Novel Modular Spine Blocks Affect the Lumbar Spine on Finite Element Analysis

Area of Science:

• Spine biomechanics
• Orthopedic surgery
• Biomaterials

Background:

• Osteoporotic vertebral compression fractures (OVCFs) pose significant clinical challenges.
• Current surgical interventions aim to restore stability and alleviate pain.
• Modular spine blocks (MSB) represent a novel, assembled intravertebral fixator for OVCF management.

Purpose of the Study:

• To quantitatively assess force distribution in vertebrae using finite element analysis (FEA).
• To investigate the biomechanical effects of different MSB structural designs and implantation methods.
• To evaluate the impact of MSB on adjacent spinal segments.

Main Methods:

• A three-dimensional nonlinear FEA model of an L3 vertebra implanted with MSB was constructed.
• Simulations analyzed solid vs. hollow MSB designs and three-layered vs. six-layered, unilateral vs. bilateral implantation.
• The model underwent preload and simulated flexion, extension, torsion, and lateral bending to assess intervertebral range of motion (ROM), disk stress, and intravertebral force distribution.

Main Results:

• MSB configurations demonstrated comparable stability, with minimal impact on adjacent segment ROM and disk stress.
• Solid MSB designs facilitated even force distribution within the vertebrae.
• Unilateral, three-layered hollow MSB exhibited lower maximum stress values compared to bilateral, six-layered solid MSB.

Conclusions:

• MSB exhibits minimal stress shielding on intervertebral ROM and does not induce additional loading on adjacent disks.
• Surgeons can select appropriate MSB configurations for vertebral fixation with reduced concerns regarding complications.
• The study supports MSB as a viable option for managing OVCFs, offering flexibility and potentially mitigating risks like implant failure or adjacent segment disease.