Objective: To observe the in vivo vertebral motion of adjacent segments in patients with degenerative spondylolisthesis (DS) during functional weight-bearing activities.
Methods: A total of 15 symptomatic L4 DS patients (mean age 54.4 years) and 15 asymptomatic volunteers (mean age 53.4 years) were recruited. The vertebral segment motion of each subject was reconstructed with three-dimensional computed tomography and solid modeling software. In vivo lumbar vertebral motion during functional postures (flexion-extension, left-right twisting and left-right bending) was observed with dual fluoroscopic imaging. Coordinate systems were established at the vertebral center of L3-S1 to obtain the intervertebral range of motion (ROM) at L3/4, L4/5 and L5/S1 in DS and normal groups.
Results: The motion pattern at L3/4 with DS was altered. During left-right bending, the rotation along sagittal axis was significantly larger than normal group (4.4° ± 2.8° vs 2.1° ± 1.7°, P < 0.05). During left-right twisting, the rotation along vertical axis was significantly larger than normal group (4.3° ± 2.8° vs 2.1° ± 1.3°, P < 0.05). During flexion to extension, the rotation along frontal axis was larger than DS group (3.9° ± 3.3° vs 3.2° ± 2.5°). However the difference was insignificant. The motion pattern at L4/5 and L5/S1 with DS had no significant difference with normal group.
Conclusion: The slipped segments of degenerative spondylolisthesis are stable. However, the ROM of cranial segment increases.