To determine the prevalence of pain arising from the zygapophysial joint in patients with chronic low back pain and to determine whether any clinical features could distinguish patients with and without such pain.
Sixty three patients with chronic low back pain were studied prospectively. All patients underwent a detailed history and physical examination as well as a series of intra-articular zygapophysial joint injections of 0.5% bupivacaine starting at the symptomatic level to a maximum of three levels or until the pain was abolished. They also received injections of normal saline into paraspinal muscles to act as controls.
All patients proceeded with the injections. Twenty (32%; 95% confidence interval (CI) 20 to 44%) obtained greater than 50% relief of their pain following the administration of saline. Fifty seven patients completed the study; 23 of them (40%; 95% CI 27 to 53%) failed to obtain relief following the injection of saline but obtained relief following one or more intra-articular injections of local anaesthetic. None of the historical features or clinical tests could discriminate those patients with and those without zygapophysial joint pain.
Pain originating from the zygapophysial joint is not uncommon, but this study failed to find any clinical predictors in patients with such pain.