Sacroiliac joint injection using the posterior superior iliac spines as landmarks: a preliminary study using cadavers

It is estimated that about 30% of cases of low back pain (LBP) are due to sacroiliac joint dysfunctions (SIJD). Accurate clinical diagnosis and treatment of LBP caused by SIJD is difficult without image guided techniques for needle placement into the sacroiliac joint cavity. Limitations in the availability of such image guided techniques in health institutions in developing countries are an obvious and major restriction, however the use of fundamental anatomic landmarks for surface marking of the sacroiliac joint for needle placement into the joint cavity is suggested as a useful substitute. Twelve adult cadavers (used for teaching) obtained from the Department of Anatomy, School of Medical Sciences, University of Science and Technology between 2006 and 2008 were studied. For each cadaver, the gluteal region was dissected to expose the bony posterior superior iliac spines (PSIS) and the posterior long sacroiliac ligaments. The proximal third of both posterior long sacroiliac ligaments were removed to expose the clefts between the two bones on both sides for the introduction of an IV cannula introducer needle 24G (Suruflon, Suru International PVT, Ltd, Mumbai) into the cleft between the two bones inferior to PSIS and advanced in a direction where the penetration was without resistance. A second needle was placed perpendicularly at the PSIS and radiographs of the posterioanterior view of the cadaveric pelvis were taken to confirm the placement of the needle in the sacroiliac joint, using Turdde 38 mobile X-ray machine. The needle position from the posterior superior iliac spine and its angle of inclination from the para-sagittal plane were measured. The data was analyzed using graph pad prism. The position of the needle ranged from 2 to 3.7 cm inferior to PSIS in all the cadavers with a mean of 2.52 cm (SE 0.09) for right and 2.59 cm (SE 0.20) for left. There was no significant difference between the right and the left needle positions of the joint (paired t-test, p>0.05). The angle of inclination of the needle ranged from 10o to 30o medial to the parasagittal plane with a mean of 24.58o (SE 2.2) and 25.12o (SE 1.8) for right and left respectively. These results show that an IV cannula introducer needle placed at 2-3 cm inferior to PSIS and directed at angle of 20-30o medial to the para-sagittal plane would get into the synovial part of the sacroiliac joint and confirms the intra-articular needle position within the sacroiliac joint using the PSIS as the anatomic landmark. These quantitative data present baseline values forfurther clinical investigation