femoral condyles of 48 New Zealand white rabbits.Imaging,histomorphometric and biomechanical analyses were employed to evaluate the osseointegration and biocompatibility 12 weeks after the implantation.Histology and scanning electron microscopy revealed that bone tissues surrounding the screws coated with CaTiO3 were fully regenerated and they were also.well integrated with the screws.An interfacial fibrous membrane layer,which was found in the HA coating group,was not noticeable between the bone tissues and CaTiO3-coated screws.X-ray imaging analysis showed in the CaTiO3 coating group,there was a dense and tight binding between implants and the bone tissues;no radiation translucent zone was found surrounding the implants as well as no detachment of the coating and femoral condyle fracture.In contrast,uncoated screws exhibited a fibrous membrane layer,as evidenced by the detection of a radiation translucent zone between the implants and the bone tissues.Additionally,biomechanical testing revealed that the binding strength of CaTiO3 coating with bone tissues was significantly higher than that of uncoated titanium screws,and was comparable to that of HA coating.The study demonstrated that CaTiO3 coating in situ to titanium screws possesses great biocompatibility and osseointegration comparable to HA coating.

Mechanical properties, fluorine release behavior and bacterial inhibition of hydroxyapatite-glass ionomer cement / 实用口腔医学杂志

Objective:To investigate mechanical properties,fluorine release behavior and bacteria inhibition effect of hydroxyapatite-improved glass ionomer cement(HA/GIC).Methods:HA/GIC was prepared with HA mass fraction of 28％.Bending strength and compressive strength of HA/GIC and GIC were measured by an universal material testing machine.Microstructure of the materials was observed by scanning microscope technique (SEM).Accumulation of fluorine release was measured by fluorine ion selective electrode.Bacterial inhibition of total bacteria and Streptococcus mutans was monitored by fluorescence in situ hybridization.Results:Bending strength,compressive strength and fluorine release accumulation of HA/GIC were significantly higher than those of GIC (P ＜ 0.05).There were many.irregular polymerized particle monomers and micro cracks within the GIC.In HA/GIC,hydroxyapatite particles were connected with original composition.Bacterial inhibition of total bacteria and Streptococcus mutans by HA/GIC was more effective than that by GIC.Conclusion:HA/GIC has perfect mechanical properties,fluorine release behavior and bacterial inhibition effect.

Development and Perspective of Biomaterials for Spinal Fusion

In this article, research trend of biomaterials for spinal fusion was summarized with an emphasis on hydroxyapatite (HA), titanium(Ti), and polyetheretherketone (PEEK) as representatives of ceramics, metals, and polymers, respectively. Ceramic materials represented by HA are highly biocompatible but have low strength and fracture toughness, so there has been much effort to improve these mechanical properties. Metals such as titanium, Ti, are mechanically strong but have a drawback of stress shielding effect, which can be avoided by fabricating into porous body. Also there have been many researches to improve the biocompatibility of PEEK, which has been widely used recently as a substitute to Ti.

Osteogenic differentiation of bone marrow derived stem cells in gelatin-hydroxyapatite nanocomposite

PURPOSE: Gelatin-hydroxyapatite nanocomposite is similar to inorganic nanostructure of bone. To make a scaffold with osteoinductivity, bone marrow derived stem cells from rabbit femur were impinged into the nanocomposite. This vitro study was to test osteogenic differentiation of the stem cells in the nanocomposite, which was made by authors. MATERIAL & METHODS: Gel-HA nanocomposite with 10g of HA, 3 g of Gel has been made by co-precipitation process. Bone marrow was obtained from femur of New Zealand White rabbits and osteogenic differentiation was induced by culturing of the BMSCs in an osteogenic medium. The BMSCs were seeded into the Gel-HA nanocomposite scaffold using a stirring seeding method. The scaffolds with the cells were examined by scanning electron microscopy (SEM), colorimetry assay, biochemical assay with alkaline phosphatase (ALP) diagnostic kit, osteocalcin ELISA kit. RESULTS: Gel-HA nanocomposite scaffolds were fabricated with relatively homogenous microscale pores (20-40 micrometer). The BMSCs were obtained from bone marrow of rabbit femurs and confirmed with flow cytometry, Alizarin red staining. Attachment and proliferation of BMSCs in Gel-HA nanocomposite scaffold could be identified by SEM, ALP activity and osteocalcin content of BMSCs. CONCLUSION: The Gel-HA nanocomposite scaffold with micropores could be fabricated and could support BMSCs seeding, osteogenic differentiation.

Osteogenic differentiation of bone marrow derived stem cells in gelatin-hydroxyapatite nanocomposite

PURPOSE: Gelatin-hydroxyapatite nanocomposite is similar to inorganic nanostructure of bone. To make a scaffold with osteoinductivity, bone marrow derived stem cells from rabbit femur were impinged into the nanocomposite. This vitro study was to test osteogenic differentiation of the stem cells in the nanocomposite, which was made by authors. MATERIAL & METHODS: Gel-HA nanocomposite with 10g of HA, 3 g of Gel has been made by co-precipitation process. Bone marrow was obtained from femur of New Zealand White rabbits and osteogenic differentiation was induced by culturing of the BMSCs in an osteogenic medium. The BMSCs were seeded into the Gel-HA nanocomposite scaffold using a stirring seeding method. The scaffolds with the cells were examined by scanning electron microscopy (SEM), colorimetry assay, biochemical assay with alkaline phosphatase (ALP) diagnostic kit, osteocalcin ELISA kit. RESULTS: Gel-HA nanocomposite scaffolds were fabricated with relatively homogenous microscale pores (20-40 micrometer). The BMSCs were obtained from bone marrow of rabbit femurs and confirmed with flow cytometry, Alizarin red staining. Attachment and proliferation of BMSCs in Gel-HA nanocomposite scaffold could be identified by SEM, ALP activity and osteocalcin content of BMSCs. CONCLUSION: The Gel-HA nanocomposite scaffold with micropores could be fabricated and could support BMSCs seeding, osteogenic differentiation.

Mid-term follow-ups of hydroxyapatite extensively-coated femoral prosthesis for elderly patients / 中华创伤骨科杂志

Objective To evaluate the effects of hydroxyapatite (HA) extensively-coated prosthesis on elderly patients undergoing hip arthroplasty.Methods From February 1997 to May 1999,96 patients Were treated with hydroxyapatite (HA) coated prosthesis and followed up for their hip arthroplasty.Their results were studied clinically and roentgengraphically to evaluate chiefly their Harris scores,complications and thigh pain.The survival of prosthesis was evaluated according to Kaplan-Meier methods.Results The 60 cases were followed up for eight years on average(range,sevon to nine years).Their mean Harris scores were improved from 42 preoperatively to 90 postoperatively.Fifty-eihgt cases felt no pain at their hip,but two did at their thigh.No radiolucent lines were observed.All the prostheses achieved bony stabilization and remolding.Conclusions HA coated prosthesis can achieve fine fixation,because it helps bone conduction,resists axial force and torsion,and reduces operative risks.

Total Hip Arthroplasty with Hydroxyapatite-Coated Anatomic Femoral Stem / 대한정형외과학회잡지

PURPOSE: To evaluate minimum 5-year results of total hip arthroplasty using a hydroxyapatite (HA)-coated anatomic femoral stem. MATERIALS AND METHODS: Fifty hips in 46 patients, received total hip arthroplasty using a HA-coated anatomic femoral component, between March 1992 and April 1995, 39 hips (36 patients) were available for this study. RESULTS: The mean preoperative Harris hip score of 55.2 points increased to 91.5 points at one year, but reduced to 81.9 points at the last follow-up. Radiolucency was seen in 5 hips (12.8%) on the last follow-up radiograms. Femoral osteolysis occurred in 7 hips (17.9%) on the last follow-up radiograms. Four femoralstems (10.3%) were revised due to femoral osteolysis and loosening. The average duration between index operation and revision was 123 months. CONCLUSIONS: The HA-coated anatomical femoral stem gave an increased Harris hip score and lowered the incidence of thigh pain, however it did not prevent osteolysis due to polyethylene wear.

The early results of total hip replacement with a proximally hydroxyapatite-coated femoral component / 中华创伤骨科杂志

Objective To summarize the early results of total hip replacement with a proximally hydroxyapatite-coated femoral component. Methods From February 2000 to October 2003, 65 cases (70 hips) underwent uncemented total hip replacement with a proximally hydroxyapatite-coated femoral component (U2, United Orthopedic Corporation, Taiwan, China). The diagnosis included femoral neck fractures in 30 cases, osteoarthritis in 15 cases, avascular necrosis of the femoral head in 9 cases, loosening of artificial femoral head in 8 cases, rheumatoid arthritis in 2 cases, and arthrodesis in 1 case. Clinical and radiographic evaluations were performed at 1 week, 3 and 6 months postoperatively, and yearly afterwards. Bone mineral density (BMD) of the proximal femur was measured with dual-energy X-ray Absorptiometry (DEXA) for 44 cases. Results Postoperative X-ray films showed that the initial fixation was excellent or good in all the stems. The follow-ups averaged 3 years (2 to 5.5 years). The mean preoperative Harris hip score was 32 (25 to 52) points, which were improved to 96 points at the latest follow-ups. There was no reported incidence of thigh pain at any time throughout our study. And no case needed revision. By the measurements on the X-ray films taken within 1 year postoperatively, 7 of the 70 stems had subsidence of less than 1.5 mm. No hip experienced extensive proximal end osteolysis, intramedullary osteolysis, or loosening. DEXA showed that the BMD values decreased after operation, and then returned rapidly to the normal or near normal ones 3 to 6 months after operation, especially in zones Ⅱand Ⅵwhere the increase was even more significant than at the control side. All the stems were radiographically stable with evidence of osseous ingrowth typically seen in HA-coated zones, according to the criteria proposed by Engh et al. Conclusions Since HA-coating on femoral implants can enhance the initial fixation of implants, accelerate bone ingrowth and osseous fixation of the femoral component, and seal the interface between the implant and bone to prevent ingress of polyethylene particles, it is helpful in improving clinical results of the cementless total hip replacement.