Biomechanical Evaluation of a Novel Autogenous Bone Interbody Fusion Cage for Posterior Lumbar Interbody Fusion in a Cadaveric Model

Abstract

A human cadaveric biomechanical study of a novel, prefabricated autogenous bone interbody fusion (ABIF) cage. To evaluate the biomechanical properties of the ABIF cage in a single-level construct with and without transpedicular screw and rod fixation. In current practice, posterior lumbar interbody fusion is generally carried out using synthetic interbody spacers or corticocancellous iliac crest bone graft (ICBG) in combination with posterior instrumentation. However, questions remain concerning the use of synthetic intervertebral implants as well as the morbidity ICBG harvesting. Therefore, ABIF cage has been developed to obviate some of the challenges in conventional posterior lumbar interbody fusion instrumentation and to facilitate the fusion process. Eighteen adult cadaveric lumbosacral (L3-S1) specimens were tested. Test conditions included single lumbosacral segments across (1) intact, (2) decompressed, (3) intervertebral cage alone, and (4) intervertebral cage with bilateral transpedicular fixation. Range of motion (ROM), neutral zone (NZ), and axial failure load were tested for each condition. The ICBG, polyetheretherketone cage, or ABIF cage alone exhibited a significantly lower (P < 0.05) ROM and NZ than the decompressed spine. In comparison with the intact spine, all 3 test conditions without supplemental fixation were able to decrease ROM and NZ to near intact levels. When stabilized with pedicle screws, the ROM was significantly less and the NZ was significantly lower (P < 0.05) for each group both compared with the intact spine. In axial compression testing, the failure load of polyetheretherketone cage was the highest, with no significant difference between the ICBG and the ABIF cage. These data suggest that the novel ABIF cage can bear the physiological intervertebral peak load, similar to ICBG. When combined with pedicle screw and rod fixation, it exhibits similar biomechanical properties as the polyetheretherketone cage plus posterior instrumentation. Based on the biomechanical properties of ABIF cage, the prospect of these cages in clinical practice is expected.