[The apparent parallelism of L5-S1 as an early radiologic sign of lumbo-sacral disk herniation].

The purpose of ths study was to confirm the authors' impression of parallel margins between the lower vertebral plate of the last lumbar vertebra and the upper plate of the first sacral vertebra in patients suffering from herniation of the last disc. The study involved 3 groups of patients: the first comprised patients with sciatica due to compression of the S1 nerve root, the second group consisted of normal subjects and the third included patients suffering from low back pain without disc pathology. The results show that a parallel appearance between the L5 ad S1 vertebral bodies was apparent for angles of lambda less than or equal to 10 degrees. The authors have found these parallel margins only in patients suffering from disc herniation between L5 and S1.