Influence of geometry and materials on the axial and torsional strength of the head–neck taper junction in modular hip replacements: A finite element study

Fallahnezhad, Khosro; Farhoudi, Hamidreza; Oskouei, Reza Hashemi; Taylor, Mark

doi:10.1016/j.jmbbm.2015.12.044

Cited by 36 publications

(45 citation statements)

References 25 publications

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“…CoCr possesses a higher (almost double) modulus when compared with Ti6Al4V, meaning that the contact area between trunnion and femoral head under stress was smaller [30]. Even though higher rigidity was reported to reduce the amount of damage observed at the trunnion interface [30] on surfaces with comparable morphologies [31], the changes in contact pressure distribution led to higher stress intensification at the top of the trunnion which reduced the expected ultimate load during burst testing because the critical contact pressure was reached at lower applied loads [32].…”

Section: Burst-strength Test Results and Post Fracture Head Reconstrumentioning

confidence: 99%

Burst Strength of BIOLOX®delta Femoral Heads and Its Dependence on Low-Temperature Environmental Degradation

et al. 2020

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Zirconia-toughened alumina (ZTA) currently represents the bioceramic gold standard for load-bearing components in artificial hip joints. ZTA is long known for its high flexural strength and fracture toughness, both properties arising from a microscopic crack-tip shielding mechanism due to the stress-induced tetragonal-to-monoclinic (t→m) polymorphic transformation of zirconia. However, there have been concerns over the years regarding the long-term structural performance of ZTA since the t→m transformation also spontaneously occurs at the material’s surface under low-temperature environmental conditions with a concomitant degradation of mechanical properties. Spontaneous surface degradation has been extensively studied in vitro, but predictive algorithms have underestimated the extent of in vivo degradation observed in retrievals. The present research focused on burst-strength assessments of Ø28 mm ZTA femoral before and after long-term in vitro hydrothermal ageing according to ISO 7206-10. An average burst strength of 52 kN was measured for pristine femoral heads. This value was ~36% lower than results obtained under the same standard conditions by other authors. A further loss of burst strength (~13% in ultimate load) was observed after hydrothermal ageing, with increased surface monoclinic content ranging from ~6% to >50%. Nevertheless, the repetitively stressed and hydrothermally treated ZTA heads exceeded the minimum burst strength stipulated by the US Food and Drug Administration (FDA) despite severe test conditions. Lastly, Raman spectroscopic assessments of phase transformation and residual stresses on the fracture surface of the femoral heads were used to clarify burst-strength fluctuations and the effect of hydrothermal ageing on the material’s overall strength degradation.

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Section: Burst-strength Test Results and Post Fracture Head Reconstrumentioning

confidence: 99%

Burst Strength of BIOLOX®delta Femoral Heads and Its Dependence on Low-Temperature Environmental Degradation

et al. 2020

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“…A previously developed three dimensional FE model of the head-neck junction [17], which was verified by a set of experimental results (reported in [24]), was further developed to investigate the mechanical behaviour of the junction subjected to the loads associated with six different activities of daily living: knee bending, sit to stand, stand to sit, stair up, stair down and one leg standing. It is noted that the results for walking are presented and discussed in Part 1; however, some comparisons and discussions are reported in this part.…”

Section: Methodsmentioning

confidence: 99%

“…Maruyama et al. [6] performed pin-on-disc tests to study the fretting wear behaviour of a CoCr head and Although direct measurements of the mechanical environment are difficult, finite element (FE) analysis can be used to gain an understanding of the contact pressure and micro-motion throughout an activity [15][16][17]. The mechanical behaviour of the head-neck junction was investigated by Donaldson et al [18] using a stochastic finite element model.…”

Section: Introductionmentioning

confidence: 99%

“…Farhoudi et al [22] developed an analytical method to determine bending and torsional moments acting on the head-neck junction as a result of frictional sliding between the head and cup. Although there have been several studies on the geometric parameters and also loading parameters such as assembly force [23,24], strength of the headneck junction against torsional moments [17,25] and mechanical behaviour of the junction subjected to walking cyclic loading [18], the influence of the loading regimes caused by different physical daily activities on the mechanical environment of the head-neck junction has not been investigated yet. Furthermore, the effect of the bending and torsional moments produced by the frictional sliding of the head and cup on the mechanical response of the head-neck junction is still unknown.…”

Section: Introductionmentioning

confidence: 99%

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A finite element study on the mechanical response of the head-neck interface of hip implants under realistic forces and moments of daily activities: Part 2

Fallahnezhad

Farhoudi

Oskouei

et al. 2018

Journal of the Mechanical Behavior of Biomedical Materials

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A finite element model was developed to investigate the effect of loading regimes caused by various daily activities on the mechanical behaviour of the head-neck taper junction in modular hip replacements. The activities included stair up, stair down, sit to stand, stand to sit, one leg standing and knee bending. To present the real mechanical environment of the junction, in addition to the force components, the frictional moments produced by the frictional sliding of the head and cup were applied to a CoCr/CoCr junction having a 12/14 taper with a proximal mismatch angle of 0.024°. This study revealed that stair up with the highest fretting work per unit of length (1.62 × 10J/m) was the most critical activity, while knee bending and stand to sit with 1.96 × 10J/m were the least critical activities. For all the activities, the superolateral region of the neck was identified as the most critical region in terms of having larger values of fretting work per unit of area. This study showed also that the relative micro-motions and contact stresses occurring at the head-neck interface for all the studied activities are mostly in the range of 0-38µm and 0-350MPa, respectively. These ranges may be accordingly employed for conducting relevant in-vitro tests to more realistically represent the mechanical environment of taper junctions with the same materials and geometry studied in this work.

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“…Mechanical loads can contribute to implant failure via different mechanisms such as fretting-corrosion at the head-neck junction [1,2], loosening of the acetabular cup and femoral stem interface [3], fracture due to fatigue [4], and wear of hard-on-soft or hard-on-hard bearing couples [5,6]. The mechanical loads resulting from activities of daily living induce contact forces, frictional moments, and bending moments on the implant and its interfaces [7,8].…”

Section: Introductionmentioning

confidence: 99%

An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities

et al. 2016

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This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm) while normal walking had the smallest range (6.1 Nm). The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface.

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Influence of geometry and materials on the axial and torsional strength of the head–neck taper junction in modular hip replacements: A finite element study

Cited by 36 publications

References 25 publications

Burst Strength of BIOLOX®delta Femoral Heads and Its Dependence on Low-Temperature Environmental Degradation

Burst Strength of BIOLOX®delta Femoral Heads and Its Dependence on Low-Temperature Environmental Degradation

A finite element study on the mechanical response of the head-neck interface of hip implants under realistic forces and moments of daily activities: Part 2

An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities

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