腰椎後方進入椎体間固定術後ケージ脱転例の検討

Evaluation of Retropulsion of the Cage after Posterior Lumbar Interbody Fusion

　当院で腰椎変性疾患に対して腰椎後方進入椎体間固定術を施行した1,070例中，ケージが脱転した9例(男性7例，女性2例)から，そのリスクファクターについて検討した．平均年齢は68歳，後側方固定術も併用した固定椎間数は平均3.9椎間，術前の平均椎間板高は11.9mm，平均椎体間可動域は10.7°で，9例中6例がL5/S脱転例であった．L5/S，椎間板高が高く椎間可動域の大きい洋梨状の椎間板形状，多椎間固定の末端椎間がリスクファクターと考えられ，これらを有する症例にはケージ選択も含めて注意を要する．

　We evaluated the 9 cases (7 males and 2 females) of cage retropulsion after posterior lumbar interbody fusion (PLIF) among the 1,070 cases of lumbar degenerative disease treated by PLIF with posterolateral fusion in our hospital.　Average age at surgery was 68.2 years, and the average fusion level was 3.9.　In most of the cases the cage retropulsion occurred within 1 month after surgery, and the level involved was L5/S in 6 patients, L4/5 in 2 patients, and L3/4 in 1 patient.　The average disc height was 11.9 mm, and the average disc angle was 10.7 degrees.　Five patients experienced leg pain, and 3 of them required additional surgery, but the other 2 patients did not experience any symptoms.　These results suggested that L5/S, high disc space with instability, and multiple fusion surgery are risk factors for cage retropulsion after PLIF.