Lumbar Spinal Fibrosis and TNF Alpha Inhibition

Inclusion Criteria: * age over 18 years old * sciatica post discectomy * Pain with VAS \> 40 mm and impossibility to have his usual activity * Surgical discectomy (less than 2 years and more than 6 months) * Painless of more than one month and less than one year after the discectomy * MRI with gadolinium injection of less than 6 months and done more than 6 months after the discectomy * Presence of spinal fibrosis on MRI (hyposignal in T1 enhanced by gadolinium and hypersignal in T2) * failure of epidural injection treatment * absence of tuberculosis * contraception for woman * informed consent Exclusion Criteria: * Chronic psychiatric pathologies not treated * Presence of conflict between nerve root and herniated disc or disc fragments or spinal stenosis * severe cognitives troubles * severe cardiac failure (class III or IV) * Tuberculosis (active or latent), severe infections * Cancers * Allergy reactions to the drug studied * Difficulties to understand french * Patients enrolled in another clinical trial in the past three months * pregnancy, breastfeeding or no contraception