Short Terms Effects of Medial Branch Block vs Para-spinal Muscle Injection in Patients With Non-specific CLBP

Inclusion Criteria: * CLBP of non-malignant origin fulfilling the following criteria: * Pain lasting for at least three months * Pain in both the left and right sides of the back * Pain below the L2 vertebral body * Lumbar spine CT scan or MRI done in the last 2 years * Average visual analogue scale (VAS) for pain ≥4/10 on each side for the 3 days * Cognitive and physical ability to provide informed consent in English or French Exclusion Criteria: * Neurologic signs or symptoms suggesting nerve root involvement * Strictly unilateral Low Back Pain (LBP) * CT scan or MRI findings suggestive of pain etiology beyond degenerative spine disease * Vascular malformations * Tumor * Infection * Fractures * DISH (Diffuse idiopathic skeletal hyperostosis) * Patients who have received injections of any type or acupuncture therapy to the low back in the last 3 months * Prior spine surgery * Local or systemic infection * Bleeding disorder or the use of anticoagulation medications but for low-dose aspirin * Known allergy to amid local anesthetics * Active insurance claim (CSST, SAAQ) * Uncontrolled psychiatric condition