The knee osteoarthritis is a common joint disease that causes pain and inconvenience. Clinically, patients with knee osteoarthritis often have response points on the gastrocnemius. Gastrocnemius plays an essential role in stabilizing joints and changing gait and pace, which also has a close relationship with the knee joint. The objective of this study is to determine changes in the tibiofemoral joint after medial and lateral gastrocnemius injury. Rabbits were divided into a medial gastrocnemius injury group, a lateral gastrocnemius injury group, and a control group with two intervals: 6 and 8 weeks after modeling of the semisevered gastrocnemius. The gastrocnemius was weighed and sectioned for histology. The joint space and subchondral bone were observed using X-ray and microcomputed tomography. The cartilage was observed histologically using Safranin O fast green and Masson and immunohistochemically using antibodies to collagen type II, matrix metalloproteinase 13, and integrin beta1. Results showed muscle fiber atrophy, and fibrotic changes occurred after gastrocnemius semidissociation. After gastrocnemius injury, the femoral condyle of the tibiofemoral joint produced abnormal sclerosis and bone degeneration. The pathological changes of cartilage included disordered or reduced cell alignment, cartilage matrix loss, and collagen loss due to decreased collagen type II and increased matrix metalloproteinase 13 activity. The increase of integrin beta1 in the injured group may be related to mechanical conduction process. The results suggest that gastrocnemius injury is an essential factor in tibiofemoral arthritis.

Objective Acupotomy based on the meridian-sinew theory of traditional Chinese medicine has benefits in treating knee osteoarthritis (KOA). The current study aims to prove that acupotomy at the sinew points of Sanheyang protect the knee joint and alleviate the progression of moderate KOA by evaluating KOA symptoms, cartilage structure, and analyzing the changes of cytokines in rabbit cartilage. Methods The model used was mono-iodoacetate-induced moderate KOA in the rabbit’s right leg. Rabbits were divided into the model group, the acupotomy group, and the control group, with each group receiving two parts of treatment for 2 weeks and 4 weeks. We evaluated pain in the knee joint and range of motion. The articular cartilage sections were stained with Safranin O/Fast Green and Masson. We used immunohistochemistry and real-time PCR to detect the protein and mRNA expressions of collagen prototype II (COL-II), matrix metalloproteinase 13 (MMP13), and integrin-β1 (ITG-β1). Results Compared with the model group, the acupotomy group had higher body weight, lower pain score, higher range of motion, lower Mankin score, and significantly lower protein and mRNA expression of MMP13. After 4 weeks of treatment, Col-II expression in the acupotomy group was significantly higher than that in the model group and the expression of ITG-β1 in the model group was abnormally increased. Conclusion Acupotomy at Sanheyang improved the pain symptoms and range of joint motion in rabbits with moderate KOA, and could protect Col-II by regulating MMP13, which may be related to ITG-β1-mediated mechanical force transmission, thus reducing the damage to cartilage structure and delaying the progression of moderate KOA.