前腕回内位で起こる尺側手根伸筋腱脱臼・亜脱臼に対する第6区画解離術の1例

Surgical Release for Dislocation of the Extensor Carpi Ulnaris Tendon during Forearm Pronation. Case Report

　前腕回内位で起こる尺側手根伸筋腱(以下，ECU腱)脱臼・亜脱臼に対し，第6区画解離術を施行したので報告する．症例は40歳の男性である．バドミントンのスマッシュ動作により受傷し，受傷後約7カ月時に当科を紹介され受診した．エコー検査上，前腕回内位で手関節を掌・尺屈するとECU腱がulnar grooveより尺側に脱臼する所見が確認された．第6区画解離術を施行し，術後3カ月時，手関節の疼痛は消失しており，術後1年時，手関節の愁訴はなかった．前腕回内位で生じるECU腱脱臼・亜脱臼は典型的な脱臼形態ではないが，第6区画解離術により症状の改善が得られ，本症例のような脱臼形態に対しても本術式は有用であった．

　Traumatic recurrent dislocation of the extensor carpi ulnaris (ECU) tendon is a rare injury and is characterized by painful snapping on the ulnodorsal aspect of the wrist, particularly during forearm supination and wrist flexion.　We encountered a case of ECU tendon dislocation that occurred during forearm pronation.　The patient had sustained a hyperpronation injury during an overhead badminton racket swing 7 months before being seen at our clinic.　Radiograms and CT scans of the patient's wrist showed no abnormal findings.　A dynamic ultrasound examination, on the other hand, revealed ECU tendon subluxation toward the ulnar-volar side upon forearm pronation but not spination.　We surgically released the sixth compartment of the extensor retinaculum, and three months later, the patient had resumed engaging in the same activities at the same level as before injury, and he was asymptomatic.