428 - Biomechanical Assessment of Demineralized Bone Matrix with or without...

#428 Biomechanical Assessment of Demineralized Bone Matrix with or without Extraforaminal Lumbar Interbody Fixation

Lumbar Therapies and Outcomes

Poster Presented by: N. Rodriguez-Martinez

Author(s):

N.G. Rodriguez-Martinez (1)
K.R. Chin (2)
P.M. Reyes (1)
A.G.U.S. Newcomb (1)
S. Kalb (1)
N.R. Crawford (1)

(1) Barrow Neurological Institute, Spinal Biomechanics Laboratory, Phoenix, AZ, USA
(2) SpineFrontier Inc., Beverly, MA, USA

Abstract

Introduction: Particulate demineralized bone matrix (DBM) may be useful in lumbar spine fusion. Although the biological efficacy of DBM has been shown, little research has studied the biomechanics of particulate fillers. The purpose of this study is to assess whether DBM can provide biomechanical support when used as stand-alone disc space filler or for augmenting a polyetheretherketone cage during extraforaminal lumbar interbody fusion (ELIFT).

Material and Methods: Seven human cadaveric lumbar spine segments from L3-S1 underwent biomechanical angular flexibility testing followed by axial compression flexibility testing in nine conditions as follows: 1. Native disc, 2. Discectomy, 3. ELIFT alone (no DBM), 4. ELIFT + DBM (remainder disc space filled), 5. DBM alone (no ELIFT) 25% of disc space, 6. DBM 50% of disc space, 7. DBM 75% of disc space, 8. DBM 100% of disc space, 9. DBM 100% of disc space after 10,000 cycles of loading. Specimens were loaded using pure moments (7.5 Nm) to induce flexion, extension, lateral bending, and axial rotation or using axial compressive force (300 N) while motion was recorded optoelectronically.

Results: After discectomy, the use of DBM alone did not reduce the angular ROM in any of the loading conditions (p>0.9, RM-ANOVA, Fig 1). Compared to discectomy, the use of the ELIFT alone decreased the ROM in extension and lateral bending (p< 0.04), but not in flexion or axial rotation (p>0.24). With ELIFT + DBM, the ROM was no different than ELIFT alone (p>0.9). The axial compressive ROM was not significantly different with ELIFT, ELIFT+DBM, or DBM alone (p>0.10, Fig. 2). The interpedicular distance slightly but statistically insignificantly increased with progressively more DBM in the disc space (p>0.76). After cyclic loading there was no change in angular or compressive flexibility or interpedicular distance (p>0.14).

Conclusion: Packing the disc space with DBM particles alone does not provide noticeable stability or increased foraminal height over leaving the disc space empty due to the challenging mechanical environment of the lumbar disc space. Similarly, ELIFT+DBM does not provide improved stability over ELIFT alone. ELIFT was more effective in restoring stability during extension and lateral bending than during flexion or axial rotation.

Fig. 1. Mean normalized angular ROM

Fig. 2. Mean normalized interpedicular distance