患儿:男,13岁。因双膝肿胀半年,于1995年3月2日入院。双膝无疼痛,无外伤史。既往患脊膜膨出致双膝屈曲畸形,近一年加重。体检:双侧腘绳肌挛缩,膝关节肿胀,皮温不高,关节腔积液,髌骨位置正常,浮髌试验阳性,于两侧髌骨上方股四头肌深处各触及半月形孤立的硬性肿物与股四头肌相连,可移动,无压痛,按压肿物时与股骨有撞击感。X 线片见左侧髌骨上10 cm 及右侧髌骨上6 cm处各有一半月形游离骨块,其软骨面光滑,边缘整齐,有正常的松质骨结构,与股骨有一定间隔,双侧髌骨发育、位置、大小基本正常。诊断:双膝副髌骨畸形。行手术治疗,在松解腘绳肌的同时切除副髌骨。术中见股直肌肌腹缩短,而腱性部分明显变长 Children: male, 13 years old. Due to swelling of his knees for six months, on March 2, 1995 admission. No knee pain, no history of trauma. Past suffering from meningocele caused by knee flexion deformity, increased in recent years. Physical examination: bilateral hamstring contracture, knee swelling, skin temperature is not high, joint effusion, patella position normal, floating patella test was positive on both sides of the patella above the quadriceps, each touching the semilunar-shaped isolated hard Mass and quadriceps femoris connected, removable, no tenderness, with a sense of impact on the femur. X-ray film to see the left patella 10 cm and the right patella 6 cm at each half of the free-shaped lunar bone, the cartilage smooth, tidy edges, with normal cancellous bone structure, with the femur with a certain interval, bilateral Patella development, location, size, normal. Diagnosis: Duplex patellar deformity. Surgical treatment, in the release of hamstring resection of the para-patella. Intraoperative see rectus abdominis shortened, while the tendon part of the obvious longer