Numbness of the thigh above the knee is considered to be related to nerve injury, lumbar disc herniation, pyriformis syndrome and other causes. 1. Nerve injury: when the leg is injured, if there is nerve damage, such as femoral nerve injury, it will cause numbness in the thigh above the knee. 2. Lumbar disc herniation: it is caused by degenerative disease of lumbar vertebrae, when the herniated disc causes compression to the nerve root, there will be lumbar pain, buttocks, back of the thigh, calf and foot radiating pain, numbness and other symptoms, so it will also cause numbness of the thigh above the knee. 3. Pearly muscle syndrome: the sciatic nerve from the pear-shaped muscle through and through, when the pear-shaped muscle injury and inflammation, will cause compression of the nerve, will also cause numbness in the thigh above the knee. Visible causes of numbness in the thighs above the knee are very many reasons, such as symptoms have not been able to improve, need to go to the hospital in time to identify the cause of the disease, targeted treatment.