| [Objective] To establish a newly osteoarthritic model by increasing stiffness of subchondral bone with composite material PMMA/HA to simulate subchondral bone sclerosis, from which assess the histopathologic changes to investigate the mechanism responsible for osteoarthritis.[Methods] To obtaine the composite material PMMA/HA, adjusted the proper proportion among polymethylmethacrylate (PMMA), methylmethacrylate (MMA), hydroxyapatite(HA) and distilled water to decrease the maximum reaction temperature less than 40℃. All composite materials PMMA/HA were compressed on a mechanical material machine to determine their ultimate strength and stiffness, then compared with subchondral bone. Twenty-four 6～8-month-old white rabbits were randomly divided into four groups, 6 in each group, named 3, 6, 9 , 12-week-postsurgery group respectively. Scraped the subchondral bone below the cartilage of medial tibial plateau, where formed an cavity with diameter 5mm and depth 7mm, whereafter, filled the cavity with the composite material PMMA/HA, the opposite knee of 12-week-postsurgery group was looked as control group and selected randomly 6 normal knees as blank control. Rabbits were sacrificed at the 3rd, 6th, 9th and 12th week respectively, the changes of articular cartilage of medial tibial plateau were assessed at gross morphological and histological levels. Transmission electron microscope(TEM) examined the ultramicroscopic changes of chondrocytes in blank control, 6 and 12-week-postsurgery groups. Expression levels of collagen type Ⅱ and MMP-1 were probed by immunohistochemical method respectively.[Results] The mean maximum reaction temperature of the composite material PMMA/HA was 38.17℃, ultimate strength and stiffness were higher than...
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