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Biomechanical Comparison of Posterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion Performed at 1 and 2 Levels

Ames, Christopher P. MD*; Acosta, Frank L. Jr MD*; Chi, John MD, MPH*; Iyengar, Jaicharan BS†; Muiru, William BS‡; Acaroglu, Emre MD§; Puttlitz, Christian M. PhD§

Biomechanics

Study Design. Biomechanical laboratory study of human cadaveric spines.

Objective. To determine the difference in acute stability between posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) performed at 1 and 2 levels with and without posterior fixation.

Summary of Background Data. Circumferential spinal fusion with both an interbody graft and posterior pedicle screw-rod construct has been advocated to decrease pseudarthrosis rates. Both PLIF and TLIF theoretically allow for 3-column fixation and fusion.

Methods. Specimens underwent either PLIF or TLIF at L2–L3 (single-level) and L3–L4 (2-level), both with and without pedicle screw instrumentation. During TLIF, an interbody allograft was placed in the anterior or middle column. Nondestructive, nonconstraining pure moment loading was applied to each specimen.

Results. There were no significant differences in the range of motion after either PLIF or TLIF at 1 level. The addition of pedicle screws tended more strongly to increase rigidity after 1-level PLIF compared to TLIF. Position of the TLIF graft did not affect stability. The addition of pedicle screws to a 2-level construct significantly reduced all motions tested.

Conclusions. Based on our findings, posterior fixation with a pedicle screw-rod construct is suggested for 1-level PLIF and TLIF, and is necessary to achieve stability after interbody fusion across 2 levels using either technique.

Cadaveric lumbar spines underwent either posterior lumbar interbody fusion or transforaminal lumbar interbody fusion at 1 or 2 levels. Neither approach imparted a significant degree of stability without supplemental pedicle screw fixation. Posterior fixation with a pedicle screw-rod construct is suggested for 1-level posterior lumbar interbody fusion and transforaminal lumbar interbody fusion, and is necessary to achieve stability after fusion across 2 levels.

From the *Department of Neurological Surgery, †School of Medicine, ‡Department of Biomedical Engineering, and §Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA.

Acknowledgment date: January 31, 2005. First revision date: April 7, 2005. Acceptance date: April 8, 2005.

The device(s)/drug(s) that is/are the subject of this manuscript is/are not FDA-approved fro this indication and is/are not commercially available in the United States.

Corporate/Industry 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.

Address correspondence and reprint requests to Christopher P. Ames, MD, Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, M-779, San Francisco, CA 94143-0112; E-mail: amesc@neurosurg.ucsf.edu

© 2005 Lippincott Williams & Wilkins, Inc.