Retrospective Magnetic Resonance Imaging Evaluation in Patients with Zygapophysial Joint Pain

Objective: To assess the correlation between pain alleviation after medial branch blocks and changes seen in magnetic resonance imaging (MRI) in patients with zygapophysial joint pain in a retrospective practice audit. The diagnosis of zygapophysial joint pain is difficult, because neither history nor physical examination is able to identify a zygapophysial joint as pain source. Radiologic imaging can identify zygoapophyseal degeneration, however, this is also found in asymptomatic individuals.

Methods: Patients with pain suggestive of zygapophysial origin were tested with medial branch blocks. An independent radiologist, who was blinded for the patient’s symptoms and the symptomatic side, rated the MRI scans of every patient. Assessed were the orientation, the shape and the dimensions of the joint, the width and the signal of the joint gap and the grading of osteoarthritis.

Results: 36 patients were included, 26 patients were evaluated. There was no significant difference between the symptomatic side and the asymptomatic side in the 14 patients with positive response to the medial branch block (minimum 50% pain reduction). Comparing the symptomatic joints with joints of patients without zygapophysial joint pain, a difference in the orientation of the joint was striking. The angle of the symptomatic joints was larger (over 10° larger mean). Not all other parameters showed significant differences. In particular, the degenerative changes were similar in symptomatic and asymptomatic patients. The independent radiologist was able to determine the symptomatic side in only 57.1%.

Conclusions: MRI with the presented technology has no value as a diagnostic test for lumbar zygapophysial joint pain. Degenerative changes of the joints as detected by MRI do not correlate with zygapophysial joint pain. The statistic significant different orientation of symptomatic joints may point to a pre-existent risk factor.