Abstract: BACKGROUND: Warm-needling moxibustion can effectively treat knee osteoarthritis. Degeneration, injury and fracture of the anterior cruciate ligament can affect the local stability of the knee joint, and then induce the formation of knee osteoarthritis. Whether warm-needling moxibustion can repair the injured cruciate ligament and the mechanism of action are still unclear.
OBJECTIVE: To observe the effects of warm-needling moxibustion on the morphology of the anterior cruciate ligament and the expression of insulin growth factor-1 and transforming growth factor-β in rabbits with knee osteoarthritis and to clarify the mechanism of anterior cruciate ligament repair by warm-needling moxibustion.
METHODS: Thirty New Zealand rabbits were randomly divided into blank group, model group and warm-needling moxibustion group, with 10 rabbits in each group. Knee osteoarthritis model was established by plaster cast immobilization. The blank group was not intervened. Rabbits in the model group rabbits were fixed in a rabbit holder for 15 minutes every day. The warm-needling moxibustion group was treated with warm acupuncture, once a day, 7 days as a course of treatment, a total of two courses. After treatment, the imaging changes of the anterior cruciate ligament were observed by MRI and MRI grading statistics were performed. Morphological changes of the anterior cruciate ligament were observed by transmission electron microscope and hematoxylin-eosin staining. mRNA and protein expressions of insulin growth factor-1 and transforming growth factor-β were detected by RT-PCR and western blot, respectively. 
RESULTS AND CONCLUSION: MRI examination: Compared with the blank control group, the anterior cruciate ligament in the model group was thickened, edematous, and partially torn, and the difference in grading statistics was statistically significant (P < 0.05). Compared with the model group, the anterior cruciate ligament in the warm-needling moxibustion group was slightly thickened, with mild edema and no tearing, and the difference in grading statistics was statistically significant (P < 0.05). General observation: In the model group, the surface of the anterior cruciate ligament was glossy and faded, with the edge being covered with flocculent periosteum and obvious tissue necrosis; in the warm-needling moxibustion group, the surface of the ligament was glossy, and the ligament was in a normal helical shape. Hematoxylin-eosin staining: In the model group, there was obvious tissue necrosis in the anterior cruciate ligament, a large number of new capillaries, loosely arranged fibroblasts and collagen fibers. In the warm-needling moxibustion group, there was a small amount of tissue necrosis and few new vessels in the anterior cruciate ligament, and the cells and collagen fibers were loosely and irregularly arranged. Transmission electron microscopy: In the model group, the fibers in the anterior cruciate ligament were arranged in a disordered way with uneven thickness and distribution, and there are more fibroblasts that were irregular in morphology; in the warm acupuncture group, the fibers were basically arranged longitudinally, with uneven thickness and distribution, and a small number of oval-shaped fibroblasts were observed. RT-PCR and western blot assay: mRNA and protein expressions of insulin growth factor-1 and transforming growth factor-β were significantly decreased in the model group compared with the blank control group (P < 0.05), but significant increased after treatment with warm-needling moxibustion (P < 0.05). To conclude, warm-needling moxibustion can alleviate anterior cruciate ligament injury and regulate the expression of insulin growth factor-1 and transforming growth factor-β to treat knee osteoarthritis.

Key words: knee osteoarthritis, warm-needling moxibustion, anterior cruciate ligament, ultrastructure, growth factor