TAKAGI Michiaki Yamagata University School of Medicine, Orthopaedic Surgery, Assistant Professor, 医学部, 助手 (40241707)
OGINO Toshihiko Yamagata University School of Medicine, Orthopaedic Surgery, Professor and Chair, 医学部, 教授 (60109436)
須田 昭男 山形大学, 医学部, 助教授 (80045715)
|Budget Amount *help
¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1996: ¥2,400,000 (Direct Cost: ¥2,400,000)
The study was performed in order to clarify the cascade of biological host response in loose artificial hip joints from 1996 to 1998 academic year. The research consisted of two aspects ; 1) application of experimental animal model to osteolysis phenomena and its morphological and biological analyses, and 2) morphological and biological analyses on the retrieved tissue samples of loose hip joint at revision surgery.
In animal experimental model, mice were not appropriate for the insertion of implant due to the narrow femoral canal. In stead, modified Howie model was applied to examine the local host response in rat knee synovium and pen-implant tissues after insertion of implants, which followed by injection of polyethylene particle (3 micron and 30 micron in diameter) every two weeks at 2, 4, 6, 8 weeks after surgery. The rats were sacrificed, and the synovial tissues and bone-implant interface were analyzed by immunohistochemically and morphologically with bone labeling of tetracyclin
e and confocal laser scanning microscopy system. As well as synovial tissues, monocyte/macrophages and foreign body type-giant cells were found in the granulomatous tissues, which phagocytozed or surrounded the polyethylene particles, In the tissues, monocyte/macrophages, foreign body type-giant cells, activated fibroblasts, and vascular endothelial cells were the main cell types, where expression of MMPs and bone desorbing cytokins were found and the host reaction were marked in 3 micron injection group than 30 micron group. In peri-implant bony tissues, not only osteolytic region but also osteogenetic region was clearly demonstrated by tetracycline labeling and confocal laser scanning microscopy. These findings indicated the presence of high turn-over bone remodeling in loco bone-implant interface as a result of adverse biological host reaction.
In the analyses on the retrieved tissue from the patients with loose artificial hip joints, same types of cells, namely, monocyte/macrophages, foreign body type-gian cells, activated fibroblasts, and vascular endothelial cells, were found as well as polyethylene wear debris. In addition, the presence of MMP type proteinases and bone resorbing cytokines were demonstrated by immunohistochemistry and molecular biological methods.
The evidence obtained from the experimental animal model and the analysis of the retrieved tissues from the patients with loose hip joints suggested that loosening of well-inserted total hip prostheses, which were combined with periprosthetic weakening and osteolysis, was induced as a result of biological host response where prominent high turnover bone remodeling and cellular response played an important role, which associated with mechanical stress to the bone. Less