腰椎形成不全性すべり症に対する椎弓根スクリュー法の治療成績

Surgical Outcomes of Pedicular Screw Fixation for Lumbar Dysplastic Spondylolisthesis

　目的：腰椎形成不全性すべり症に対する腰仙椎固定術の治療成績について報告する．対象および方法：対象は手術的治療を行ったMeyerdingⅡ度およびⅢ度のすべりを呈する14例（男2例，女12例，平均年齢20.7歳，追跡調査期間44.2カ月）であった．手術は全例に椎弓根スクリューを用い，椎体間固定術を行った．L4を固定範囲に含め2椎間固定を行った症例が8例（A群），L5-S1の1椎間で整復固定を行った症例が6例（B群）であった．検討項目は1）手術成績，2）X線所見，3）手術時間と術中・術後合併症とした．結果：1）JOAスコア改善率はA群77.4±9.8％，B群79.9±14.5％と両群間に有意差はなかった．2）骨癒合は全例で得られた．％ slip矯正率はA群56.3％，B群70.4％であったが，有意差はなかった．腰仙椎の前弯度を示すdelta angleの矯正率はA群6.4％，B群39.7％で，B群で有意に良好であった（p＜0.05）．3）手術時間はA群427分，B群280分，出血量はA群731g，B群352gで，いずれもB群で有意に低値であった．合併症はスクリュー折損・back-out 2例，一過性下垂足1例，表層感染2例であった．考察および結語：形成不全性すべり症に対する椎弓根スクリューを用いた整復固定術ではB群ではA群と比較してより良好な整復が得られ，かつ手術時間，出血量が少なかった．本研究で対象としたMeyerding Ⅲ度までのすべりであれば，単椎間固定で対応可能と考えられた．

　Objective：The outcome of treatment of lumbar dysplastic spondylolisthesis by fixation of the lumbosacral spine is described. Subjects and Methods：The subjects were 14 patients with Meyerding grade Ⅱ or Ⅲ dysplastic spondylolisthesis (2 males and 12 females, mean age 20.7 years；mean follow-up period 44.2 months) who were treated surgically. Pedicular screw fixation and interbody fusion were performed in all patients. Two-level fusion from L4 to S1 was carried out in 8 patients (group A), and the other 6 patients underwent single-level fusion at L5-S1 (group B). The items assessed were 1) surgical outcome and 2) radiographic findings, 3) operation time and complications. Results：1) The JOA score recovery rate was 77.4％ in group A and 79.9％ in group B, (NS.) 2) Bone union was achieved in all patients. The correction rate of percentage slip was 56.3％ in Group A and 70.4％ in Group B. The mean delta angle correction rate was 6.4％ in group A and 39.7％ in group B, and it was significantly higher in group B (p＜0.05). 4) Mean operation time was 427 minutes in group A and 280 minutes in group B (p＜0.05), and mean blood loss was 731g in group A and 352g in groupB (p＜0.05). Discussion：Improvement of clinical symptoms with good reduction of spondylolisthesis and bone union were obtained. More favorable reduction with a shorter operation time and smaller blood loss was obtained in group B than in group A. Based on these results, Meyerding grade Ⅱ and Ⅲ dysplastic spondylolisthesis can be treated by single-level interbody fusion using pedicular screw fixation.