第2中手骨基部骨折に伴った長母指伸筋腱皮下断裂の1例

Subcutaneous Rupture of the Extensor Pollicis Longus Tendon Following the Second Metacarpal Base Fracture

　第2中手骨骨折を伴った長母指伸筋腱(以下EPL)皮下断裂の1例を経験した．患者はオートバイで転倒し受傷した．X線画像では右第2中手骨基部骨折を認め前腕シーネ固定を4週行った．受傷後4週で右母指IP関節が伸展不能となり，EPLの皮下断裂と診断し，固有示指伸筋腱を用いた腱移行術を行った．受傷機転として手関節の橈背屈強制により第2中手骨基部と橈骨にEPLがインピンジされたために不全断裂をし，さらに母指の運動により完全断裂に至ったと推察された．

　A case of subcutaneous rupture of extensor policis longus (EPL) tendon is due to the second metacarpus bone fracture.　At first the second metacarpus bone fracture was injured by motorcycle accident.　Immediately this fracture was treated by plaster cast from forearm to finger for 3 weeks.　Five weeks after injury, the right thumb showed that it was impossible to completely extension.　The surgical treatment was done with tendon transfer using extensor indicis proprius tendon.　The cause of subcutaneous rupture of EPL tendon is due to impingement between radius and base of second metacarpus.　The mechanism of delayed tendon rupture was suggested that while grasping the steering wheel of motorcycle, wrist joint was deviated to radio-dorsal and then EPL tendon was located between the second metacarpal base and radius, and incompletely ruptured occurred.　However, the thumb was possible to use ordinary, and then EPL tendon showed ruptured completely.