Reliability of the attraction method for measuring lumbar spine backward bending.

The distraction method is one method used to measure forward bending of the spine. Although this technique, which requires the use of a tape measure held over the spine and the location of anatomical landmarks, appears to be highly practical, previous studies have not examined its use for measuring backward bending. The purpose of our study was to determine the reliability of a similar technique, the attraction method, for measuring backward bending of the lumbar spine and to examine whether subjects with low back pain (LBP) could perform similar motion as subjects without LBP. Two groups composed of 100 subjects each, one with "significant" limiting low back pain (SLBP) and the other without "significant" limiting low back pain (NSLBP), were evaluated twice by a physical therapist to assess intrarater reliability. To assess interrater reliability, 11 subjects from the NSLBP Group were evaluated by a second therapist. For the total sample of 200 subjects, the intraclass correlation coefficient (ICC) for intrarater reliability was .95; for the SLBP Group, the ICC was .93; and for the NSLBP Group, the ICC was .90. For the sample of 11 NSLBP Group subjects examined for interrater reliability, the ICC was .94. Using a Kolmogorov-Smirnov test, we found the distribution for backward bending of the two groups to be significantly different. The attraction method, thus, appears to be a reliable method for measuring backward bending of the lumbar spine.