Diagnostic Value of 3.0T MRI in Cartilage Injury Grading of Knee Osteoarthritis
Authors: Zhang Xiaoming , Tong Haiyang , Zhang Jin , Xu Jinyong , Xia Shiyong 
Published: September 2020

Objective: At present, the grading diagnosis of knee osteoarthritis is mostly subjective evaluation, and lack of quantitative criteria, which brings some difficulty to diagnosis. To solve this problem, this study selected easily quantifiable indicators, such as cartilage thickness,
cartilage volume and signal value, and analyzes their application value in grading diagnosis of cartilage injury by observing their change characteristics under MRI. Methods: Clinical data were collected from 54 patients with osteoarthritis of the knee (KOA) and 12 healthy volunteers,
including 27 males and 39 females; age 38–63 years, with an average age of 47 ± 6.9 years. A total of 110 knee joints were tested, including 86 affected and 24 healthy joints. MRI data were collected, including patella, medial and lateral femoral condyle, medial and lateral tibial
condyle, and for grading. The results were compared with those of arthroscopy to analyze the consistency of the two diagnostic methods. The 110 knee joints were divided into 5 groups according to the arthroscopic grading (0–IV grade), and compare the differences of cartilage thickness,
cartilage volume and signal value under MRI among groups. Result: Among them, in terms of MRI grading, there were 15 cases of I grade, 21 cases of II grade, 26 cases of III grade, and 24 cases of IV grade. In terms of arthroscopy grading, there were 16 cases of I grade, 23 cases of
II grade, 25 cases of III grade, and 22 cases of IV grade. The kappa value of the two diagnostic methods was 0.91, with high consistency (P < 0.01). According to the results of arthroscopic grading diagnosis and analysis of the corresponding MRI data, it was found that the average
thickness of normal articular cartilage in the patella, lateral tibia condyle, medial tibia condyle, lateral femur condyle, medial femur condyle is gradually thinning, and the thickness of articular cartilage in each part gradually thinned with the increase of injury grade. The difference
between I grade and 0 grade was not statistically significant, and except for that, among other groups there were statistically significant (P < 0.01); The volume of normal articular cartilage decreased from medial femoral condyle, lateral femoral condyle, patella, lateral tibial
condyle and medial tibial condyle in turn, and the volume decreased gradually with the increase of injury grade. Except for the difference between I grade and 0 grade, there were statistical significance between other groups (P < 0.01); signal value of normal articular cartilage
decreased from medial tibial condyle, lateral femur condyle, medial femur condyle, lateral tibial condyle and patella in turn. Signal value increased with the increase of injury grade. Except for the difference between III grade and IV grade, there were statistical significance between other
groups (P < 0.01). Conclusion : MRI grading of cartilage injury in knee osteoarthritis is highly consistent with arthroscopy, with high accuracy. In MRI grading, reference to cartilage thickness, cartilage volume and signal value can effectively improve the diagnosis rate.