Quantitative ultrasound assessment of the facet joint in the lumbar spine: a feasibility study

This study was designed to determine the feasibility and accuracy of a sonographic approach to assessment of facet joints of the lumbar spine in healthy populations. Five facet joints (L1-S1) on each side of 30 volunteers, for a total of 300 facet joints, were examined and evaluated by sonography and computed tomography. Parameters of the facet joints (height and width) were established to assess the facet joint in the parasagittal and transverse planes on all volunteers. Differences between means of continuous variables including age, height, weight, body surface area, body mass index and joint parameters were evaluated with Student's t-test. Stepwise multiple regression analysis was used to evaluate the associations between the mean values of facet joint parameters and age, height, body surface area and body mass index. In general, sonography revealed that facet joints had a clear and smooth border. There were no significant differences in width and height between the left and right facet joints at the same level by sonography. Stepwise multiple regression analysis revealed that body mass index and age (p < 0.05) were the only independent factors modulating height of the facet joint. Facet joint width was independently influenced by age (p < 0.01). There were no significant differences between ultrasound and computed tomography in mean measurements of height (1.23 ± 0.15 vs. 1.25 ± 0.07, p > 0.05) and width (0.17 ± 0.08 vs. 0.18 ± 0.07, p > 0.05) of the facet joint, respectively. In this article, we describe a feasible, accurate and simple technique for identification and depiction of facet joints of the lumbar spine in healthy populations.