Influence of sequential opening/closing of interface gaps and texture density on bone growth over macro-textured implant surfaces using FE based mechanoregulatory algorithm

Abstract

Intramedullary implant fixation is achieved through a press-fit between the implant and the host bone. A stronger press-fit between the bone and the prosthesis often introduces damage to the bone canal creating micro-gaps. The aim of the present investigation is to study the influences of simultaneous opening/closing of gaps on bone growth over macro-textured implant surfaces. Models based on textures available on CORAIL and SP-CL hip stems have been considered and 3D finite element (FE) analysis has been carried out in conjunction with mechanoregulation based tissue differentiation algorithm. Additionally, using a full-factorial approach, different combinations (between 5 µm to 15 µm) of sliding and gap distances at the bone-implant interface were considered to understand their combined influences on bone growth. All designs show an elevated fibrous tissue formation (10.96% at 5 µm to 29.38% at 40 µm for CORAIL based textured model; 11.45% at 5 µm to 32.25% at 40 µm for SP-CL based textured model) and inhibition of soft cartilaginous tissue (75.64% at 5 µm to 53.94% at 40 µm for CORAIL based model; 76.02% at 5 µm to 53.60% at 40 µm SP-CL based model) at progressively higher levels of normal micromotion, leading to a fragile bone-implant interface. These results highlight the importance of minimizing both sliding and gap distances simultaneously to enhance bone growth and implant stability. Further, results from the studies with differential texture density over CORAIL based implant reveal a non-linear complex relationship between tissue growth and texture density which might be investigated in a machine learning framework.

Keywords:

• Uncemented implant
• bone growth
• opening/closing gap
• mechanoregulation
• texture density
• finite element analysis

Acknowledgements

The authors would like to acknowledge the computational facilities available at the Composite Structures and Fracture Mechanics Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Guwahati, India, which has helped to carry out the research study. The study was partially funded by SPARC, MHRD, Government of India (Project ID: SPARC/P705).

Disclosure statement

There are no possible conflicts of interest for the authors in terms of funding support, research, authorship, or publishing of this article.

Funding

This work was supported by SPARC, MHRD, Government of India (Project ID: SPARC/P705).