Biocompatibility Evaluation of Heat-treated Mineralized Porcine Cancellous Bone : Using Animal & Clinical Study / 대한정형외과연구학회지

PURPOSE: In our previous study, the authors developed high heat-treated mineralized porcine cancellous bone(TS-GBB, TaeSan Green Bone Block) as bone-substitute. So we projected that this experiments about TSGBB would prove its safety about problems after transplants, and its stability in mechanical strength as the human bone-substitute. MATERIALS AND METHODS: Highly heat-treated mineralized porcine cancellous bone was made. The chemical, mechanical, and morphological properties were evaluated through various tests. Animal study Total 31 New Zealand White rabbits were randomly selected. Bony defect on medial side of the proximal tibia was made. TS-GBB was implanted into the defect area in experimental group, while it was not inserted in control group. For stable fixation self-designed plate of stainless steel was used in both groups. At 2, 8, and 24 weeks, radiological evaluation was performed to measure new bone formation. At 4 and 16 weeks, clinical laboratory tests were performed. Mechanical shear tests were performed for control and experimental groups at 2, 8, and 16 weeks after operation. Also, histological observations were performed by H & E staining at 2 and 16 weeks after operation. Clinical experiments With the approval of IRB in Pusan Paik Hospital of Inje University and Hwasoon Hospital of Chunnam National University, the clinical trials were processed. After harvesting iliac bone for auto grafts from the 40 patients, 20 for each hospital, the TS-GBB were inserted to the donor site. ESR, CRP, WBC count were performed at postoperative time immediately, 1 week, 4 weeks, and 12 weeks to examine possible infection. At 12 weeks after operation, additional X-ray and CT observation were performed. RESULTS: Animal study At all laboratory finding, two group did not indicate a significant difference. At radiologic evaluation, we could comfirm that bone defect size was small gradually by new bone formation in the control group but new bone formation degree was more smaller and slower compared to the TS-GBB group. And at result of biological dynamic stiffness experiments, at postoperative 16 weeks, maximum load at breakage of control group showed to approximately 70% in normal tibia's that. But, maximum load at breakage or yield of TS-GBB group showed to more than 95% in normal tibia's that. In histologic examination, at postoperative 16 weeks, we comfirmed that in control group atypical bony tissue existed in defect site. On the other side, in TS-GBB group new bone formation formed in uniform. Clinical experiments In 20 cases of Inje University, absorption rate was slow a little at 1 case, but the others absorbed normally. In 17 cases of Hwasun Hospital of Chunnam National University, we comfirmed in grade 3 about TS-GBB's absorption and new bone formation at 16 case. At only 1 case, degree of TS-GBB's absorption and new bone formation was poor. In clinical chemistry tests to evaluate the safety, 19 of 20 patients who participated in the experiment in Pusan Paik hospital showed no specific abnormality and showed similar result to preoperative laboratory. In 1 case at postoperative 12 weeks, CRP was elevated, at 16 weeks this patient showed in normal value in ESR, CRP, and WBC count. In 20 patients of Hwasun Hospital all showed similar results to preoperative laboratory in clinical chemistry tests. CONCLUSION: We think that TS-GBB is the suitable material for regeneration of bone defect site as xenograft of clinical bone substitute.

A Study on the Potential of Hydroxyapatite Based Bioactive Bone Cement / 대한정형외과연구학회지

Study on the Potential of Hydroxapatite Based Bioactive Bone Cement PURPOSE: The purpose of this study is to propose a new bioactive bone cement (BBC) composed of bone powder (hydroxyapatite; HA), chitosan powder, and currently available polymethylmethacrylate (PMMA) bone cement for use in orthopaedic surgeries such as vertebroplasty or bone filler. MATERIALS AND METHODS: Three types of proposed BBCs and a currently available commercial PMMA were tested. In vitro studies the surface morphology, chemical composition, changes in pH value along the time, exothermic temperatures, intrusion and cellular responses were investigated. SEM, radiological and histological examinations were performed in animal studies. RESULTS: The major components of BBCs were C, O, Ca, P, Cl, Si, S, Ba and Mg. The pH values in BBCs decreased after 1 day, however they eventually reached 7.2-7.4. The water absorbency, weight loss, and porosity in BBCs increased more than PMMA more than during degradation (p<0.05). However, the compressive Young's moduli and ultimate compressive strength (UCS) of BBCs were lower than those of PMMA (<0.05). The exothermic temperatures of the BBCs were considerably lower than that of PMMA (p<0.05). In view of setting time, it takes relatively longer for BBCII and III to be solidified than PMMA (p<0.05). The intrusion tests showed that the BBCs were more intrusive than PMMA (p<0.05). The cell proliferation test on BBCII showed that the BBCII was more preferable than the PMMA. No cytotoxic characteristics were found in all BBCs. In the animal test, BBC II was more biocompatible as well as osteoconductible than the PMMA. CONCLUSION: The results of in vitro and animal studies indicated that the proposed BBCs have a potential of clinical application as replacement of the current PMMA bone cements.