A study of how intervertebral angles were distributed in two asymptomatic control groups—those who would develop lower back pain (LBP) after prolonged standing, and those who did not develop pain—found that there was a correlation between the distribution of intervertebral angles in pain developers (PD) throughout lumbar spines during upright standing poses, while there was little difference in the amount of lumbar lordosis, range of motion, lumbar spine recurve, or lumbar vertebral wedging between the two groups.

The Study

Eight subjects from a previous study were recruited for the purposes of characterizing lumbar postures in PDs and non-pain-developers (NPD). Researchers wished to find out how the distribution of intervertebral angles differed in both groups during standing x-rays. The study also looked at the range of motion (ROM) and various lumbar vertebral characteristics in members of each group. Eight male and female PDs were compared with eight male and female NPDs. PDs had reported developing LBP after two hours of standing in the previous study. An x-ray technician used a diagnostic high voltage x-ray generator to create radiographs of each participant during three static poses: upright standing, full extension, and full flexion. Measurements were made to determine each subject’s intervertebral angles as they related to each other and to the superior endplate and inferior vertebrae. The person responsible for analyzing the measurements was blinded to the pain groups until all the variables had been computed, and statistical models were created using SAS, with dependent variables grouped by Pose. The data was later analyzed, where statistically significant.


Overall, those in the NPD study group had L5/S1 angles that were significantly more extended than their L1/L2, L2/L3, or L3/L4 angles. In addition, their L4/L5 angles were more extended than their L1/L2 angles. Those in the PD group were less varied and only showed differences between L1/L2 and L5/S1 with extension. For the most part, the two pain groups showed little variation in ROM, lumbar lordosis, vertebral wedging, or recurve, though subjects in the PD group did have a more equitable distribution of intervertebral angles throughout their lumbar spines in standing and full extension poses. PDs did not exhibit more lumbar lordosis while standing, but they were more likely to be recognized by their rate of extension during upright standing poses. This indicates that the overall lumbar spine characteristics of PDs and NPDs are similar, though they vary regionally when in extended poses. Therefore, it may be useful to use fully extended postures when identifying PDs versus NPDs in radiographic studies.

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