Roentgenographic evaluation of lumbar spine flexion-extension in asymptomatic individuals.

An experimental clinical study of angulatory and translational lumbar spine intervertebral motion was performed using flexion-extension radiographs obtained in the lateral plane. These "bending" films were obtained from 59 asymptomatic individuals undergoing routine pre-employment examination. Results indicate that there is 7 to 14 degrees of angulatory motion present in the lumbar spine but a large range of values exist so that norms of angulatory motion cannot be more precisely defined. There are 2 to 3 mm of translational motion present in the lumbar spine at each intervertebral level. Twenty percent of this study's asymptomatic subjects had 4 mm or more translational motion at the L4-5 interspace and at least 10% had 3 mm or greater motion at all levels except L5-S1. These results challenge conclusions based on earlier studies and call into question the use of lumbar flexion-extension bending films as a primary determinant of lumbar segmental stability.