脛骨および大腿骨の骨軟骨腫による膝関節ロッキングの2例

Locking Knee due to an Osteochondroma of the Tibia or the Femur. Report of Two Cases

　大腿骨遠位内側と脛骨近位内側の骨軟骨腫各1例による膝関節のロッキングを経験した．いずれも保存的治療で改善せず，ハムストリングが骨軟骨腫に嵌頓していると診断し，手術を施行した．術中，用手的に嵌頓を解除することはできず，さらにハムストリング腱周囲の腱膜損傷を誘発する可能性があったため，腫瘍摘出を行った．術後，ロッキングは消失した．骨軟骨腫による膝関節ロッキングは無理な屈伸により腱の嵌頓や腱膜損傷が悪化する可能性があるため，治療には腫瘍摘出術が必要であると考えた．

　We report two cases of locking knee as a complication of osteochondroma of a long bone of the lower limb.　In one case the site of the osteochondroma was the medial aspect of the distal femur, and in the other case it was the medial aspect of the proximal tibia.　There was no improvement in either case in response to conservative treatment.　In both cases we determined that the hamstring was trapped by the osteochondroma, and surgery was planned.　Intraoperatively, the hamstring was found to have been trapped by the osteochondroma, and it could not be released manually.　Because forcible manipulation might have damaged the aponeurosis of the hamstring, the osteochondroma was resected, and the locking of the knee improved immediately.　When knee locking is caused by an osteochondroma, since forced manipulation may exacerbate trapping of the hamstring by the osteochondroma or damage the aponeurosis of the hamstring, in our opinion resection of the osteochondroma is the optimal approach.