頚椎後方拡大術後ハイドロキシアパタイトスペーサーの骨癒合評価

Evaluation of Bone Bonding of a Hydroxyapatite Spacer after Cervical Laminoplasty

　ハイドロキシアパタイト(HA)スペーサーを用いて頚椎後方拡大術を施行した26例を対象に，HAスペーサーの骨新生率と骨癒合率を評価した．術後平均3年でのHAスペーサーの骨新生率は97.1％，骨癒合率は64.4％であった．2回以上CTを施行できた群(9例)では，術後1年では骨新生率91.4％，骨癒合率28.6％であったが，術後3年では骨新生率97.1％，骨癒合率71.4％に増加していた．また，平均脊柱管拡大率は44.0～59.3％で，できる限り椎弓基部にHAスペーサーを設置することで，良好な骨癒合を獲得できた．

　We evaluated 26 patients with cervical myelopathy who underwent HA spacer-assisted laminoplasty to clarify bone bonding of HA spacer.　The average follow-up period was 3 years.　The bone regrowth rate of the HA spacer was 97.1% and the bone union rate was 64.4%.　In 9 patients whose postoperative CTs were available more than twice, time-dependent bone bonding was still observed after 3 years：i. e., the bone regrowth and union rates at 3 years after surgery (97.1% and 71.4%, respectively) were higher than those at 1 year after surgery (91.4% and 28.6%, respectively).　The mean spinal canal expansion rate (%) was 44.0－59.3%.　To settle the spacer as low as possible but with enough clearance to the dura yielded good bone-spacer bonding.