Biomechanical Response under Stress-Controlled Tension-Tension Fatigue of a Novel Carbon Fiber/Epoxy Intramedullary Nail for Femur Fractures

Saeid Samiezadeh; Emil H Schemitsch; Radovan Zdero; Habiba Bougherara

doi:10.1016/j.medengphy.2020.04.001

Biomechanical Response under Stress-Controlled Tension-Tension Fatigue of a Novel Carbon Fiber/Epoxy Intramedullary Nail for Femur Fractures

Med Eng Phys. 2020 Jun:80:26-32. doi: 10.1016/j.medengphy.2020.04.001. Epub 2020 May 11.

Authors

Saeid Samiezadeh¹, Emil H Schemitsch², Radovan Zdero³, Habiba Bougherara⁴

Affiliations

¹ Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada, M5B2K3. Electronic address: saeid.samiezadeh@ryerson.ca.
² Division of Orthopaedic Surgery, Western University, London, ON, Canada N6A4V2. Electronic address: emil.schemitsch@lhsc.on.ca.
³ Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada, M5B2K3; Division of Orthopaedic Surgery, Western University, London, ON, Canada N6A4V2; Department of Mechanical and Materials Engineering, Western University, London, ON, Canada, N6A5B9. Electronic address: radovan.zdero@lhsc.on.ca.
⁴ Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada, M5B2K3. Electronic address: habiba.bougherara@ryerson.ca.

PMID: 32430231
DOI: 10.1016/j.medengphy.2020.04.001

Abstract

Metallic intramedullary nails are the "gold standard" implant for repairing femur shaft fractures. However, their rigidity may eliminate axial micromotion at the fracture (causing delayed healing) and they may carry too much load relative to the femur (causing "stress shielding"). Consequently, some researchers have proposed fiber-reinforced composite nails, but only one evaluated cyclic fatigue performance. Therefore, this study assessed the cyclic fatigue response of a carbon fiber/epoxy nail with a novel ply stacking sequence of [0₂/-45/45₂/-45/0/-45/45₂/-45₂/45₂/-45/90₂] previously developed by the present authors. Nails were cyclically loaded in tension-tension at 5 Hz with a stress ratio of R=0.1 from 30% - 85% of the material's ultimate tensile strength (UTS). Thermographic stress analysis, rather than conventional fatigue testing, was used to obtain high cycle fatigue strength (HCFS), below which the nail can be cyclically loaded indefinitely without damage. Also, the mechanical test machine's built-in load cell and an extensometer were used to create stress-strain curves, from which the change in static E^O and dynamic E* moduli were obtained. Results showed that HCFS was 70.3% of UTS (or about 283 MPa), while E^O and E* remained at 42 GPa without any dRegradation during testing. The current nail shows potential for clinical use.

Keywords: Biomechanics; Composite; Fatigue; Femur; Intramedullary nail.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomechanical Phenomena
Bone Nails
Carbon Fiber
Femoral Fractures*
Femur / surgery
Fracture Fixation, Intramedullary*
Humans
Stress, Mechanical

Substances

Carbon Fiber