Development of fatigue lifetime predictive test methods for hip implants: Part I. Test methodology

Styles, C. M.; Evans, Samuel Lewin; Gregson, P.J.

doi:10.1016/s0142-9612(98)00031-3

Cited by 25 publications

(6 citation statements)

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“…This is below the fatigue data for this material of around 470 MPa (high-nitrogen stainless steel (Orthinox ® ), at 10 7 cycles, 10 Hz, in Eagle’s medium at 37°C) reported in the literature, 25 but with the same stress ratio of R = 0.1 which is typical for implant loadings. 22 , 27 It is important to note that this value depends on various parameters, for example, manufacturing, heat treatment, surface finish, size, and so on and can, therefore, yield only approximate evaluations. Thus, the remaining margin of around 50 MPa between the simulated maximum stress at the cavity base and the fatigue value from literature is small also with respect to FE model deviations from the quasi-static testing.…”

Section: Discussionmentioning

confidence: 99%

Endurance testing and finite element simulation of a modified hip stem for integration of an energy harvesting system

Lange

Bader

Kluess

2021

Proc Inst Mech Eng H

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Instrumented implants are a promising approach to further improve the clinical outcome of total hip arthroplasties. For the integrated sensors or active functions, an electrical power supply is required. Energy harvesting concepts can provide autonomous power with unlimited lifetime and are independent from external equipment. However, those systems occupy space within the mechanically loaded total hip replacement and can decrease the life span due to fatigue failure in the altered implant. We previously presented a piezoelectric energy harvesting system for an energy-autonomous instrumented total hip stem that notably changes the original implant geometry. The aim of this study was to investigate the remaining structural fatigue failure strength of the metallic femoral implant component in a worst-case scenario. Therefore, the modified hip stem was tested under load conditions based on ISO 7206-4:2010. The required five million cycles were completed twice by all samples (n = 3). Additionally applied cycles with incrementally increased load levels up to 4.7 kN did not induce implant failure. In total, 18 million cycles were endured, outperforming the requirements of the ISO standard. Supplementary finite element analysis was conducted to determine stress distribution within the implant. A high stress concentration was found in the region of modification. The stress level showed an increase compared to the previously evaluated physiological loading situation and was close to the fatigue data from the literature. The stress concentration factor compared to the original geometry amounted to 2.56. The assessed stress level in accordance with the experimental fatigue testing can serve as a maximum reference value for further implant design modifications and optimisations.

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Section: Discussionmentioning

confidence: 99%

Endurance testing and finite element simulation of a modified hip stem for integration of an energy harvesting system

Lange

Bader

Kluess

2021

Proc Inst Mech Eng H

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“…Such spectra [ 31 , 32 ] can be used as benchmarks to validate the design of the component. In the field of prosthetic implants, this approach has not been widely applied, even if one can find an interesting example for the hip joint [ 33 ]. Here, a typical sequence of walking and stair-climbing was recorded as a representative daily routine and repeatedly applied until failure.…”

Section: Random Spectrum Loading Of Dental Implantsmentioning

confidence: 99%

Fatigue of Dental Implants: Facts and Fallacies

Shemtov‐Yona

Rittel

2016

Dentistry Journal

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Dental implants experience rare yet problematic mechanical failures such as fracture that are caused, most often, by (time-dependent) metal fatigue. This paper surveys basic evidence about fatigue failure, its identification and the implant’s fatigue performance during service. We first discuss the concept of dental implant fatigue, starting with a review of basic concepts related to this failure mechanism. The identification of fatigue failures using scanning electron microscopy follows, to show that this stage is fairly well defined. We reiterate that fatigue failure is related to the implant design and its surface condition, together with the widely varying service conditions. The latter are shown to vary to an extent that precludes devising average or representative conditions. The statistical nature of the fatigue test results is emphasized throughout the survey to illustrate the complexity in evaluating the fatigue behavior of dental implants from a design perspective. Today’s fatigue testing of dental implants is limited to ISO 14801 standard requirements, which ensures certification but does not provide any insight for design purposes due to its limited requirements. We introduce and discuss the random spectrum loading procedure as an alternative to evaluate the implant’s performance under more realistic conditions. The concept is illustrated by random fatigue testing in 0.9% saline solution.

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“…HIPing has been shown to increase fatigue lifetime [275], but there is evidence that it has negligible effect on fatigue strength when variable amplitude loading is considered 276]. This is crucial to orthopaedic settings, as variable loading is typical during walking and is observed in orthopaedic models [277]. There are fewer studies of CoCr based alloys, though similar improvements in fatigue strength from the as built state Fig.…”

Section: Thermal Post Processing For Fatiguementioning

confidence: 99%

Clinical, industrial, and research perspectives on powder bed fusion additively manufactured metal implants

Lowther

Louth

Davey

et al. 2019

Additive Manufacturing

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A B S T R A C TFor over ten years, metallic skeletal endoprostheses have been produced in select cases by additive manufacturing (AM) and increasing awareness is driving demand for wider access to the technology. This review brings together key stakeholder perspectives on the translation of AM research; clinical application, ongoing research in the field of powder bed fusion, and the current regulatory framework. The current clinical use of AM is assessed, both on a mass-manufactured scale and bespoke application for patient specific implants. To illuminate the benefits to clinicians, a case study on the provision of custom cranioplasty is provided based on prosthetist testimony. Current progress in research is discussed, with immediate gains to be made through increased design freedom described at both meso-and macro-scale, as well as long-term goals in alloy development including bioactive materials. In all cases, focus is given to specific clinical challenges such as stress shielding and osseointegration. Outstanding challenges in industrialisation of AM are openly raised, with possible solutions assessed. Finally, overarching context is given with a review of the regulatory framework involved in translating AM implants, with particular emphasis placed on customisation within an orthopaedic remit. A viable future for AM of metal implants is presented, and it is suggested that continuing collaboration between all stakeholders will enable acceleration of the translation process. fection or surgical complications [11][12][13].Currently, the majority of skeletal endoprostheses are produced from titanium (Ti) or cobalt chromium (CoCr) based alloys, which meet the criteria of durability, strength, corrosion resistance and a low immune response [14,15]. These characteristics however come at the cost of the high stiffness of these alloys in comparison to bone. Mismatch between the mechanical properties of bone and orthopaedic materials

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Development of fatigue lifetime predictive test methods for hip implants: Part I. Test methodology

Cited by 25 publications

References 0 publications

Endurance testing and finite element simulation of a modified hip stem for integration of an energy harvesting system

Endurance testing and finite element simulation of a modified hip stem for integration of an energy harvesting system

Fatigue of Dental Implants: Facts and Fallacies

Clinical, industrial, and research perspectives on powder bed fusion additively manufactured metal implants

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