Differential diagnosis of muscle paralysis below the thigh or knee: 1. Lower limb muscle paralysis: lower limb muscle paralysis is a symptom of crural myelopathy. Weakness of the lower limbs: weakness of the lower limbs is mostly caused by crural cervical spondylosis, which is manifested as weakness of the lower limbs, numbness, tightness, and heaviness of lifting steps, and gradually there will be limping, trembling, shaky gait, and easy to fall. 3.Central paralysis of lower limbs: central paralysis of lower limbs is the clinical manifestation of congenital hydrocephalus. When hydrocephalus is severe and progresses rapidly, it may also appear, and its symptom is repeated vomiting. Cerebral degenerative changes, brain development disorders, central paralysis of the limbs, especially the lower limbs.