The Effect Of L3-L4Dorsal Rhizotomy On Cartilage And Subchondral Bone Of The Proximal Tibia In Rats

Objective To evaluate the effect of L3-L4posterior rhizotomy on cartilage and subchondral bone of the proximal tibia in rats.Methods27Wistar rats were randomly divided into two groups, the normal control group (9) and experimental group (18).The skin and the subcutaneous tissue was cut open, the right dorsal roots of the third and fourth lumbar (L3and L4) nerve was cut off carefully in the experimental group rats. No surgery in the normal control group rats. All the rats were trained by walking30minutes everyday compulsively one week after operation. The specimens of the proximal tibia were harvested at2,6and10weeks after operation. The morphological feature of the cartilage and subchondral bone of the proximal tibia by hematoxylin-eosinstaining (HE) was observed. The protein expressions of AQP1and MMP1in osseous tissue were investigated by immunohistochemical staining and Sample PCI image analysis system. ANOVA (analysis of variance) and LSD (Least-significant difference) were used for analyzing means of the datum.Results The right knee joint function recovered nearly normal in two weeks after the operation. HE showed that the surface of the articular cartilage of the proximal tibia was smooth, cartilage cells arranged regularly, cartilage structure was clear, the thickness of subchondral bone plate (SCP) and trabecular structure was uniform in the normal control group rats. However, in the experimental group, the surface of the articular cartilage was rugged, cartilage cells proliferated and clustered together, arranged irregularly. Cartilage matrix staining was shallow. The tidemark was copied, drifted and interrupted. Calcified cartilage zone remodeled and incrassated. ACC/TAC increased (articular calcified cartilage, total articular cartilage), BVF (bone volume fraction, BV/TV, bone volume/total Volume) and the thickness of SCP increased, following time and course progressing (t=2.53-12.617, P<0.05). AQP1and MMP1was expressed in non calcified cartilage layer.The pathological changes was becoming more evident with the disease progression. There were significant differences in the pathological changes of cartilage and subchondral bone, and in the protein expressions of AQP1and MMP1of cartilage, between the experimental group and normal control group. There was no positive staining of MMP1of subchondral bone and weak positive staining AQP1(t=2.877-20.414, P<0.01).Conclusion The pathological changes of cartilage and subchondral bone can be caused by the sensory deficit in different ways.