Comparison of the Spinal Level Assumption by Palpation of the Iliac Crest and Posterior Superior Iliac Spine

ABSTRACT

OBJECTIVE: To compare the clinical usefulness of the posterior superior iliac spine (PSIS) with that of iliac crest (IC) for identifying the lumbar vertebral level. METHOD: Lumbar spine level was identified by the line connecting bilateral upper margin of iliac crests in the antero-posterior lumbar X-rays of 120 patients. Assumed IC level and assumed PSIS level were compared by 3 examiners' palpation in 60 patients. A marker was taped on assumed IC level and assumed PSIS level by 4 examiners and the postero-anterior lumbar X-rays was taken in randomly distributed 50 patients. RESULTS: IC intersection line was ranged from the L4 spinous process to the L5-S1 interspinous process in all patients. Inter- examiner agreement of palpation was significantly greater in PSIS than IC level (p<0.05). The marker indicating assumed IC level was higher than true IC level in all patients and was higher than L3-4 interspinous process in 8%. CONCLUSION: We may use PSIS level for assumption of the lumbar vertebral level to compensate for the limitation of iliac crest palpation, but at the same time keep in the mind the variarity of the PSIS level.