Objective To investigate the effect of extracorporeal shock wave (ESW) on physically or hormonally induced femoral head necrosis of rabbits, and to study the underlying mechanism. Methods Twenty two Japanese rabbits were randomly divided into two groups: group A and group B. Different methods were used for each group to establish the model of bilateral femoral head necrosis: freezing for group A and hormone injection for group B. The right hind limbs of all rabbits were used as the treatment side treated with ESW while the left hind limbs as control without any treatment. The rabbits were sacrificed at 2, 4, 8 weeks, respectively, after the treatment. X ray, pathological and electron microscope examinations were adopted to observe the changes of the femoral head. Results At the 8th week after ESW treatment, X ray imaging showed less severe cave in on the femoral head of the control side than that of the treatment side in both groups. The empty lacunae ratio, the number of the osteoblast and the blood vessels were significantly different between the treatment and the control sides, but not between the two groups. Conclusion ESW is an effective treatment for the physically and the hormonally induced femoral head necrosis. The mechanism may include recanalization of the blocked vessel and promotion of the osteoblast growth.

A type of water-soluble carboxymethyl chitosan (O--CMC), with 76% degree of substitution determined by conductivity method, was prepared by using chloroacetic acid to react with C6-OH of chitosan. The solubility of O--CMC was characterized also. Animal experiment in rabbits showed that O--CMC could lubricate arthron, inhibit proliferation of fibroblast cells on rabbits' knee joints, benefit the process of repairing pathologic articular cartilage, and produce good therapeutic effect on rheumatoid arthritis.
Animals ; Arthritis, Experimental ; drug therapy ; pathology ; Cartilage, Articular ; drug effects ; Cell Proliferation ; drug effects ; Chitosan ; administration & dosage ; analogs & derivatives ; therapeutic use ; Female ; Fibroblasts ; drug effects ; Injections, Intra-Articular ; Knee Joint ; drug effects ; Male ; Rabbits