Results of sacroiliac joint double block and value of sacroiliac pain provocation tests in 54 patients with low back pain.

STUDY DESIGN: This prospective study consisted of the evaluation of a double sacroiliac block in patients with low back pain.

OBJECTIVES: To determine the prevalence of sacroiliac pain in a selected population of patients suffering from low back pain, and to assess certain pain provocation tests.

SUMMARY OF BACKGROUND DATA: Previous studies have implicated the sacroliac joint as a potential etiology of back and leg pain, but none has tested double anesthetic blocks in a prospective fashion.

METHODS: Fifty-four patients with unilateral low back pain, pain mapping compatible with a sacroiliac origin, tenderness over the sacroiliac joint, and no obvious source of pain in the lumbar spine were selected for a double anesthetic block. The procedure consisted of a through clinical examination with a visual analog scale, testing of sacroiliac pain provocation tests followed by a first screening block with a short-acting anesthetic. A second examination consisting of the same tests assessed the efficacy of the first block. If results were positive, a confirmatory block was performed. All blocks were performed under fluoroscopic guidance.

RESULTS: Nineteen patients had a positive response to the first block. Among them, 10 (18.5%) were temporarily relieved by the confirmatory block. No pain provocation test reached statistical significance.

CONCLUSION: The present study suggests the sacroiliac joint is an uncommon but real source of low back pain. The accuracy of some of the presumed "sacroiliac pain provocations tests" is questioned.