Objective: To study the etiological factors of knee osteoarthritis and to provide the anatomical basis of corrective therapy for knee joint deformity by comparing the biomechanical differences of the knee joints between the osteoarthritis patients and the normal people.Methods: The sexes, ages, heights, weights, painful characters and accompanied symptoms were recorded, and the femoral angle, tibial angle, femorotibial angle, joint space angle, and the height and width of condylus medialis and lateralis were measured for 29 selected knee osteoarthritis patients. And the biomechanical data of the patients were compared with those of the 19 normal people.Results: The femoral angle of the osteoarthritis patients was smaller and the joint space angle was greater statistically than that of the normal people, and the ratios of height and width of condylus medialis and condylus lateralis of the osteoarthritis patients were greater than those of the normal people.Conclusion: In the patients, the gravity line of the lower limb inclines to the condylus medialis, so the condylus medialis is more vulnerable. And the configuration of the condylus of the patients, which is narrower and longer, is different from that of the normal people. It may be one of the etiological factors of knee osteoarthritis.

Key words: osteoarthritis, knee, X-ray, diagnosis, biomechanics, pathogeny