Study Design. Retrospective clinical study.
Objective. The purpose of this study was to examine the changes in spinopelvic alignment after interspinous soft stabilization (ISS) with a tension band system and to identify the lumbosacral parameters related to those changes and to determine their impact on the clinical outcomes compared with posterior lumbar interbody fusion (PLIF) in patients with low-grade degenerative spondylolisthesis (DS).
Summary of Background Data. The sacropelvic morphometric changes after fusion surgery have received much research attention. However, few reports have addressed the issue after use of dynamic or soft stabilization systems.
Methods. From April 2001 to November 2003, 45 patients presenting with grade 1 DS with stenosis underwent either ISS with a tension band system (ISS group) or PLIF with pedicle screw fixation (PLIF group). The mean follow-up period was 76.8 months. Three pelvic parameters, the sacral slope (SS), pelvic tilt (PT), and pelvic incidence, were investigated to address the sacropelvic morphometric change. Clinical outcomes were assessed using the visual analog scale score, the Oswestry Disability Index, and the patient's satisfaction index.
Results. Both groups showed significant improvements in all of the clinical outcomes, with no significant differences between groups. In the ISS group, the SS increased and PT decreased, whereas in the PLIF group, the SS decreased and PT increased, resulting in pelvic anteversion and retroversion, respectively, with significant intergroup differences in SS and PT (SS: P = 0.047; PT: P = 0.01). The positive association of lumbar lordosis with SS (r = 0.448) and its negative association with PT (r = −0.674) in the respective groups indicate the influence of changes in lumbar lordosis on pelvic positional changes. Significant correlations between follow-up segmental lumbar lordosis and the visual analog scale score for leg pain (r = −0.685) and Oswestry Disability Index score (r = −0.425) were found in the ISS group alone.
Conclusion. Segmental lordotic change after ISS with a tension band system was the possible decisive factor in the development of pelvic anteversion while maintaining sagittal lumbar balance; lack of lumbar lordosis led to compensatory pelvic retroversion in the PLIF group. Considering the comparable clinical results with PLIF surgery and the achievement of physiologic sagittal spinopelvic balance, the ISS procedure can be a feasible alternative to fusion surgery in patients with grade 1 DS with stenosis.
Segmental angular changes resulted in the pelvic anteversion and retroversion in interspinous soft stabilization (ISS) and posterior lumbar interbody fusion (PLIF) groups, respectively. Considering the comparable results with PLIF surgery and achievement of physiologic sagittal spinopelvic balance, ISS can be a feasible alternative to fusion surgery in patients with grade 1 degenerative spondylolisthesis with stenosis.
From the Departments of *Neurosurgery, †Orthopedics, and ‡Radiology, Wooridul Spine Hospital, Seoul, South Korea; and §Wooridul Institute for Biomedical Science and Technology, Seoul, South Korea.
Acknowledgment date: July 10, 2009. First revision date: October 23, 2009. Second revision date: December 10, 2009. Acceptance date: December 16, 2009.
The device(s)/drug(s) that is/are the subject of this manuscript is/are not FDA-approved for this indication and is/are not commercially available in the United States.
Funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Supported by a grant from Wooridul Spine Foundation.
Address correspondence and reprint requests to Ho-Yeon Lee, MD, PhD, Department of Neurosurgery, Wooridul Spine Hospital, 47-4 Cheongdam-Dong, Gangnam-Gu, Seoul 130-100, South Korea; E-mail: firstname.lastname@example.org