感染性脊椎炎に対するリン酸カルシウムセメントの応用―抗菌剤の徐放性キャリアとしての使用例

Local Antibiotic Treatment for Vertebral Osteomyelitis Using Calcium Phosphate Cement. Case Report

　抄録：非定型抗酸菌性脊椎炎に対し，抗結核剤の徐放性キャリアとしてリン酸カルシウムペースト（以下CPC）を使用した症例について報告する．症例は81歳女性で，腰痛と右下肢痛のため歩行困難となり，右大腿神経麻痺を呈していた．MRIにてL2/3椎間腔の狭小化と椎体の骨破壊像，硬膜外膿瘍を認め，針生検にてMycobacterium Kansassiiが検出された．前方および後側方固定術を一期的に施行した．前方固定にはINH 450mgを混合したCPCをチタンメッシュ内に充塡して使用し，後側方固定ではインストゥルメンテーションを併用した．術後，硬性コルセットを6カ月間装着し，INH・RFP・EBの抗結核剤3剤の内服投与を9カ月間行った．術後1年6カ月の経過観察時，骨癒合は得られ，感染の再燃も認めなかった．抗結核剤の徐放性キャリアとしてのCPCと前方支柱としてのチタンメッシュの併用は有用な方法として期待される．

　This is a report of a case in which antibiotic therapy with calcium phosphate cement (CPC) was used to treat mycobacterial vertebral osteomyelitis. An 81-year-old woman with L2-L3 spondylodiscitis and associated epidural abscess developed severe low back and paraparesis. Imaging studies, including MRI and CT scans, showed irregular erosion and narrowing of the disc space and vertebral body destruction at L2-L3. A CT-guided needle biopsy revealed vertebral osteomyelitis caused by Mycobacterium Kansassii, and anterior decompression and circumferential spinal reconstruction were performd. The anterior procedures included curettage of the deteriorated disc and vertebral bone followed by fusion with titanium mesh injected with a mixture of calcium phosphate cement and an anti-mycobacterial agent (isoniazid, 450mg). Posterolateral fusion was performed with an iliac bone graft and posterior screw-hook instrumentation. Parenteral anti-mycobacterial therapy with isoniazid (INH), rifampin (RFP), and ethambutol (EB) was performed on a 9-month regimen. At the 18-month follow-up, solid arthrodesis had been achieved with no recurrence of the infection. CPC is an osteoconductive paste for injection into vertebral cages, and it is expected to release antibiotic agents slowly after consolidation.