RESUMO
BACKGROUND AND PURPOSE: Lumbar segmental instability (LSI) is a sub-group of non-specific low back pain (NSLBP), without any accepted diagnostic tool as a golden standard. Some authors emphasize on clinical findings, and others focus on vertebral translation and rotation, but construct validity of these measures had not been approved. Therefore, the purpose of the study was to evaluate convergent and known group validity of vertebral translation and rotation in differentiating LSI from NSLBP and control subjects. METHODS: Study variables included full-range and mid-range vertebral translation and rotation in sagittal plane. Five x-rays were taken in neutral, full flexion and extension and mid-flexion and mid-extension positions of lumbar spine. The variables were calculated using Computer Aided Radiographic Analysis of Spine (CARA) software after scanning. Sixty-six volunteered males participated in three groups. Twenty-two subjects were in the control group, and 44 NSLBP were divided into LSI and not LSI groups according to the criteria adopted by Hicks et al. The ANOVA and Tukey test were used in statistic analysis. RESULTS: ANOVA results demonstrated differences in three groups; for full-range translation and rotation, were not significant. However, the results of ANOVA demonstrated significant difference in L4-5 mid-range translation and rotation (p < 0/05). Tukey test showed significant difference for L4-5 mid-range translation between control (2.14 mm) and LSI (1.33 mm) groups (p < 0/05). Tukey test demonstrated difference between the control (14.18°) and LSI (11.65°) groups (p < 0/05); the control and not LSI (10.80) groups (p < 0/05) were significant for L4-5 mid-range rotation. CONCLUSIONS: On the basis of the study results, the full-range translation and rotation cannot differentiate LSI from not LSI and control groups. Moreover, the mid-range translation only differentiates control from LSI, whereas mid-range rotation differentiates control from both LSI and not LSI.
