ObjectiveAlthough some studies have reported on the kinematics of the lumbar segments with degenerative spondylolisthesis (DS), few data have been reported on the in vivo 6 degree-of-freedom kinematics of different anatomical structures of the diseased levels under physiological loading conditions. This research is to study the in vivo motion characteristics of the lumbar vertebral segments with L4 DS during weight-bearing activities.MethodsNine asymptomatic volunteers (mean age 54.4) and 9 patients with L4 DS (mean age 73.4) were included. Vertebral kinematics was obtained using a combined MRI/CT and dual fluoroscopic imaging technique. During functional postures (supine, standing upright, flexion, and extension), disc heights, vertebral motion patterns and instability were compared between the two groups.ResultsAlthough anterior disc heights were smaller in the DS group than in the normal group, the differences were only significant at standing upright. Posterior disc heights were significantly smaller in DS group than in the normal group under all postures. Different vertebral motion patterns were observed in the DS group, especially in the left–right and cranial–caudal directions during flexion and extension of the body. However, the range of motions of the both groups were much less than the reported criteria of lumbar spinal instability.ConclusionThe study showed that lumbar vertebra with DS has disordered motion patterns. DS did not necessary result in vertebral instability. A restabilization process may have occurred and surgical treatment should be planned accordingly.
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