剣道選手に発生した左小指中手指節（MP）関節の離断性骨軟骨炎の1例

Osteochondritis Dissecans in the Metacarpophalangeal Joint of a Japanese Kendo Player : Case Report

　抄録：症例は14歳，男性，2年間剣道のスポーツ活動を行っていた．主訴は左小指の疼痛と屈曲制限であった．2002年6月，外傷なく，左小指中手指節（MP）関節の疼痛と屈曲制限が出現し，2002年12月3日，症状の改善がないため，当科を受診した．左小指MP関節には軽度の腫脹，圧痛があり，関節可動域は伸展0°，屈曲30°で，運動時痛が認められた．単純X線像は，基節骨基部に軟骨下骨の硬化像と陥凹を示し，断層写真では遊離した軟骨下骨が関節内にみられた．離断性骨軟骨炎と診断し，2002年12月19日に遊離体摘出術を行った．術後5カ月の関節可動域は自動で伸展0°，屈曲50°，他動で伸展60°，屈曲85°で，疼痛は認めなかった．手指における離断性骨軟骨炎は稀で，われわれの渉猟し得た範囲では，手指MP関節の基節骨側に発生した報告はなかった．本症の発生機序は，竹刀を振るという動作により，外力が左小指MP関節に反復性に働いたためと考えられた．

　We treated a case of osteochondritis dissecans in the metacarpophalangeal (MP) joint of a Japanese Kendo player. A 14-year old man complained of pain in his left little MP joint. The pain had started 6 months previously. Physical examination revealed swelling and tenderness on the MP joint. The MP joint had no instability and the range of motion was limited to 0°of extension and 30°of flextion. The x-ray examination showed a consolidation and recess at the base of the proximal phalanx. The tomography showed the subchondral bone was separated from underlying bone in the ulnar side of the base of the proximal phalanx. At surgery it was noted that the articular cartilage of the base of the proximal phalanx was preserved, and the loose body was removed. Five months later after surgery, he had no pain and the range of motion improved. To our knowledge, osteochondritis dissecans at the base of the proximal phalanx has not been reported. We believe the etiology is repeated microtraumas to the MP joint because of swinging a bamboo sword.