患者，女，６０岁，教师。２０年前无明显诱因始感左腰骶部、左臀部及左下肢疼痛，症状时轻时重，能忍受。坐位左髋、膝关节略屈曲稍抬高左下肢症状可明显减轻。站立弯腰时症状加重。平卧和右侧卧位自觉较舒适，不能下蹲。有时感左小腿外侧麻木。１月前因勉强下蹲后不能自行站 Patient, female, 60 years old, teacher. 20 years ago, there was no obvious incentive for the beginning of the left lumbosacral, left hip and left lower extremity pain, light weight when the symptoms can tolerate. Sitting left hip, knee slightly bent slightly elevated left lower extremity symptoms can be significantly reduced. When standing bent over symptoms. Supine and right lateral position consciously more comfortable, can not squat. Sometimes left lateral calf numbness. 1 month ago due to barely squat can not stand on their own