Accuracy of measuring lateral flexion of the spine with a tape.

Tape measurement of spinal lateral flexion from the erect posture as the distance the hand moves down the thigh was analysed. Intra- and interobserver reproducibility were found to be acceptable (r=0·74-0·96). Correlations of the measurements with an index of low-back pain and with inclinometric measurements of pelvic, lumbar and thoracic mobility were calculated for 476 patients suffering from low back pain. The correlation coefficients of the tape measurements with the total inclinometric measurements of pelvic and thoracolumbar mobility were 0·63 and 0·64. For spinal mobility alone the corresponding coefficients were 0·48-0·50 for the lumbar spine, and 0·58-0·59 for the thoraco-lumbar spine. The correlation coefficients between the method using tape measurement and the index of low back pain were -0·23 and -0·25 (P<0·001). Lateral flexion of the lumbar spine alone, measured inclinometrically, had correlation coefficients of -0·11 and -0·17 (P<0·05 and 0·001) with low back pain. According to the inclinometric measurements, pelvic and thoracic spinal mobility were also related to the degree of low back pain, which probably improves further on the tape measurement method as an indicator of low back disability.