Biomechanical implications of unilateral facetectomy, unilateral facetectomy plus partial contralateral facetectomy, and complete bilateral facetectomy in minimally invasive transforaminal interbody fusion

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Minimally invasive transforaminal interbody fusion techniques vary among surgeons. One decision point is whether to perform a unilateral facetectomy (UF), a unilateral facetectomy plus partial contralateral facetectomy (UF/PF), or a complete bilateral facetectomy (CBF). The authors therefore compared the biomechanical benefits of all 3 types of facetectomies to determine which approach produces improved biomechanical outcomes.


Seven human cadaveric specimens (L3–S1) were potted and prepped for UF, with full facet removal, hemilaminectomy, discectomy, and pedicle screw placement. After distraction, a fixed interbody spacer was placed, and compression was performed. A final fixation configuration was performed by locking the rods across the screws posteriorly with bilateral compression. Final lordosis angle and change and foraminal height were measured, and standard nondestructive flexibility tests were performed to assess intervertebral range of motion (ROM) and compressive stiffness. The same procedure was followed for UF/PF and CBF in all 7 specimens.


All 3 conditions demonstrated similar ROM and compressive stiffness. No statistically significant differences occurred with distraction, but CBF demonstrated significantly greater change than UF in mean foraminal height after bilateral posterior compression (1.90 ± 0.62 vs 1.00 ± 0.45 mm, respectively, p = 0.04). With compression, the CBF demonstrated significantly greater mean ROM than the UF (2.82° ± 0.83° vs 2.170° ± 1.10°, p = 0.007). The final lordosis angle was greatest with CBF (3.74° ± 0.70°) and lowest with UF (2.68° ± 1.28°). This finding was statistically significant across all 3 conditions (p ≤ 0.04).


Although UF/PF and CBF may require slightly more time and effort and incur more risk than UF, the potential improvement in sagittal balance may be worthwhile for select patients.

ABBREVIATIONS CBF = complete bilateral facetectomy; MIS = minimally invasive spine; PEEK = polyetheretherketone; PF = partial contralateral facetectomy; ROM = range of motion; TLIF = transforaminal lumbar interbody fusion; UF = unilateral facetectomy.

Article Information

Correspondence Laura A. Snyder: c/o Neuroscience Publications, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ.

INCLUDE WHEN CITING Published online May 10, 2019; DOI: 10.3171/2019.2.SPINE18942.

Disclosures Dr. Snyder is a consultant for Globus Medical and has received research funding from Medtronic.

© AANS, except where prohibited by US copyright law.



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    Illustration of the bone and joint removal of the 3 tested conditions, UF (A), UF/PF (B), and CBF (C). Copyright Barrow Neurological Institute, Phoenix, Arizona. Used with permission.

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    Bilateral screw distraction with a distractor tool at instrumented L4–5 of a potted cadaveric L3–S1 specimen.

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    Nonexpandable bullet-shaped PEEK interbody spacer that was placed in all specimens (A and B). The height of the interbody spacer was dependent on the specimen.

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    Bilateral rod lockdown with a compressor tool with compression at instrumented L4–5 in a potted cadaveric L3–S1 specimen.

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    Example of a potted cadaveric L3–S1 specimen instrumented at L4–5 with Optotrak 3020 sensors.

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    X-ray fluoroscopy of a potted cadaveric L3–S1 specimen under distraction at instrumented L4–5 (left) and after bilateral posterior lockdown of rods with compression at instrumented L4–5 (right).

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    Bilateral foraminal height change (mean ± SD) at L4–5 with pedicle screw-rod lockdown after bilateral compression in all 3 facetectomy conditions, UF, UF/PF, and CBF.

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    Change in lordosis angle (mean ± SD) at L4–5 from intact to pedicle screw-rod lockdown after bilateral compression in all 3 facetectomy conditions, UF, UF/PF, and CBF.


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