Walking with a bent knee is mainly considered to be related to inflammation of the knee joint, internal structural damage or calcium deficiency. 1. Inflammation of the knee joint: If inflammation occurs inside the knee joint, such as osteoarthritis, the stimulation of inflammation will easily affect the structure of the knee joint, thus producing the symptom of bending the knee when walking with the leg not straight. 2. Damage to internal structure: If there is damage to the structure of the knee joint such as meniscus or cruciate ligament, it can affect the function of the knee joint, resulting in symptoms of walking with a bent leg, usually accompanied by pain and swelling. 3. Calcium deficiency: If there is a significant lack of calcium in the body, it is easy to cause osteoporosis, which affects the function of the bone and joints, resulting in the phenomenon of bending the knee when walking. If the symptom of walking with legs not straight and knees bent lasts for a long time, you need to go to the orthopedic department as soon as possible to have a medical checkup, to clarify the cause of the disease and then carry out the treatment to restore the function of the knee joints, to prevent the sequelae of motor dysfunction in the later stage, which will affect the posture of the walker otherwise.