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 sacroiliac 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 thorough 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 provocation tests'' is questioned.