1998 Fiscal Year Final Research Report Summary
Cellular Mechanism of Pathological Bone Resorption in Orthopaedic Disorders
| Project/Area Number |
08671680
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthopaedic surgery
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| Research Institution | Osaka City University Medical School |
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Principal Investigator |
KADOYA Yoshinori Osaka City University Medical School, Dept.orthopaedic Surg., Lecturer, 医学部, 講師 (20204521)
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| Co-Investigator(Kenkyū-buntansha) |
YUTANI Yasutaka Osaka City University Medical School, Dept.Orthopaedic Surg., Associate Prof., 医学部, 助教授 (90200873)
OHASI Hirotsugu Osaka City University Medical School, Dept.Orthopaedic Surg., Assistant Prof., 医学部, 助手 (70254406)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Bone resorption / Osteoclasts / Macrophages / Total Joint Replacements / Histomorphometry / Osteolysis / Wear / Wear particles |
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| Research Abstract |
This summarizes the results of our recent studies on the pathogenesis of osteolysis around total joint arthroplasties. First, interface tissues with adjacent bone were retrieved and histopathologically investigated with reference to the cells on the bone surface. Second, polyethylene particles were extracted with tissue digestion method and characterised using scanning electron microscopy. Finally, an animal model for osteolysis was created and various interface conditions were compared in view of their resistance to particle migration. Histopathological examinations demonstrated that active bone formation, regarded as a repair process, was the most common feature even in revised cases. They also highlighted the role played by macrophages, not as cells producing inflammatory mediators which could activate osteoclasts, but as cells primarily responsible for the bone loss in osteolytic lesions. Among the particle species present, only polyethylene particles were shown to play a significa
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nt role in macrophage recruitment and subsequent osteolysis. A quantitative extraction of polyethylene particles demonstrated a significant difference in the "number" of particles between osteolysis positive and negative cases whereas the "size" of particles was similar between these two groups. The critical number of particles for osteolysis was around 1x10^<10> particles / g tissue and cellular reaction against phagocytosable particles accumulated over this concentration could be the prerequisite for the progression of osteolysis. The animal model for osteolysis indicated that the progression of osteolysis depended on the integrity of bone-implant interface. We propose that the solid fixation of the prosthesis performed by contemporary techniques (e.g. improved cementing technique, hydroxyapatite coating) is beneficial to prevent particle migration and subsequent osteolysis.
A comprehensive understanding of the bone reactions in osteolysis including the basic mechanisms of bone loss, demonstrated in this study, are critical to the development of preventive measures that may minimise the clinical impact of this phenomenon. Less
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