Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 2: Treatment with threaded interbody cages/dowels and pedicle screws

Document Type

Article

Abstract

Object. The authors sought to determine the biomechanical effectiveness of threaded interbody cages or dowels compared with that achieved using pedicle screw instrumentation in resisting Grade I lumbar spine degenerative spondylolisthesis. Methods. Thirty-three levels obtained from seven cadaveric lumbar spines were instrumented with cages or dowels, pedicle screw/rod instrumentation, or both. Entire specimens were loaded with nonconstraining torques. Each level was loaded with anteroposterior shear forces while an optical system was used to measure the specimen's motion at individual levels. Pedicle screw/rods outperformed interbody cages and dowels in treating spondylolisthesis. Cages or dowels alone provided only moderate biomechanical stability, and their effectiveness depended heavily on the integrity of the ligaments and remaining annulus, whereas the success of pedicle screw fixation relied predominantly on the integrity of the bone for solid fixation. Little biomechanical difference was demonstrated between cages and dowels; both devices were susceptible to loosening with cyclic fatigue. Conclusions. Biomechanically, cages or dowels alone were suboptimal for treating lumbar spondylolisthesis, especially compared with pedicle screw/rods. Threaded cages or dowels used together with pedicle screws/rods created the most stable construct.

Keywords

Anterior lumbar interbody fusion, Biomechanics, Degenerative spondylolisthesis, Threaded interbody cages

Publication Date

1-1-2001

Publication Title

Journal of Neurosurgery

ISSN

00223085

Volume

94

Issue

1 SUPPL.

First Page

51

Last Page

60

PubMed ID

11147868

Digital Object Identifier (DOI)

10.3171/spi.2001.94.1.0051

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