The Prevalence of "Pure" Lumbar Zygapophysial Joint Pain in Patients with Chronic Low Back Pain.

BACKGROUND Estimates of the prevalence of lumbar zygapophysial joint (Z joint) pain differ in the literature, as do case definitions for this condition. No studies have determined the prevalence of "pure" lumbar Z joint pain, defined as complete relief of pain following placebo-controlled diagnostic blocks. OBJECTIVE The objective of this study was to estimate the prevalence of "pure" lumbar Z joint pain. METHODS In a private practice setting, 206 patients with possible lumbar Z joint pain underwent controlled diagnostic blocks using one of two protocols: placebo-controlled comparative blocks and fully randomized, placebo-controlled, triple blocks. RESULTS In the combined sample, the prevalence of "pure" lumbar Z joint pain was 15% (10-20%). CONCLUSIONS The prevalence of "pure" lumbar Z joint pain is substantially and significantly less than most of the prevalence estimates of lumbar Z joint pain reported in the literature.