Pedicle screw systemを用いて治療したMeyerding分類Ⅳ度の腰椎すべり症の3例

Meyerding Grade IV Lumbar Spondylolisthesis Treated with a Pedicle Screw System. Report of 3 Cases

　Meyerding分類Ⅳ度の第5腰椎すべり症の3例に対し，pedicle screw systemを用いた整復固定術(L5-S1)を行った．3例ともMeyerding分類Ⅰ度まで整復され，最終的に矯正損失なく骨癒合を得た．椎体の形成不全を伴い椎間可動性の少なかった1例で術後一過性の神経障害を認め，より慎重な整復操作が必要であったと考えた．一方，椎間不安定性が強く，短期間にすべりが進行した症例に対しては，神経根の十分な除圧と脊髄モニタリングを行うことで，可及的に整復操作を行えた．

　Posterior lumbar interbody fusion (L5-S1) with a pedicle screw system was performed to treat three cases of Meyerding grade IV lumbar spondylolisthesis.　Sufficient reduction to Meyerding grade I and bone fusion without correction loss were achieved in all three cases.　A postoperative neurogenic complication occurred in the one patient who had dysplastic vertebral deformities and poor intervertebral mobility, and more careful reduction may be necessary.　However, satisfactory reduction with adequate decompression of the nerve roots and monitoring of motor evoked potentials was achieved in both patients with marked intervertebral instability and rapid development of the vertebral slip.