Association Between Facet Joint Orientation and Degenerative Spondylolisthesis: A Radiological Study of Double-Level Versus Single-Level Degenerative Spondylolisthesis.

OBJECTIVE: To evaluate the correlation between lumbar degenerative spondylolisthesis (LDS) and facet joint orientation, and to examine the factors influencing facet joint orientation in patients with double-level LDS (dLDS). METHODS: A total of 40 patients with L3-5 dLDS (mean age, 64.1 years) and 106 patients with L4-5 single-level LDS (sLDS; mean age, 63.5 years) were included. Besides, 100 age-matched healthy participants were recruited as the control group. Facet joint angles at each level from L2-3 to L5-S1 were measured on axial computed tomogrpahy images. Slippage and spinopelvic sagittal parameters were measured using lateral full-spine x-rays. RESULTS: Both dLDS and sLDS groups had significantly larger facet joint angles from L2-3 to L5-S1 than those in the control group, except for left L5-S1. In patients with spondylolisthesis, the facet joint angles at the L2-3 and L3-4 levels in the dLDS group were significantly greater than those in the sLDS group, while the angles at the L4-5 and L5-S1 levels showed no significant differences. In contrast to the sLDS group, the dLDS group had significantly greater pelvic tilt, sagittal vertical axis, L3 slope, and L4 slope, as well as smaller sacral slope, lumbar lordosis, L3-4 disc height, L4-5 disc height, L4-5 slippage angle, and L3-S1 height. Age and dLDS were identified as independent factors influencing the changes in the L3-4 facet joint angles between the 2 LDS groups. CONCLUSION: Spondylolisthesis and aging are associated with facet joint sagittalization. The present study provides evidence that the combined effects of preexisting degeneration and spondylolisthesis alter the morphology of the facet joints.