Influence Of Subchondral Osteoporosis To Progress Of Osteoarthritis

Objective: To research on how sub-articular cartilage osteoporosis impacts on the cataplasis of articular cartilage by means of establish bone rarefaction model and to observe the change of articular cartilage.Methods: One hundred and twenty 3-month-old female Wistar rats was divided into control group 1 (castration control group), castration group, control group 2(retinoic acid control group) and retinoic group at random according to weight, 30 rats in each group. The castration animal model was established by means of cutting both of the ovaries of rats. The incisions were sewed up without ovaries being cut after the operation in control group 1. Rats in retinoic group were intragastric administrated with retinoic acid with the dose of 75mg/(kg·d) retinoic acid every day for 15 days and the same amount of distilled water in control group 2. Execution time, sample acquirement and measurement index: 10 rats out of each group was respectively executed by exsanguination from arteria cruralis on the 4th week, 8th week and 12th week, weight measured before execution. All the articular genu was cut and bone density was measured, including femoral bone and tibia, 3 cm each. Decalcification by 10% EDTA, paraffin imbedding, slice made, staining was done respectively by HE, toluidine blue and safranine, 0.8cm.Sub-cartilage alteration of sclerotin and morphological change of articular cartilage was observed by microscope and assessment to articular cartilage. The thickness of articular cartilage was measured by patho-image analysis system. Creating linear correlation to sub-cartilage BMD and articular cartilage thickness of castration group and retinoic acid group. All the measurable data were done statistically with statistical package.Results: All the rats survived through the experiment except one died in 8th week and the other died in 12th week, both in retinoic acid group. The difference in both sub-cartilage sclerotin and arti cular cartilage is not significant among all the groups. Till the 8th week, the sub-tibia cartilage BMD is significantly higher than control group in both castration group and retinoic acid group (p<0.01). The differences between retinoic acid group and castration group also have statistical significance. Sub-cartilage bone trabecula became thinning, number decreased, succession degraded, discus of bone trabecula stragglingly distributed. On the 12th week, sub-cartilage BMD decrease more in castration group and retinoic acid group(p<0.05), compared to control group. Sub-cartilage bone trabecula became more rarefacted, number decreased more and lost succession. Sub-cartilage bone trabecula in retinoic acid group even disposed in rod-shape or punctiform. All the groups did not differ very much in the thickness of articular cartilage and morphological changes on the 4th week. On the 8th week, compared to control group, cartilage became thinner (p<0.01), cells chaotically diffused, level not clear, cells aggregated in conglobation-shape or nest-shape in castration group and retinoic acid group. The alteration of articular cartilage in retinoic group is more significant compared to castration group. On the 12th week, articular cartilage became progressingly thinner, cells diffused more chaotically, the surface of articular cartilage became rugosited, small fissuration formed on the surface of articular cartilage. Cystogenia group even formed in the cartilage level in retinoic acid group. On the 8th and 12th the differentence between castration group and retinoic acid group on assessment of pathematology is significant (p<0.01). sub-cartilage BMD and articular cartilage thickness of castration group and retinoic acid group is positive correlation.Conclusion: Compare castration group and retinoic acid group with control group, sub-cartilage osteoporosis and corresponding cartilage degeneration can be observed along with time-lapse. The osteoporosis and corresponding cartilage degeneration in retinoic acid group is more severe than castration group in the same period. The aggravation of osteoarthritis aggravate go along with the aggravation of sub-cartilage osteoporosis. Clinically, the effect of treatment on osteoporosis done together with treatment of osteoarthritis is much better than treatment on osteoarthritis alone, for osteoarthritis patients accompanied with osteoporosis.