Objective To investigate the antibacterial and osteogenic capabil ities in vivo of hydroxyapatite (HA)/silver (Ag) coating. Methods HA/Ag coating (Ag qual ity percentage was 3%) and HA coating were deposited to external fixator Schanz screws. The tibial fracture model was establ ished in right hindl imb of 18 adult male Beagle dogs (weighing 15-20 kg). Thetibia was stabil ized with an external fixator and 2 Schanz screws of HA coating at proximal tibia (control group, n=18) and HA/Ag coating at distal tibia (experimental group, n=18), and every screw incision was infected with Staphylococcus aureus. Infection in screw holes and the changes of bone-screw interface were observed by wound grading and X-ray films. Results In control group, wounds infection became worse with time (χ2=13.492, P=0.001), while in experimental group, no obvious change was observed (χ2=0.208, P=0.901). The wound grading of experimental group was significantly better than that of the control group at 1, 2, and 3 weeks (P lt; 0.05). Laser scanning confocal microscope showed that there was bacterial adhesion on the surface of screws in 2 groups, viable becteria mainly in control group and non-viable becteria mainly in experimental group. The scanning electron microscope (SEM) observation results of the fractured sclerous tissue section showed that an obvious transparent boundary between screw and bone in control group, but no obvious boundary in experimental group. The osseointegration ratios were 76.23% ± 15.54% in control group and 93.42% ± 5.53% in experimental group, showing significant difference (t=8.843, P=0.000). The SEM observation showed that HA/Ag coating integrated with new bone and the surface of implant was filled with new bone in experimental group; obvious interspace was seen between the HA coating and new bone in control group. Conclusion HA/Ag coating has good antibacterial and osteogenic capabil ities, so it can take effects in preventing infection in screw holes and loosening of implants.
Objective To investigate aesthetic outcomes and postoperative complications of hydroxyapatite particulate artificial bone for repairing sunken deformation of frontal bone following removal of dermoid cyst. Methods From February 2000 to May 2005, hydroxyapatite particulate artificial bone was used to repair the sunken deformation of frontal bone in 13 cases (9 males and 4 females), and the age of the patients was from 17 to 41 years. The dermoid cysts were all found during infant period, and the length and width of the cysts ranged from 6 cm×4 cm to 10 cm×8 cm. Anincision along the hairedge or tumor margin was made to excise the dermoid cyst in the forehead. After complete removal of dermoid cyst, the sunken frontal bone was examined and repaired with hydroxyapatite particulate artificial bone. The clinical checkup and Xray examination were utilized to determine aesthetic outcomes and postoperative complications at 1 week, 1 month and 6 months after operation. Results The primary wound healing was obtained in allpatients postoperatively, and no complications such as hematoma, infection, recurrence of dermoidcysts or displacement of hydroxyapatite particulate artificial bone were observed. With a followup from 1 to 20 months, all sunken deformations were completely repaired with satisfactorily aesthetic outcomes. Through clinical checkup and X-ray examination, the implants were found to integrate with the frontal bones without any gaps and displacement. Conclusion It is a simple and viable method torepair sunken deformation of frontal bone with hydroxyapatite particulate artificial bone.
Objective To study an optimal ratio of small intestinal submucosa (SIS) and (hydroxyapatite-tricalcium phosphate,HA-TCP,SIS/HA-TCP) compositions according to the effect of SIS/HA-TCP compositions with different ratios on repairing rabbit femoral condyle defect. Methods Thirty-six rabbits were made into bone defect models of 6 mm in diameter and 10 mm in depth in both sides of femoral condyles. Three different ratios of SIS/HA-TCP compositions (w/w: 1, 0.5, 0.25) were implanted into rabbit femoral condyle defect. After 2, 4, 8 and 12 weeks of operation, the repair effect wasobserved grossly. The histological evaluations were performed by histological scoring system and computer imaging analysis system. Results The amount of new bone formation in SIS/HA-TCP(0.5) group was more than that in SIS/HA-TCP(1) and SIS/HA-TCP(0.25) groups. Histological observation: In SIS/HA-TCP(1) group, few new bone formation was seen and bone defect was repaired in the 12th week. In SIS/HA-TCP(0.5) group, immature woven bone was found in the defect in the 2nd week; more immature woven bone appeared and formed trabeculae in the 4th week; the regenerated bone was vigorously growing into the interspaces of the implanted materials in the 8th week; the implanted materials was basically replaced by bony structure and the lamellar bone appeared in the 12thweek. The results of SIS/HA-TCP (0.25) group were similar to that of SIS/HA-TCP(0.5) group. The histological scoring was higher in SIS/HA-TCP(0.5) and SIS／HA-TCP(0.25) groups than that in SIS/HA-TCP(1) group (Plt;0.05) in the 2nd, 4th, 8th, and 12th weeks. The scoring was higher in SIS/HA-TCP(0.5) roup than that in SIS/HA-TCP(0.25) group in the 2nd and 12th weeks(P＜0.05). In new bone formation and the degradation of HA-TCP, SIS/HA-TCP(0.5) and SIS／HA-TCPC(0.25) groups were superior to SIS/HA-TCP(1) group(Plt;0.05), SIS/HA-TCP(0.5) group was superior to SIS/HA-TCP(0.25) group (Plt;0.05). Conclusion SIS/HA-TCP(0.5) has better effects of repairing bone defect and it can be used as a reference ratio in constructing bone scaffolds.
Objective To evaluate the feasibility and the value of the layered cylindric collagenhydroxyapatite composite as a scaffold for the cartilage tissue engineering after an observation of how it absorbs the chondrocytes and affe cts the cell behaviors. Methods The chondrocytes were isolated and multiplied in vitro, and then the chondrocytes were seeded onto the porous collagen／h ydro xyapatite composite scaffold and were cultured in a three-dimensional environme n t for 3 weeks. The effects of the composite scaffold on the cell adhesivity, proliferation, morphological changes, and synthesis of the extracellular matrix were observed by the phase-contrast microscopy, histology, scanning electron micros copy, and immunohistochemistry. Results The pore diameter of the upper layer of the collagen-hydroxyapatite composite scaffold was about 147 μm. and the porosity was 89%; the pore diameter of the bottom layer was about 85 μm and the porosity was 85%. The layered cylindric collagenhydroxyapatite composite scaffold had good hydrophilia. The chondrocytes that adhered to the surface of the scaffold, proliferated and migrated into the scaffold after 24 hours. The chondrocytesattached to the wall of the microholes of the scaffold maintained a rounded morphology and could secrete the extracellular matrix on the porous scaffold. Conclusion The layered cylindric collagenhydroxyapatite composite scaffold has a good cellular compatibility, and it is ber in the mechanical property than the pure collagen. It will be an ideal scaffold for the cartilage tissue enginee ring.
Objective To evaluate the biocompatibility and safety of a novel orthopedics materials-graded zirconia(ZrO2)hydroxyapatite(HA) composite biomaterials. Methods First, ultrafine powers of ZrO2 and HA powder were prepared by chemical precipitation method, then graded ZrO2-HA composite was synthesized by dry-laying and sintering method. After the physiological saline and culture medium extracts of the composite were prepared, four experiments were conducted as follows:① The mouse acute toxic test consists of 2 groups(n=10). The extracts were intravenously injected to mice in the first group, and physiological saline to mice in the second group. The dose was 50 g/kg. Their toxicity manifestation, morality and the change of weight were recorded.② The standard curve of proliferation and metabolism of L929 cells was established. ③ The cytotoxinic test consists of 3 groups: materials group (extracts of the materials), positive control group (culture fluid with 0.64% phenol), and negative control group (RPMI-1640 culture fluid). Each of three was cultured with cell suspension, and then the morphology of the cells was observed, the relative proliferation rate (RGR) was calculated, and the toxicity was classified. ④ In vitrohemolytic test was divided into 3 groups: extracts, sterile distilled water (positive control) and 0.9% physiological saline. In each of three, 0.2 ml anticoagulant diluted fresh rabbit blood was added. The percentage of hemolysis was tested. ⑤ The muscle and implantation test were divided into 4 groups(n=3). The composite biomaterials were implanted into pygal muscleson either side and lateral condyles of femurs. After surgery, the rats of four groups were sacrificed at 12 and 24 weeks respectively.Tissue slice and scanning electronic microscopy were performed. Results General acute toxic test: no mouse died within 3 weeks; no toxicity symptom or adverse effects were shown within 3 days. The weight of materials group increased by 3.57±0.49 g, and the control group by 3.62±0.61 g, showing no statistically significant difference（Ρgt;0.05）.The standard curve of L929 cell perliferation and metabolism showed that their existed a positive correlation between the number of L929 cells and the perliferation. ③ Cytotoxinic test: cytosomes in the positive control group diminished and appeared round, there were pyknotic nucleus, the attached cells agglomerated; the toxicity was level Ⅳ. The morphology of cells in materials groupand negative control group was normal, and the number of them increased; the toxicity was level Ⅰand level 0, respectively. The MTT color experiments showed that positive control group was significantly lower than materials group and negative control group, showing statistically significant difference (Plt;0.01); there was no statistically significant difference between materials group and negative group.④ Hemolytic test: in vitrohemolytic rate of negative control group was0, of positive control group was 100%, and of materials group was 1.66%, which accords with the standard that hemolytic rate should be lower than 5% specified in ISO. ⑤ Implant test:No apparent rejection reaction took place after the composite was implanted; the composite bonded with the bones of the receptors firmly, which had good bonedinduced effect. Conclusion Graded ZrO2-HA composite bioceramic has good biocompatibility and is suitable for orthopedic biomaterials.
Objective To investigate and compare the osteogenic potential of three kinds of calcium phosphate ceramic as carriers for recombinant human bone morphogenetic protein-2(rhBMP-2) in vivo.Methods BCPceramics (HA,TCP,HA/TCP) impregnated with rhBMP-2 (experimental groups) and without rhBMP-2(control groups) were implanted into 6 muscles pockets on the dorsum of 3month-old Wistar rabbits. The rabbits were sacrificed 2, 4 and 8 weeks after implantation and bone induction was estimated by alkaline phosphatase(ALP) activity measurement. The implants were also examined histologically and histomorphometrically by HE staining and computerized graphical analysis. Results The ALPactivity of implants withrhBMP-2 was higher than that of control groups(P＜0.05), but there was no difference between 2 and 4 weeks in experimental groups. In all experimental groups,theimplants exhibited that new bone formation increased with the lapse of time. The amount of new bone formation is more in -HA/rhBMP-2 group than in the other two group in the 2nd and 4th weeks, but there was no difference between them (P＞0.05).In the 8th week, the amount of bone formation was most in HA/TCP with -rhBMP-2, and was more than that in the 2nd and 4th weeks. Whereas in control groups, there was only fibrous connective tissue. Conclusion HA/TCP- is a good carriers of rhBMP-2 and can be used as bone substitutes clinically.
Objective To investigate the influence of different dose levels of hydroxyapatite/tricalcium phosphate (HA/TCP) on the proliferation and alkalinephosphatase (ALP) activity of rabbit osteoblasts. Methods Three different doselevels of HA/TCP (10%, 40%, 70%) were co-cultivated with rabbit osteoblasts respectively. The proliferation and ALP expression capacity of osteoblasts were examined with MTT method and enzyme histochemistry once every 24 hours until 5 days. Three control groups of other materials were treated and examined in the sameway: rabbit osteoblasts as normal control; polyvinylchloride as positive control; titanium alloy as negative control. Results There was remarkable timeeffect relationship in the proliferation of osteoblasts. Ten percent HA/TCP did not affect osteoblasts growth while 40% HA/TCP could slow the cell growth rate down though time-effect relationship still existed. The proliferation of osteoblasts stagnated when co-cultivated with 70% HA/TCP. On the other hand, 10% HA/TCP could cause reversible damage on ALP activity of osteoblasts, whereas when the dose was40%, and the cultivation lasted 6 days the damage was irreversible. Three different dose levels of titanium alloy (10%, 40%, 70%) had no effect on the proliferation or ALP activity of osteoblasts. Conclusion Dosage is an important factor affecting the biocompatibility evaluation of biomaterial. It suggests that dose choosing should be more specified upon each individual biomaterial. It also indicates that ALP may be a good supplementary index of the cell compatibility of material.
OBJECTIVE: To evaluate the clinical effect of drilling procedure following the hydroxyapatite orbital implantation. METHODS: From February 1996 to April 2000, 146 consecutive patients who received hydroxyapatite orbital implant were drilled and inserted a motility peg 6 to 16 months after hydroxyapatite implantation. Among them, there were 97 males and 49 females, aged from 18 to 60 years old, of the 146 motility pegs, 36 were sleeved pegs and 110 were nonsleeved. Goldman visual field analyzer was applied to measure the degree of artificial eye’s movement before and after drilling. RESULTS: Followed up for 1 to 40 months, no secondary infection occurred. The mobility of the prosthesis increased from (18.7 +/- 3.8) degrees preoperatively to (42.3 +/- 3.7) degrees postoperatively. CONCLUSION: The delayed drilling procedure and motility peg insertion improve the range of movement and the sensitivity of the artificial eye with a low rate of complications.
OBJECTIVE: To study the effect of collagen/hydroxyapatite(CHA) instead of autogenous bone transplantation on repairing the mandibular defects. METHODS: Ten Chinese experimental minipigs were made 2 cm bone defects in diameter in the mandible. The experimental group was implanted CHA, while the control group was implanted autogenous bone. The basic parameters of bone dynamics were determined by bone metrology. RESULTS: There was remarkable difference between the two groups in the mean distance and mineralization apposition rate of double label bands marked by tetracycline(P lt; 0.05), while the mean osteoid seam width and mineralization lag time had no remarkable difference(P gt; 0.05). It suggested that CHA had good osteogenesis. The collagen in CHA offered the condition of bone mineralization, and the mineralization peak of experimental group was present at 4 weeks earlier than that of control group (8 weeks). CONCLUSION: CHA may be a substitute of autogenous bone transplantation in repairing the mandibular defects, and the second operation for offering the implanting bone is avoidable, therefore, CHA may be an ideal material to repair bone defects.
OBJECTIVE To confirm membrane-guided tissue regeneration in the healing course of segmental bone defects and study the mechanism. METHODS Segmental, 1 cm osteoperiosteal defects were produced in both radii of 12 rabbits. One side was covered with hydroxyapatite/polylactic acid(HA/PLA) membrane encapsulated as a tube. The contralateral side served as an untreated control. Healing courses were detected by radiographic and histologic examinations. RESULTS All control sides showed nonunion, whereas there were consistent healing pattern in test sides. CONCLUSION Membrane technique can promote bone regeneration.