BACKGROUND:Knee joint is the most complicated structure of human body, and X-ray is often used to reflect the stenosis of knee compartment. However, radiographs are two-dimensional projection of three-dimensional joint structure. Thus, different joint shooting locations can impact the outcomes of measurement, and it is difficult to ensure the accuracy of repeated measurements. OBJECTIVE:To build three-dimensional model of knee compartment, measure the distance and volume, and provide the basis for subsequent models, biomechanics and relevant clinical studies. METHODS:Based on the principle of reverse engineering, using CT images of the knee joint and the software of Mimics, three-dimensional model of medial compartment knee structure was reconstructed. After the model was imported and smoothed, the medial and lateral compartment volumes were finaly calculated by the software of Geomagic Studio. RESULTS AND CONCLUSION: Three-dimensional model of the knee compartment, including femur, tibia and fibula, was successfuly structured by CT images. The models of knee and knee compartment could be observed at any angle or observed individualy, and could be measured. It was discovered that the volume of medial and lateral compartments of knee is close, although the joint space width of them is different, which ilustrates that the procedure can accurately reflect the degree of knee joint space width in the round by calculating the volume of medial and lateral compartments of knee joint through computer.