環椎外側塊スクリューを用いた環軸椎後方固定術

Atlantoaxial Fixation with C1 Lateral Mass Screw

　環椎外側塊スクリューと軸椎椎弓根スクリューを用いた環軸椎後方固定術（C1LM-C2PS）の報告は，近年散見されるようになってきたが本邦での報告は少数である．今回，本法を施行した5例を報告し，若干の考察を加えた．症例は環軸椎不安定性を認めた5例（男性4例，女性1例）である．手術時間は平均183分，術中出血量は平均644gであった．環椎歯突起間距離（ADI）は術前平均10.8mmが術後1.2mmと改善を認め，術後6カ月時のCTによる評価で5例全例に骨癒合が認められた．本法は環軸椎の強固な固定が期待でき，またMagerl法と比較してVA損傷の危険性が少ないなどの利点があり有効な固定法と思われる．

　Reports of atlantoaxial fixation with C1 lateral mass screws and C2 pedicle screws (C1LM-C2PS) have been published in recent years, but there have been few such reports in Japan. In the present study we evaluated 5 men and 1 woman with atlantoaxial subluxation who were surgically treated with C1LM-C2PS. The average operation time was 183min, and the average intraoperative blood loss was 644g. The average preoperative ADI value was 10.8mm, and improved to 1.2mm postoperatively, and fusion was confirmed by a CT evaluation. This method can provide rigid fixation of the atlantoaxial complex and has the advantage of little risk of injury to the VA in comparison with the Magerl method, and it appears to be effective.