Long and short legs can actually be divided into two categories: structural (true unequal leg length) and functional. Structural shortness of leg is a shortening of the skeletal structure and is a fixed bone deformity. It is often due to a previous fracture of the lower leg bone or thigh bone, which, after healing, has reduced in length. In some special cases, such as cerebral palsy, asymmetrical growth of the lower extremities during growth is also often seen. Functional asymmetry is caused by incorrect posture of the spine, pelvis, ankle, etc., or by weakness. This includes hip dislocation. On examination, the physician often uses a ruler to measure from one skeletal fixed point to another in order to measure the true leg length. Comparing the distance from the anterior superior iliac spine to the medial ankle of each leg will tell you if there is a true leg length discrepancy. The difference in length comes from the femur and tibia. In some children, the true leg length measurements are equal, even though the appearance of the legs are not equal. This may be a functional short leg due to scoliosis or pelvic tilt, meaning that the legs are “unequal in appearance” rather than “unequal in true leg length”. Why does this happen? 1, the hips, lumbar spine and pelvis around the muscle tension imbalance, so that one side of the pelvis is pulled up or spinal scoliosis, our body’s center of gravity will be out of balance, the left and right sides of the lumbaris major muscle tension imbalance, for example, one side of the lumbaris major muscle tightening, which side of the pelvis will be tilted, and then the spine scoliosis, the pelvis a high and a low, and then the short and long legs appeared. 2, the imbalance of the muscles around the hip makes the neck of the femur tilted excessively forward or backward. Since the rotor of the thigh bone is embedded in the hip joint at an angle of 135 degrees rather than like a stick straight into the joint, abnormal anterior or posterior tilting of the femoral neck will lead to a high or low pelvis. 3, asymmetric foot problems, for example, one foot arch is normal, the other foot is flat foot or high arch foot, which is not the foundation of the situation, easy to lead to long and short legs, the human body itself is a self-balancing whole, the scoliosis of the spine or pelvis is sometimes skewed in order to balance the body part of the obstacle or defect. The foot is an area of concern. The problem of short and long legs, most of them are functional. Although the legs are not really unequal in length, the phenomenon of different leg lengths means that the pelvis is skewed, the spine is scoliosis, and the body is unevenly stressed. Over time, the lower back, hips, and knees will also be seriously affected. Treatment: If it is structural unequal length, then you need to see a doctor earlier to determine how much the difference in length is, and intervene early with rehabilitation works (i.e. orthopedic shoes or orthopedic insoles), and have regular checkups at the hospital to adjust the insole height (especially for developing children). If it is determined that the difference in leg length is not structural but only cosmetic, the cause needs to be addressed and treated symptomatically.