Abstract: BACKGROUND: Knee osteoarthritis is a common chronic and aseptic inflammation of the knee joint. Its pathological changes start from the articular cartilage. The current diagnosis of this disease mainly depends on clinical manifestations and imaging. However, when the cartilage undergoes pathological changes, the clinical manifestations and X-ray films often show negative results, so MRI has become an important non-invasive examination to identify articular cartilage degeneration.  
OBJECTIVE: To explore the application value of MRI Osteoarthritis Knee Score in the early cartilage degeneration knee osteoarthritis.
METHODS:  Seven Wuzhishan miniature pigs were selected to establish knee osteoarthritis models. Every pig was narcotized, and the anterior cruciate ligament was dissected and stripped in experimental knees. Only the joint capsule of knee in control knees was opened. The joint capsule, subcutaneous tissue and skin were sutured in all knees, and anti-infection treatment was given after operation. At 26 weeks, MRI screening and MRI Osteoarthritis Knee Score were performed on the experimental and control knee joints. Total MRI Osteoarthritis Knee Score was equal to any defect score + full-thickness defect score.  
RESULTS AND CONCLUSION: (1) In the comparison of size of any cartilage loss scores, the experimental side and the control side had statistical differences in the scores of the lateral femur, medial tibia, and lateral tibia (P < 0.05). (2) In the comparison of the full-thickness cartilage loss score, the experimental side and the control side had statistical differences in the scores of each region of the knee joint (P < 0.05). (3) In the comparison of the total scores of articular cartilage injury, the scores of the knee joints of the experimental side and the control side were statistically different (P < 0.05). The scores of femoral region and tibial region were statistically different between the experimental side and the control side (P < 0.05). (4) There was a statistically significant difference in the sub-division scores of the medial femoral area on the experimental side of the knee joint (P < 0.05), and there was no statistical difference in the scores of the other sub-divisions of lateral femur, lateral tibia, medial tibia (P > 0.05). (5) It is indicated that the MRI Osteoarthritis Knee Score system can quantify and analyze knee osteoarthritis cartilage degeneration, and refine the ladder treatment of knee osteoarthritis. It is worth promoting and using in clinical work.

Key words: osteoarthritis, magnetic resonance imaging, knee, cartilage, articular cartilage injury, radiography, early diagnosis, meniscus