Journal article
Biomechanical evaluation of occipitocervicothoracic fusion: impact of partial or sequential fixation
The spine journal, v 8(5), pp 821-826
01 Sep 2008
PMID: 17981098
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Abstract
BACKGROUND CONTEXT: Surgical instrumentation used for posterior craniocervical instability has evolved from simple wiring techniques to sophisticated implant systems that incorporate multiple means of rigid fixation for the cervical spine. Polyaxial screws and lamina hooks in conjunction with occipital plating and transitional rods for caudal fixation theoretically allow for fixation points at each vertebra along the posterior aspect of the cervical spine. However, the potential for anatomical constraints to prevent intraoperative instrumentation at the desired vertebral level exists. The biomechanical implications of such "skipped segments" have not been well documented.
PURPOSE: The purpose of this study was to determine the bionnechanical effects of partial three-point fixation versus sequential fixation at all levels of the cervical spine from the occiput to T1.
STUDY DESIGN/SETTING: Fresh frozen human cadaveric cervical spines from the occiput (CO) to T1 were prepared and mounted on a spine simulator. Motion was assessed by a three-dimensional optoelectronic motion measurement system. Kinematic data were collected and range of motion (ROM) was analyzed and reported.
METHODS: Eight human noninstrumented intact spines (Treatment 1) were tested for baseline ROM which was subclassified into axial (CO-C2), upper subaxial (C2-C4), lower subaxial (C4-T1), and total (CO-T1) ROM. Flexion extension, lateral bending, and axial torsion testing with an applied +/- 3 Nm moment was conducted. The same testing protocol was performed after three-point fixation in which screws were placed at the CO, C4, and T1 (Treatment 2), and also after sequential fixation at all levels from CO through T1 (Treatment 3). Fixation was achieved using an occipital plate, 12-mm lateral mass screws for C3 through C6, and 20-min lateral mass or pedicle screws were used for C1, C2, C7, and T1.
RESULTS: Intact spine testing (Treatment 1) showed statistically significant larger ROM for all segments and for overall ROM when compared with both Treatment 2 (partial fixation CO, C4, and T1) and Treatment 3 (sequential fixation at all levels from the occiput to T1). When comparing Treatment 2 with Treatment 3, no significant difference in flexion extension ROM was detected between axial, upper subaxial, lower subaxial, and total overall ROM (p >.05). Lateral bending showed statistically significant increased ROM for Treatment 2 constructs compared with Treatment 3 constructs in total overall lateral bend ROM. For axial rotation, there was significantly increased ROM for Treatment 2 at the lower subaxial segment and total overall ROM (p <.05) when compared with Treatment 3.
CONCLUSIONS: There was no statistical difference between the three-point fixation treatment group and the sequential fixation group in flexion extension bending. Lateral bending and axial rotation demonstrated an increase in total overall ROM with partial fixation compared with fixation at all levels. Axial rotation in particular showed increased mobility in the lower cervical spine for the partial fixation group. In the instance where surgeons are not able to apply sequential fixation at diseased levels, especially for the lower subaxial cervical spine, particular attention to limitation of lateral bending and axial rotation by the use of external orthotics must be considered. (C) 2008 Elsevier Inc. All rights reserved.
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Details
- Title
- Biomechanical evaluation of occipitocervicothoracic fusion: impact of partial or sequential fixation
- Creators
- Boyle C. Cheng - UPMC PresbyterianMohamed A. Hafez - UPMC PresbyterianBryan Cunningham - UPMC PresbyterianHassan Serhan - UPMC PresbyterianWilliam C. Welch - UPMC Presbyterian
- Publication Details
- The spine journal, v 8(5), pp 821-826
- Publisher
- Elsevier
- Number of pages
- 6
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Surgery
- Web of Science ID
- WOS:000259535000017
- Scopus ID
- 2-s2.0-50049092921
- Other Identifier
- 991021930446504721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Clinical Neurology
- Orthopedics