Facet Joint Orientation and Sagittal Spinopelvic Alignment in Patients with Degenerative Lumbar Scoliosis

The purpose of this study was to evaluate the association between lumbar spine facet joint orientation and tropism, sagittal spinopelvic alignment, and rotational deformity, identified by radiographic and computed tomography (CT) measurements, in degenerative lumbar scoliosis (DLS). Standing whole-spine sagittal radiographs and CT scans, including the pelvis, were performed and analyzed in 60 DLS patients (16 males, 44 females; mean age 65 years). Cobb angle, pelvic incidence (PI) and lumbar lordosis (LL) were measured on standing lumbar radiographs. Facet joint orientation on both sides at L3/4, L4/5, and L5/S1 was determined from transverse-plane CT. Facet joint tropism was defined as a difference in symmetry of more than 10 degrees between the orientations of the facet joints. There were significant differences in the incidence of facet joint tropism between the two groups at L3/4, L4/5, and L5/S1 (P = 0.011, P = 0.043, and P = 0.004, respectively). LL was significantly smaller in type II DLS (P = 0.049). Facet joint orientation, pelvic incidence, and Cobb angle did not differ between groups. No significant correlation between LL and PI was observed in either group. This study provides a reliability analysis of rotational deformity in patients with DLS. In conclusion, we observed a significant relationship between facet joint tropism and rotational deformity in patients with DLS. Furthermore, the different types of DLS demonstrated significant differences in LL that may induce spinal symptoms.