Abstract: Objective: To determine the relationship between cartilage injury, bone marrow edema, and total bone mineral density in patients with knee osteoarthritis (KOA). Methods: Ninety patients with KOA admitted to the Sichuan Province Orthopedic Hospital between March 2023 and October 2023 were selected, all of whom underwent knee joint MRI and chest QCT examinations. The patients were divided into three groups according to the QTC results: normal bone density, reduced bone mass, and osteoporosis. Patient information, such as sex, age, body mass index (BMI), and course of illness, was also obtained. MRIs of the knee joints were scored separately according to the Recht grading and Whole-organ Magnetic Resonance Imaging Score (WORMS). The bone mineral density (BMD) of the patients was calculated and the BMD values were statistically analyzed using the MR score. Results: No statistically significant differences were observed in sex, BMI, or disease duration among the three groups; however, a statistically significant difference was observed in age. The Recht and WORMS scores among the three groups showed statistical significance between the normal bone density group and the reduced bone mass and osteoporosis groups; however, no statistical significance was observed between the reduced bone mass and osteoporosis groups. KOA cartilage injury was negatively correlated with bone density with a correlation coefficient of r=−0.412, while KOA bone marrow edema was negatively correlated with bone density with a correlation coefficient of r=−0.254. Conclusion: The total bone density in patients with KOA is related to knee joint cartilage injury and bone marrow edema. A decrease in total bone density may indicate the severity of knee cartilage injury or bone marrow edema.