Subsidence of Additively-Manufactured Cages in Foam Substrates: Effect of Contact Topology

Rachel R Collino; Ali Kiapour; Matthew R Begley

doi:10.1115/1.4046584

Subsidence of Additively-Manufactured Cages in Foam Substrates: Effect of Contact Topology

J Biomech Eng. 2020 Sep 1;142(9):091003. doi: 10.1115/1.4046584.

Authors

Rachel R Collino¹, Ali Kiapour², Matthew R Begley³

Affiliations

¹ Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545.
² Research & Development 4WEB Medical, Inc., Frisco, TX 75034.
³ Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106.

PMID: 32140715
DOI: 10.1115/1.4046584

Abstract

Subsidence of implants into bone is a major source of morbidity. The underlying mechanics of the phenomenon are not clear, but are likely related to interactions between contact stresses and the underlying porous trabecular bone structure. To gain insight into these interactions, we studied the penetration of three-dimensional (3D)-printed indenters with systematically varying geometries into Sawbones® foam substrates and isolated the effects of contact geometry from those of overall contact size and area. When size, contact area, and indented material stiffness and strength are controlled for, we show that resistance to penetration is in fact a function of topology only. Indenters with greater line contact lengths support higher subsidence loads in compression. These results have direct implications for the design of implants to resist subsidence into bone.

MeSH terms

Compressive Strength*
Materials Testing
Porosity
Prostheses and Implants
Spinal Fusion*
Weight-Bearing