Finite element analysis of additive manufactured porous peek artificial vertebral bodies in lumbar total en bloc spondylectomy.

Abstract

Background: Lumbar total en bloc spondylectomy and internal fixation allows the removal of spinal tumors and the reconstruction of spinal stability. However, postoperative internal fixation failure due to unmatched spinal biomechanics remains obscure.

Purpose: This study aimed to assess the biomechanical characteristics of additive manufactured (AM) porous polyetheretherketone (PEEK) artificial vertebral body for total en bloc spondylectomy and internal fixation.

Study design/setting: Comparative finite element (FE) study.

Methods: We created porous artificial vertebral bodies using medical-grade PEEK filaments and fused deposition modeling (FDM) technology, and evaluated the mechanical properties of the solid and porous implants. A finite element model of intact L1-L5 was created to analyze biomechanical characteristics of 5 operative constructs for reconstructing the lumbar anterior column. The lumbar anterior column was reconstructed using a titanium alloy mesh and bone graft (Ti+B) and AM PEEK artificial vertebral bodies with solid or porous structures. The maximum von Mises stresses of implants and adjacent structures were analyzed and compared under physiological conditions.

Results: AM PEEK artificial vertebral bodies reduced von Mises stress on the artificial vertebral body, adjacent vertebral bodies, and intervertebral discs. The AM porous PEEK artificial vertebral body (PEEK-500) exhibited the lowest von Mises stress of the artificial vertebral body, adjacent vertebral bodies, and intervertebral discs.

Conclusions: Ti+B increased the maximum stress on adjacent vertebral bodies, suggesting that it has the potential for mesh subsidence. Moreover, PEEK-500 had minimal impact on the internal implants and adjacent structures. This indicated that the lumbar anterior column reconstructed with AM porous PEEK artificial vertebral bodies may decrease the risk of postoperative internal fixation failure and adjacent segment degeneration.

Clinical significance: Manufactured porous PEEK artificial vertebral bodies demonstrated a minimal impact on both the internal implants and adjacent structures. This suggests that reconstructing the lumbar anterior column with AM porous PEEK artificial vertebral bodies can decrease the risk of postoperative internal fixation failure and adjacent segments degeneration.