- It is a common practice to the link low back pain with protruding disc even when neurological signs are absent. Because pain caused by sacroiliac joint dysfunction can mimic discogenic or radicular low back pain, we assumed that the diagnosis of sacroiliac joint dysfunction is frequently overlooked. To assess the incidence of sacroiliac joint dysfunction in patients with low back pain and positive disc findings on CT scan or MRI, but without claudication or objective neurological deficits. Fifty patients with low back pain and disc herniation, without claudication or neurological abnormalities such as decreased motor strength, sensory alterations or sphincter incontinence and with positive pain provocation tests for sacroiliac joint dysfunction were submitted to fluoroscopic diagnostic sacroiliac joint infiltration. The mean baseline VAS pain score was 7.8 +/- 1.77 (range 5-10). Thirty minutes after infiltration, the mean VAS score was 1.3 +/- 1.76 (median 0.000E+00 with an average deviation from median = 1.30) (P = 0.0002). Forty-six patients had a VAS score ranging from 0 to 3, 8 weeks after the fluoroscopic guided infiltration. There were no serious complications after treatment. An unanticipated motor block that required hospitalization was seen in four patients, lasting from 12 to 36 h. Sacroiliac joint dysfunction should be considered strongly in the differential diagnosis of low back pain in this group of patients.