Why do some people have O-legs or X-legs?

O-leg is called genu varus in medicine, commonly known as "bow leg", "bow leg" and "basket leg" It means that at the knee joint, the calf and tibia rotate inward at a certain angle, so it is called "genu varus".

Calcium deficiency and heredity are two foundations for the formation of O-legs, but the more direct reasons are walking posture, standing posture, sitting posture and some exercise.

Knee valgus, also known as leg touching, commonly known as "external splayed leg", is a common deformity of lower limbs. Its deformity is the opposite of genu varus. When the lower limbs naturally straighten or stand, when the knees collide, the inner ankles of the feet are separated and cannot be brought together. The genu valgus of both lower limbs is X-shaped, so it is also called X-shaped leg. The genu valgus of a lower limb is in the shape of "K", also called "K" leg.

It is very complicated, mainly due to the following reasons: 1, knee joint deformity caused by rickets or osteomalacia (due to lack of vitamin D); 2. Polio causes abnormal development of femur or tibia; 3. callus injury leads to abnormal development of femur or tibia; 4. Osteomyelitis leads to abnormal development of femur or tibia; 5. Other diseases (such as fracture, trauma, sequelae caused by osteoma) lead to abnormal development of femur or tibia.

Contrary to the O-leg, the X-leg refers to the gait in which the knees touch each other at first, but the feet can't get close to each other, and the knees "fight" and touch each other when walking.