筋肉温存型腰椎椎弓間除圧術の進入法を応用した胸椎黄色靱帯骨化症に対する除圧術

Posterior Decompression for Ossification of the Ligamentum Flavum by a muscle-preserving interlaminar decompression (MILD) Approach

　胸椎黄色靱帯骨化症(以下，OLF)に対して筋肉温存型腰椎椎弓間除圧術(以下，MILD)の進入法を応用した除圧術を施行した．対象は4例で，臨床成績と画像所見について検討した．1椎間あたりの出血量は平均41g，日本整形外科学会腰痛疾患治療成績判定基準(JOAスコア)の平均改善率は54％であった．骨化巣の高位や骨化形態に関わらず，術前計画通りに骨化巣の切除ができ，後弯の増大は平均2.2°で，矢状面アライメントに大きな影響を与えなかった．本術式は，出血が少なく，オリエンテーションが良好な広い術野で安全かつ十分に骨化巣の切除が可能であり，OLFに対する有用な低侵襲手術である．

　This study assessed posterior decompression by a muscle-preserving interlaminar decompression (MILD) approach as a means of treating ossification of the ligamentum flavum (OLF).　A midline incision was made, and the supraspinous ligament was split longitudinally.　The cranial and caudal edge of the OLF can be easily identified in the operative field, and the OLF can be accurately removed according to the preoperative evaluation (excision width) on computerized tomograms.　The clinical results and radiological assessments of four OLF patients were retrospectively reviewed.　Mean intraoperative blood loss was 41 g per segment.　The mean recovery rate according to the Japanese Orthopaedic Association (JOA) score was 54%, and the mean change in lordotic angle was 2.2 degrees.　The clinical outcome was satisfactory in all four cases.　We concluded that the bloodless, symmetrical, wide operative field allowed complete removal of the OLF and that this procedure is a safe and useful minimally invasive surgical procedure for the treatment of OLF.