Simulation and validation of spinal construct testing based on ASTM F1717

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Spinal fixation constructs require rigorous mechanical evaluation before clinical application.
• ASTM F1717 provides a standardized vertebrectomy model for static mechanical testing.
• Finite element analysis (FEA) is increasingly used to simulate and predict mechanical behavior.

Purpose of the Study:

• To assess the mechanical performance of spinal fixation constructs using ASTM F1717.
• To validate the use of FEA in simulating construct mechanics for design decisions.
• To identify key geometric factors influencing construct mechanical response.

Main Methods:

• Constructs with Ti-6Al-4V ELI pedicle screws and UHMWPE blocks were tested per ASTM F1717.
• Four screw configurations varying diameter and length were evaluated under static compression and tension.
• FEA models (jig included and excluded) were compared against experimental data.

Main Results:

• FEA showed strong agreement with experimental results (errors typically <5%).
• Increasing screw diameter significantly increased reaction forces compared to screw length.
• Jig excluded models reduced computational time by 20-32% with minimal impact on accuracy.

Conclusions:

• Validated FEA accurately reproduces ASTM F1717 construct behavior, serving as a valuable tool for early design screening.
• Screw diameter is the dominant geometric factor influencing construct mechanics, with length having a lesser effect.
• FEA can reliably complement physical testing in spinal implant design, potentially enhancing structural durability and surgical safety.