Children with cerebral palsy may experience a variety of disorders and postural abnormalities, and knee extension is one of the common symptoms. Many parents and patients will ask when they see a doctor: Doctor, why does the child have knee reflexion? Can knee reflexion not be treated? Professor Chang Chongwang of Northwest Cerebral Palsy Treatment Center said: “Knee reflexion must be dealt with, if Failure to deal with or even improper handling may lead to aggravation of the child ’s symptoms, or even severe disability in standing and walking. ”So, why do children with cerebral palsy have knee reflexion? Professor Chang Chongwang introduced as follows: 1. When children with cerebral palsy appear shares When the quadriceps is paralyzed or the muscle strength is low, the child’s hamstring muscle strength is weakened, and the knee joint is unstable in the straight position. At this time, if the weight is loaded, there will be forced to walk in the extended position. 2. When a child with cerebral palsy is paralyzed or has weak hamstrings and triceps of the lower legs, the back of the knee, including the joint capsule and ligaments, are relaxed, and the patient will show knee flexion. 3. When children with cerebral palsy have poor muscle movement control ability, the lack of simultaneous contractility can lead to instability of the child’s knee. 4. When a child with cerebral palsy develops excessive tension of the quadriceps muscle, especially the rectus femoris muscle, it causes stiffness in standing or supporting. The trunk flexes forward while advancing, and the gravity line falls in front of the knee joint, prompting the knee joint to extend to maintain balance . 5. When a child with cerebral palsy develops spasm or contracture of the triceps of the calf and the gravity line falls in front of the knee joint, compensatory knee flexion is formed. 6. When a child with cerebral palsy has sensory dysfunction in the knee joint body, the knee joint has poor control ability. At this time, in order to increase joint stability, the knee joint will be forced to lock in the posterior extension position and knee reflexion occurs. Finally, when a child with cerebral palsy has a long-term knee flexion deformity, it will cause patellar ligament relaxation. When the hamstring muscle is loosened, the child will have knee flexion, which is also a common cause of knee flexion in children with cerebral palsy.