# Influence of the Cortical Layer Thickness and Trabecular Layer Pattern Density on 3D-Printed Femur Strength

## TL;DR

This study explores how varying the thickness of a 3D-printed femur's outer layer and the density of its inner layer affects the bone's compressive strength.

## Contribution

The novelty lies in systematically analyzing how cortical layer thickness and trabecular pattern density influence the mechanical strength of 3D-printed femurs.

## Key findings

- A 3D-printed femur with 3.0 mm outer layer thickness and 30% infill showed the highest compressive strength of 4778 N.
- The lowest compressive strength was observed in a femur with 1.2 mm outer thickness and 20% infill, at 2116 N.
- Failure patterns predominantly involved fractures at the proximal end of the femur.

## Abstract

This paper presents the process of preparing and conducting a uniaxial compression test, developing the results, and determining the compressive strength of a femur made using 3D printing technology. The study considers the variable thickness of the outer layer—imitating cortical bone tissue—and the varying density of the inner layer—imitating trabecular bone tissue—which, with further analysis, may aim to replicate different states of osteoporosis. The compressive strength of the bones varied depending on the thickness of the outer layer and the filling degree. Failure patterns were observed, corresponding to different variants of the produced bones. The predominant failure pattern was the fracture of the femoral head or neck at the proximal end of the femur. The results were compared with previous studies on commercial femur bones, as well as those created using 3D printing technology by other authors. The highest compressive strength was found in the bone with an outer layer thickness of 3.0 mm and 30% infill, with a value of 4778 N. A very similar compressive strength was recorded for the bone with an outer thickness of 2.1 mm and 30% infill, reaching 4519 N. The lowest compressive strength, 2116 N, was observed in the bone with an outer thickness of 1.2 mm and 20% infill.