Lumbar lordosis in prone position and prone hip extension test: comparison between subjects with and without low back pain.

BACKGROUND: Prone hip extension (PHE) is a common and widely accepted test used for assessment of the lumbo-pelvic movement pattern. Considerable increased in lumbar lordosis during this test has been considered as impairment of movement patterns in lumbo-pelvic region. The purpose of this study was to investigate the change of lumbar lordosis in PHE test in subjects with and without low back pain (LBP).

METHOD: A two-way mixed design with repeated measurements was used to investigate the lumbar lordosis changes during PHE in two groups of subjects with and without LBP. An equal number of subjects ( N  = 30) were allocated to each group. A standard flexible ruler was used to measure the size of lumbar lordosis in prone-relaxed position and PHE test in each group.

RESULT: The result of two-way mixed-design analysis of variance revealed significant health status by position interaction effect for lumbar lordosis ( P  < 0.001). The main effect of test position on lumbar lordosis was statistically significant ( P  < 0.001). The lumbar lordosis was significantly greater in the PHE compared to prone-relaxed position in both subjects with and without LBP. The amount of difference in positions was statistically significant between two groups ( P  < 0.001) and greater change in lumbar lordosis was found in the healthy group compared to the subjects with LBP.

CONCLUSIONS: Greater change in lumbar lordosis during this test may be due to more stiffness in lumbopelvic muscles in the individuals with LBP.