In vitro biomechanical comparison of an anterior and anterolateral lumbar plate with posterior fixation following single-level anterior lumbar interbody fusion.

OBJECT: Anterior lumbar interbody fusion (ALIF) is often supplemented with instrumentation to increase stability in the spine. If anterior plate fixation provided the same stability as posterior pedicle screw fixation (PSF), then a second approach and its associated morbidity could be avoided.
METHODS: Seven human cadaveric L4-5 spinal segments were tested under three conditions: ALIF with an anterior plate, ALIF with an anterolateral plate, and ALIF supplemented by PSF. Range of motion (ROM) was calculated for flexion/extension, lateral bending, and axial torsion and compared among the three configurations.
RESULTS: There were no significant differences in ROM during flexion/extension, lateral bending, or axial torsion among any of the three instrumentation configurations.
CONCLUSIONS: The addition of an anterior plate or posterior PS/rod instrumentation following ALIF provides substantially equivalent biomechanical stability. Additionally, the position of the plate system, either anterior or anterolateral, does not significantly affect the stability gained.