AN ANALYSIS OF SAGITTAL SPINAL ALIGNMENT IN 100 ASYMPTOMATIC MIDDLE AND OLDER AGED VOLUNTEERS

Study Design. A radiographic evaluation of 100 adult volunteers over a ge 40 and without a history of significant spinal abnormality was done to determine indices of sagittal spinal alignment. Objectives. To det ermine the sagittal contours of the spine in a population of adults ol der than previously reported in the literature and to correlate age an d overall sagittal balance to other measures of segmental spinal align ment. Summary of Background Data. Previous studies of sagittal align m ent have focused on adolescent and young adult populations before the onset of degenerative changes that may affect sagittal alignment. Meth ods. Radiographic measurements were collected and subjected to statist ical analysis. Results. Mean sagittal vertical axis fell 3.2 +/- 3.2 c m behind the front of the sacrum. Total lumbar lordosis (T12-S1) avera ged -64 degrees +/- 10 degrees. Lordosis increased incrementally with distal progression through the lumbar spine. Lordosis at L5-S1 and the position of the apices of the thoracic and lumbar curves were most cl osely correlated-to sagittal vertical axis. Increasing age correlated to a more forward sagittal vertical axis with loss of distal lumbar lo rdosis but without an increase in thoracic or thoracolumbar kyphosis. Conclusions. The majority of asymptomatic individuals are able to main tain their sagittal alignment despite advancing age. Loss of distal lu mbar lordosis is most responsible for sagittal imbalance in those indi viduals who do not maintain sagittal alignment. Spinal fusion for defo rmity should take into account the anticipated loss of lordosis that m ay occur with age.