[Pain and functional disturbances in the sacroiliac joint in disc herniation of the lower lumbar spine.].

Back and leg pain in patients with lumbar disc herniation can be caused by various mechanisms. In addition to nerve root compression, functional alterations in the sacroiliac joint, facet joint or the iliolumbar and sacrotuberal ligaments can produce "pseudoradicular" lower back syndrome. The following study attempts to show whether or not pain and functional alterations in the sacroiliac joint (SIJ) correlate with herniations revealed by computed tomography (CT). The study also attempts to determine the correlation between pain and functional changes of the SIJ and the size and level of the disc herniation. Fifty patients with monosegmental disc herniations revealed by CT who showed no signs of bone or soft tissue alterations were included in this study. The average duration of the patients' complaints of leg or back pain was 5.7 years. Ninety-six percent of these patients had received conservative treatment before admission to our hospital. All patients were compared to a control group consisting of 16 healthy subjects of comparable age. All patients underwent a comprehensive functional, neurologic and radiologic examination. The CTs were analyzed by a standardized three-dimensional method. All of the 50 patients had sciatica complaints and a disc herniation revealed by CT. In two cases hemiation of the L3-4 disc was demonstrated, in 14 cases L4-5 disc herniation and in 34 cases a L5-S1 disc herniation. In contrast to the control group of 15 healthy subjects, the patients showed a significant number of functional disorders upon examination. In 84% of all patients, movement of the SIJ was restricted. Painful palpation of the symphysis was demonstrated in 46% of all cases. Thirty-five percent of patients with herniation of L4-5 disc demonstrated SIJ tenderness as opposed to 65% of the patients with herniation of the L5-S1 disc. This SIJ tenderness did not correlate with motion of the SIJ. In addition, SIJ motion and frequency of sensory dysfunction showed no correlation with the size of the disc herniation. Paralysis and loss of reflexes showed a positive correlation with the increasing size of the disc herniation. SIJ tenderness decreased as the size of the herniation increased. Dysfunction of the ipsilateral SIJ is explained by increased muscular tone caused by irritation of the n. sinuvertebralis and its lumbar coupling. Frequency of SIJ tenderness is significantly higher in patients with herniations between L5 and S1. Since the SIJ is innervated by the r. dorsalis of the sacral roots, the increased tenderness can be explained by the change in neurovegetative innervation of the SIJ. Due to the high correlation between lumbar disc herniation and SIJ dysfunction, disc herniation should be considered as a possible cause of sacroiliac-joint syndrome.