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

An, Ki Chan; Choi, Jang Seok; Kim, Tae Hyung; Lee, Yong Jae; Yoon, Taek Lim; Shin, Jung Woog; Chung, Hoon Jae; Kim, Sang Woo

Abstract

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.