| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Tominaga Shinshu University, University Hospital, Assistant, 医学部・附属病院, 助手 (40283270)
KOBAYASHI Seneki Shinshu University, Medical School, Associate Professor, 医学部, 助教授 (40205464)
TAKAOKA Kunio Shinshu University, Medical School, Professor, 医学部, 教授 (30112048)
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| Research Abstract |
Total hip arthroplasty is widely accepted for reconstruction of damaged hip joints in spite of potential risk for mechanical loosening and inevitable revision surgery. In such revision surgeries, we often encounter peri-prosthetic bone defects of various grades either in proximal femur or in acetabulum, which often make difficult to obtain stable setting of a new hip prosthesis even if with use of auto- or allogenous bone grafting and various biomaterials. In order to address this problem, we devised new method to repair the bone defect with use of a growth factor bone morphogenetic protein-2 of human type, produced by DNA recombination ( rhBMP-2) in combination with a new synthetic biodegradable Polymer( PLA-DX-PEG ) as a carrier material for the rhBMP-2 delivery. In this report we present the efficacy of the rhBMP-2 retaining prosthesis to reconstruct bone defect in a canine model. In this model, femoral head and medial halfofthe proximal femur was surgically resected to make the bon
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e defect to be repaired. And the prosthesis with partially porous structured Surface which was impregnated with rhBMP-2 ( 100 μ, 500 μ g or 1000 μ g )/PLA-DX-PEG( 100mg ) composite. In control animals, PLA-DX-PEG polymer without rhBMP-2 was packed into the porous surface. New bone formation at the proximal bone defects was examined by routine radiography at 2, 4, 8 and 12 weeks after surgery. In 100, 500μ g and 1,000 μ g rhBMP-2 groups ( n=4 respectively ) definite radiopaque shadows appeared along the bone defects in 4 week and the sizes of the radiopaque area were depended on the rhBMP-2 doses. The radiopaque shadows became more obvious at 8 weeks alter surgery. In control animals, no radiopaque shadow was noted at the bone defect over the experimental period of time. At 12 weeks after surgery, the animals were sacrificed and proximal femurs were harvested. On macroscopic histology and radiology, original bone defects in 500 and 1,000m μ g rhBMP-2 groups were completely repaired and thef prostheses were well fixed within the proximal femurs. In 100 μ g group, the defects were partially repaired with thin new bone. In controls, the defects were left un-repaired and covered by fibrous tissue. On light microscopic examination, the newly formed bone was remodeled to lamellar bone in 12 weeks. In summary, this type of prosthesis combined with rhBMP-2 delivery system might provide us a new modality to restore bone defect or lost bone mass encountered in revision arthroplasty without bone grafting. Less
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