Radiographic Mensuration Characteristics of the Sagittal Lumbar Spine from a Normal Population with a Method to Synthesize Prior Studies of Lordosis

Standing lateral lumbar radiographs of 50 normal healthy subjects were retrospectively selected for evaluation of lumbar lordosis. The objective was to evaluate, in a normal population, global and segmental contributions to lordosis in the standing position, and to devise a method to compare the seemingly unrelated multitude of lordotic values in the literature. Because of a variety of positioning and measurement methods of lordosis in live subjects and cadavers, correlation of results is difficult. While often relying on simple pain questionnaires, studies of normal subjects rarely have complete medical history, physical, neurological, and orthopedic examinations. Standing lateral lumbar radiographs of 50 subjects, who had complete histories and normal examinations, were analyzed to determine overall lordosis, segmental contributions, and vertical sagittal alignment. Using posterior body tangents, the mean L1-L5 angle was -39.7 degrees, CobbT12-S1 = -65 degrees, Ferguson's sacral angle = 39 degrees, pelvic tilt angle was 49 degrees, and average RRAs (segmental angles) were RRAT12-L1 = -3.6 degrees, RRAL1-L2 = -4.1 degrees, RRAL2-L3 = -7.6 degrees, RRAL3-L4 = -11.7 degrees, RRAL4-L5 = -16.8 degrees, and RRAL5-S1 = -32.4 degrees. Using segmental rotation angles as a method to compare past and current literature, a normal standing lumbar lordosis of CobbT12-S1 = -61 degrees, range -55 degrees to -65 degrees, was determined with specific segmental angles.