Ultrasound-Guided Thermocoagulation of Medial Nerve Branch in Lumbar Facet Joints Pain.

Inclusion Criteria: * Over the age of 18. * Facet Syndrome. * Symptomatology superior than 3 mounths. * A failure of conservative treatement (drugs, physiotherapy...) * Partial improvement after two lumbar facet infiltrations. Exclusion Criteria: * Allergy to any of the constituents of the infiltrated product, or to the contrast medium * Unstable medical condition: cardiac, respiratory, endocrine (uncontrolled diabetes) * Local infection (cutaneous, perimedullary / spinal) or systemic. * Coagulopathy (platelets \<50000 / mm3, Prothrombin time \<60%, INTernational normalized ratio\> 1.5), anticoagulant or antiplatelet therapy treatment other than aspirin. * Lumbar arthrodesis. * Neurological condition affecting motor function (Stroke, Parkinson...) * Pregnant woman.