患者，女，52岁，农民。因左膝部无痛性肿块增大影响膝关节活动1年余人院。体检：左膝部骸骨下线隆起，触及5cm×5cm×3cm肿块，质地硬，边缘清，活动度大，无压痛，屈滚关节45°，X线报告：滑膜软骨瘤。在硬膜外腔麻醉下于左膝部作纵形切口，常规切开骸下囊，取出有完整包膜、 Patient, female, 52 years old, farmer. Due to the painless mass enlargement of the left knee, the activity of the knee joint was affected for more than one year. Physical examination: The bulging of the lower tibia of the left knee touches a 5cm × 5cm × 3cm mass, the texture is hard, the edge is clear, the activity is large, there is no tenderness, the flexion joint is 45°, X-ray report: synovial chondroma. Longitudinal incision is made in the left knee under epidural anesthesia, the infrapatellar sac is routinely incised, and the complete capsule is removed.