Assessing the performance characteristics and clinical forces in simulated shape memory bone staple surgical procedure: The significance of SMA material model. (1st July 2015)

• Record Type: Journal Article
• Authors: Saleeb, A.F.; Dhakal, B.; Owusu-Danquah, J.S.
• Is Part Of: Computers in biology and medicine. Volume 62(2015)
• Page Start: 185
• Page End: 195
• Publication Date: 2015-07-01
• Subjects: NiTi -- Bone-staple -- Simulation -- SMA material model -- Clamping force; Medicine -- Data processing -- Periodicals; Biology -- Data processing -- Periodicals; 610.285
• DOI: 10.1016/j.compbiomed.2015.04.010
• Languages: English
• ISSNs: 0010-4825

Abstract

Abstract: This work is focused on the detailed computer simulation of the key stages involved in a shape memory alloy (SMA) osteosynthesis bone stapling procedure. To this end, a recently developed three-dimensional constitutive SMA material model was characterized from test data of three simple uniaxial-isothermal-tension experiments for powder metallurgically processed nickel-rich NiTi (PM/NiTi-P) material. The calibrated model was subsequently used under the complex, thermomechanical loading conditions involved in the surgical procedure using the body-temperature-activated PM/NiTi-P bone staple. Our aim here is to assess the immediate and post-surgical performance characteristics of the stapling operation using the material model. From this study: (1) it was found that adequate compressive forces were developed by the PM/NiTi-P bone staple, with the tendency of this force to even increase under sustained thermal loading due to the intrinsic "inverse relaxation phenomena" in the SMA material, (2) the simulation results correlated well with those from experimental measurements, (3) the body-temperature-activated PM/NiTi-P staple was proved to be clinically viable, providing a stable clamping force needed for speedy coaptation of the fractured bones, and (4) these realistic assessments crucially depend on the use of suitable and comprehensive SMA material models. Highlights: A powder metallurgically processed NiTi material was calibrated for the bone staple. Pre/post-surgical performance is studied for a body-temperature-activated SMA staple. Generated staple forces tended to increase under sustained thermal loading. The simulation results correlated well with the experimental measurements. The thermal activation scheme of the SMA staple was proved to be clinically viable.