Biomechanical Comparison of Anterior Lumbar Screw-plate Fixation versus Posterior Lumbar Pedicle Screw Fixation

Anterior lumbar interbody fusion （ALiF） followed by posterior pedicle screw fixation （PSF） in a second procedure is mostly used to implement lumbar spine fusion. ALIF followed by an- terior lumbar screw-plate has a lot of advantages, but its biomechanical stability requires confirma- tion. This study evaluated the biomechanical stability of a novel anterior lumbar locked screw-plate （ALLSP） by comparison with posterior lumbar PSF. Twelve fresh human cadaveric lumbar speci- mens （L4-L5） were assigned to four groups： ALIF~PSF group, ALIF＋ALLSP （both fixed） group, ALIF group and an untreated control （both non-fixed） group. The first three groups received implan- tation of a rectangular titanium cage. Tests under axial compression, flexion, extension, lateral bend- ing, or rotation showed that the fixed groups had significantly stronger stability than the non-fixed groups （P=-0.000 for all）. The ALIF＋ALLSP group had significantly greater axial stiffness under ap- plied axial compression and significantly less angular displacement under rotational forces than the ALIF＋PSF group. The angular displacement of the ALIF＋ALLSP group was less under flexion than that of the ALIF＋PSF, and the angular displacement under lateral bending and extension was greater, but these differences were not statistically significant. In summary, the ALLSP conforms to the ante- rior lumbar spine and has good biomechanical stability. It is a reliable choice for enhancing the sta- bility of ALIF.