Chapter 13 Fatigue Tests on Fiber Coated Titanium Implant–Bone Cement Interfaces M. Khandaker, Y. Li, P. Snow, S. Riahinezhad, and K. Foran Abstract The goal is developing an efficient bond interface between the implant and the cement by applying micron to nano size fibers to the surface of the implant through an electrospinning process, utilizing biocompatible fibers. Experimental models have been developed to evaluate the forces experienced on a cemented cylinder shape titanium implant through a static and cyclic tests. Finite element analysis (FEA) model for an uncoated cylindrical cemented titanium model was developed and tested under static and fatigue conditions. Our experimental study on cylindrical model found increase of pull out static strength for fiber coated implant (Mean strengthD1.308 MPa) compare to uncoated implant (Mean strengthD1.098 MPa) for 2 samples. Our experimental study also found no noticeable increase of pull out fatigue life for fiber coated implant (Mean fatigue lifeD2019 cycles) compare to uncoated implant (Mean fatigue lifeD2015 cycles) for 2 samples. Our FEA study on cylindrical model found the design life to be 1690 cycles with element size of 3.0E-3 m under the minimum stress of 112 kPa and maximum stress of 9.71 MPa according to Modified Goodman theorem. Keywords Titanium • Cement • Interface • PMMA • Polycaprolactone • Fatigue • Implant 13.1 Background The hip is an important multifunctional joint in the human musculoskeletal system. Since the hip is subject to position change, bending, and extreme force, much wear is imposed on the joint. For these reasons, along with age, health, and weight, a hip replacement is sometimes required and through a total hip replacement (THR) surgery. The most common practice in THR is the use of Titanium (Ti) implants secured in the patients’ femur using cement which causes further medical complications including particulates in the blood stream and primarily immobility. The goal of this project is to develop a more efficient bond interface between the implant and the cement by applying micro/nanofibers to the surface of the cylindrical and hip shape implants through an electrospinning process, analyzing results both experimentally and numerically. Various hip implants have different drawbacks and attributes. Many manufacturers have recalled their hip implants (including Johnson & Johnson, DePuy, and Zimmer Durom) [1]. A patient’s age, sex, weight, diagnosis, activity level, surgery condition and implant choice influence the longevity of the device. In the United States of America, five types of total hip replacement devices are currently used with different bearing surfaces [2] which are: metal-on-polyethylene, ceramic-on-polyethylene, metal-on-metal, ceramic-on-ceramic and ceramic-on-metal. The imperfection of the hip implant device can cause pain in the hip or leg, swelling at or near the hip joint, change in walking ability, and popping in the hip joint. A more suitable hip implant device which decreases the number of risks is needed [3]. The interfacial mechanics at the bone-cement or implant-cement interfaces is a critical issue for implant fixation and the filling of tissue defects created by disease [4]. Electro spinning is a process by which fibers with sub-micron diameters can be obtained from an electrostatically driven jet of polymer solution [5]. These fibers have a high surface area to volume ratio, which have numerous engineering applications [6–8]. The present study is based on the hypothesis that the differences of the surface properties at bone/cement interface due to incorporation of micro and sub-micron diameters fiber may have significant influence on the quality of bone/cement union. The objectives of this research were to: (1) develop aligned Poly("-caprolactone) PCL fiber coated cylindrical titanium implant, (2) conduct the fatigue tests on without and with fiber coated cylindrical titanium implant, and (3) develop a finite element model to determine the life of the without and with fiber coated cylindrical titanium implant. M. Khandaker ( ) • Y. Li • P. Snow • S. Riahinezhad • K. Foran Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA e-mail: mkhandaker@uco.edu © The Society for Experimental Mechanics, Inc. 2016 A.M. Beese et al. (eds.), Fracture, Fatigue, Failure and Damage Evolution, Volume 8, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-21611-9_13 95
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