Analysis of the Sagittal Alignment of Normal Spines

Lee, Chong Suh; Oh, Won Hwan; Chung, Sung Soo; Lee, Saeng Guk; Lee, Jong Yoon

Abstract

PURPOSE: This study was undertaken to increase the knowledge of the intra- and extra-spinal alignments and to help recovery of sagittal alignment in operation by measuring the normal values of the spinal alignment in relation to hip axis as well as those of the thoracic, thoracolumbar junction, lumbar and lumbosacral junction of sagittal alignment and their correlation.
MATERIALS AND METHODS
Whole spine standing lateral radiographs were taken in young 100 adults without spinal abnormalities clinically and radiographically. Intraspinal alignment was measured with angles of thoracic kyphosis, lumbar lordosis, maximum thoracic kyphosis, maximum lumbar lordosis, angle of the thoracolumbar junction, sacral inclination, segmental angles and disc angles respectively with special emphasis on lumbar lordosis. Extraspinal alignment was measured with sacropelvic angle, spinopelvic balance and spinal balance in relation to hip axis. Correlations among these parameters were analyzed.
RESULTS
Lumbar lordosis and thoracic kyphosis were measured -49 degree(-22 - -79 degree) and 32 degree(6 degree-56 degree), respectively. Slight amount of kyphosis in thoracolumbar junctional area was considered normal. Lumbar lordosis had significant correlation with thoracic kyphosis and sacral inclination. However, there was no correlation between thoracic kyphosis and sacral inclination. Lowest two lumbar segments comprised 71% of total lordosis. Lumbar lordosis usually started at L1-2 and gradually increased at each level caudally to the sacrum. Sacropelvic angle, spinopevlic balance and spinal balance were measured -11 degree(-6 degree - 24 degree), -4 cm (-10 - 2 cm), and -2 cm (-7 - 4 cm) respectively with C7 positioned posterior to hip axis mostly.
CONCLUSIONS
There was a wide range of normal sagittal alignment of the thoracic and lumbar spines, and normal values of these alignments were not easily defined. Therefore, normal patterns of sagittal curvature and sagittal balance should be more emphasized.