[Biomechanical effect of acupotomy on cartilage degeneration in rabbits with knee osteoarthritis]

To observe the effects of acupotomy on the biomechanical characteristics and cartilage degeneration of knee joint in rabbits with knee osteoarthritis (KOA) , and to explore the therapeutic mechanism of acupotomy in treatment of KOA.

Twenty-four 6-month-old male New Zealand rabbits were randomly assigned to a normal group, a model group and an acupotomy group, 8 rabbits in each group. Except the normal group, all other groups underwent the modified Videman method to induce KOA by immobilizing the left hind limb in extension for 6 weeks. In the acupotomy group, acupotomy was operated at the left knee on the tendon insertions of the vastus medialis, vastus lateralis, rectus femoris,and biceps femoris, and on the pes anserine bursa, once a week for 3 weeks. Before and after intervention, the score of Lequesne MG and passive range of motion (PROM) were observed in the knee joint of the rabbit's left hind limb. After intervention completion, the root mean square (RMS) of surface electromyographic signals from the flexor and extensor muscle groups of the knee joint of the rabbit's left hind limb was evaluated, the knee joint force exerted by the left hind limb at the moment of takeoff was collected. Immunofluorescence staining was used to detect the fluorescence intensity of type Ⅱcollagen (Col-Ⅱ) in the knee cartilage of rabbit left hind limb, while ELISA was employed to determine the levels of cartilage oligomeric matrix protein (COMP) and type Ⅱ collagen carboxyl-terminal peptide (CTX-Ⅱ) in rabbit serum.

After intervention, compared with the normal group, the model group showed the increase in the Lequesne MG score (P<0.05),and the decrease in PROM, RMS of the flexor and extensor muscle groups, knee joint force of the left hind limb, fluorescence intensity of Col-Ⅱ in the cartilage of the knee joint of the left hind limb (P<0.05), and the elevation in serum COMP and CTX-Ⅱ(P<0.05). When compared with the model group, the acupotomy group exhibited the decrease in the Lequesne MG score (P<0.05), and the increase in PROM, RMS in the flexor and extensor muscle groups, knee joint force of the left hind limb, fluorescence intensity of Col-Ⅱ in cartilage of the knee joint of the left hind limb (P<0.05), and the decline of serum COMP and CTX-Ⅱ(P<0.05).

Acupotomy can retard cartilage degeneration in KOA by modulating the activation of flexor and extensor muscle groups of knee joint, strengthening knee joint force, and suppressing extracellular matrix degradation.