Subjects (N=120) who have had non-radicular low back pain, believed by clinical assessment and imaging to be consistent with lumbar zygapophysial joint (Z-joint) generated pain, who have failed conservative therapy including physical therapy, have had an initial >80% pain relief on a diagnostic medial branch block, and are scheduled to undergo a routine second medial branch block for facet mediated pain will be randomized. Both groups will receive the standard of care, a medial branch block. The treatment group will also receive one set of intra-articular lumbar Z-joint corticosteroid injection and the placebo group will receive intra-articular normal saline.