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Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine.
Spine (Phila Pa 1976). 2003 Oct 15; 28(20):2352-8; discussion 2358.S

Abstract

STUDY DESIGN

An in vitro biomechanical study of several reconstructive techniques after a two-level cervical corpectomy.

OBJECTIVES

To evaluate, compare, and quantitate the stability of several reconstructive strategies (anterior, posterior, or anterior/posterior with or without instrumentation) after a multilevel cervical corpectomy.

SUMMARY OF BACKGROUND DATA

Several clinical and biomechanical studies have questioned the stability of stand-alone long-segment anterior plate fixation after a multilevel (>or=2) corpectomy. The large cantilever forces generated within the stabilized construct, particularly at the caudal screw-bone interface, have led to plate and screw dislodgement and the need for further surgical intervention. The addition of posterior segmental instrumentation has been shown to improve overall stability and decrease local stresses on the anterior fusion construct (graft and plate).

MATERIALS AND METHODS

Seven fresh-frozen cadaveric human cervical spines (C1-T1) were harvested. The C1-C2 and C7-T1 vertebral bodies were embedded in poly-methylmethacrylate (PMMA). Three VICON cameras tracked three-dimensional segmental motions at the ends of the fusion construct after a two-level corpectomy and placement of a strut graft with or without instrumentation. Pure moments (flexion/extension, lateral bending, and axial rotation) were applied to the C1 level of each specimen. The motion segments were loaded to a maximum of 2 Nm using dead weights. Testing was first performed on the intact specimens. Then, a two-level corpectomy at the C4 and C5 levels was performed. A PMMA strut graft was then placed into the corpectomy site. Biomechanical testing was then repeated among three different reconstruction techniques: 1) anterior cervical locking plate (PEAK; Depuy-Acromed, Raynham, MA) with dual unicortical screw fixation at C3 and C6; 2) posterior cervical instrumentation (Summit; Depuy-Acromed) using a 3.0-mm rod with segmental lateral mass screw fixation from C3 to C6; and 3) a combined anterior-posterior instrumentation using the anterior PEAK plate and posterior Summit rod system.

RESULTS

In all pure moments tested (flexion/extension/lateral bending/axial rotation) the combined anterior-posterior instrumentation reconstruction model and the posterior-only instrumentation model were significantly more rigid than the anterior-only instrumentation model (P < 0.05). Interestingly, no statistically significant difference was noted between the combined anterior plate/posterior instrumentation model and the posterior instrumentation-only model.

CONCLUSION

The biomechanical results obtained suggest that posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy regardless of the presence or absence of anterior instrumentation. In cases in which the stability of a multilevel reconstruction procedure is tenuous, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct.

Authors+Show Affiliations

Department of Orthopaedic Surgery, Rush-Presbyterian St. Luke's Medical Center, Chicago, IL 60612, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

14560082

Citation

Singh, Kern, et al. "Biomechanical Comparison of Cervical Spine Reconstructive Techniques After a Multilevel Corpectomy of the Cervical Spine." Spine, vol. 28, no. 20, 2003, pp. 2352-8; discussion 2358.
Singh K, Vaccaro AR, Kim J, et al. Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine. Spine. 2003;28(20):2352-8; discussion 2358.
Singh, K., Vaccaro, A. R., Kim, J., Lorenz, E. P., Lim, T. H., & An, H. S. (2003). Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine. Spine, 28(20), 2352-8; discussion 2358.
Singh K, et al. Biomechanical Comparison of Cervical Spine Reconstructive Techniques After a Multilevel Corpectomy of the Cervical Spine. Spine. 2003 Oct 15;28(20):2352-8; discussion 2358. PubMed PMID: 14560082.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine. AU - Singh,Kern, AU - Vaccaro,Alexander R, AU - Kim,Jesse, AU - Lorenz,Eric P, AU - Lim,Tae-Hong, AU - An,Howard S, PY - 2003/10/16/pubmed PY - 2005/6/14/medline PY - 2003/10/16/entrez SP - 2352-8; discussion 2358 JF - Spine JO - Spine VL - 28 IS - 20 N2 - STUDY DESIGN: An in vitro biomechanical study of several reconstructive techniques after a two-level cervical corpectomy. OBJECTIVES: To evaluate, compare, and quantitate the stability of several reconstructive strategies (anterior, posterior, or anterior/posterior with or without instrumentation) after a multilevel cervical corpectomy. SUMMARY OF BACKGROUND DATA: Several clinical and biomechanical studies have questioned the stability of stand-alone long-segment anterior plate fixation after a multilevel (>or=2) corpectomy. The large cantilever forces generated within the stabilized construct, particularly at the caudal screw-bone interface, have led to plate and screw dislodgement and the need for further surgical intervention. The addition of posterior segmental instrumentation has been shown to improve overall stability and decrease local stresses on the anterior fusion construct (graft and plate). MATERIALS AND METHODS: Seven fresh-frozen cadaveric human cervical spines (C1-T1) were harvested. The C1-C2 and C7-T1 vertebral bodies were embedded in poly-methylmethacrylate (PMMA). Three VICON cameras tracked three-dimensional segmental motions at the ends of the fusion construct after a two-level corpectomy and placement of a strut graft with or without instrumentation. Pure moments (flexion/extension, lateral bending, and axial rotation) were applied to the C1 level of each specimen. The motion segments were loaded to a maximum of 2 Nm using dead weights. Testing was first performed on the intact specimens. Then, a two-level corpectomy at the C4 and C5 levels was performed. A PMMA strut graft was then placed into the corpectomy site. Biomechanical testing was then repeated among three different reconstruction techniques: 1) anterior cervical locking plate (PEAK; Depuy-Acromed, Raynham, MA) with dual unicortical screw fixation at C3 and C6; 2) posterior cervical instrumentation (Summit; Depuy-Acromed) using a 3.0-mm rod with segmental lateral mass screw fixation from C3 to C6; and 3) a combined anterior-posterior instrumentation using the anterior PEAK plate and posterior Summit rod system. RESULTS: In all pure moments tested (flexion/extension/lateral bending/axial rotation) the combined anterior-posterior instrumentation reconstruction model and the posterior-only instrumentation model were significantly more rigid than the anterior-only instrumentation model (P < 0.05). Interestingly, no statistically significant difference was noted between the combined anterior plate/posterior instrumentation model and the posterior instrumentation-only model. CONCLUSION: The biomechanical results obtained suggest that posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy regardless of the presence or absence of anterior instrumentation. In cases in which the stability of a multilevel reconstruction procedure is tenuous, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct. SN - 1528-1159 UR - https://www.unboundmedicine.com/medline/citation/14560082/Biomechanical_comparison_of_cervical_spine_reconstructive_techniques_after_a_multilevel_corpectomy_of_the_cervical_spine_ L2 - http://dx.doi.org/10.1097/01.BRS.0000085344.22471.23 DB - PRIME DP - Unbound Medicine ER -