Effect of warm needle moxibustion on morphological changes of cartilage and subchondral bone in knee osteoarthritis rabbits

OBJECTIVE To observe the effect of warm needle with moxibustion (WNM) on morphological changes of articular cartilage and subchondral bone tissues in knee osteoarthritis (KOA) rabbits, so as to explore whether WNM intervention can delay the development of KOA. METHODS Forty male New Zealand rabbits were randomly divided into blank control, model, WNM and medication (Alendronate sodium) groups, with 10 rabbits in each group. A KOA model was established by immobilizing the right hind limb of rabbits with orthopedic casting tape for 6 weeks. The rabbits of the WNM group received WNM stimulation at Neixiyan(EX-LE4) Waixiyan(ST35) and Heding(EX-LE2) for 15 min, once a day for 4 weeks and those of the medication group received gavage of Alendronate sodium (150 μg·kg-1·d-1) once a day for 4 weeks. X-ray examination and magnetic resonance imaging (MRI) scanning were performed to observe the structure of the knee joints. Outcomes of X-ray examination were used to assess the degree of bone hyperplasia and joint space stenosis which were scaled according to Kellgren and Lawrence (K-L) standards, and those of MRI used to evaluate the degree of cartilage damage and bone marrow edema degrees which were respectively scored according to Recht scaling standards and semi-quantitative whole-organ MRI score (WORMS). Histopathological changes (degeneration degrees) of the articular cartilage were observed after H.E. staining, and given Mankin score. The ultrastructure of the cartilage surface and chondrocytes was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. RESULTS Compared with the blank control group, the K-L grade, Recht grade, WORMS and Mankin score of the model group were significantly increased (P<0.05,P<0.01). After the intervention and in comparison with the model group, the K-L grade, Recht grade, WORMS and Mankin score of both WNM and medication groups were significantly decreased (P<0.05,P<0.01). Results of SEM showed severe defect, bulge and uneven surface of the cartilage with irregular growth and regeneration, and those of TEM showed degeneration and swelling of chondrocytes, margination of endonuclear chromatin, reduction in the number of organelles with disordered arrangement, extreme expansion of endoplasmic reticulum with detachment of the ribosome, unclear mitochondria, and disordered distribution of collagen fibers in the extracellular matrix in the model group, which was relatively milder in both the WNM and medication groups. Compared with the medication group, the Mankin score in the WNM group was evidently lower (P<0.05). CONCLUSION WNM can effectively slow down the degeneration of cartilage and subchondral bone of KOA rabbits, delay the development of KOA.