Effects of merged holes, partial thread removal, and offset holes on fatigue strengths of titanium locking plates

Muthusamy, Balraj; Chao, Ching‐Kong; Su, Shinyen Jason; Cheng, Cheng-Wen; Lin, Jinn

doi:10.1016/j.clinbiomech.2022.105663

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…Strategies based on Finite Element (FE) analyses are usually proposed to study the effect of a hole [ 4 , 16 , 27 ] or a notch [ 26 ] in the stress distribution of a bone plate. Moreover, FE analyses are often used for the calculation of the stress distribution in a static condition, to be inserted into commercial software for the evaluation of fatigue life through analytical methods [ 1 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Bone Plates Runout Prediction Through Tensile Strength and Geometric Properties for Regulatory Mechanical Testing

Bologna,

Audenino,

Terzini

2023

Ann Biomed Eng

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Mechanical tests on bone plates are mandatory for regulatory purposes and, typically, the ASTM F382 standard is used, which involves a four-point bending test setup to evaluate the cyclic bending fatigue performance of the bone plate. These test campaigns require a considerable financial outlay and long execution times; therefore, an accurate prediction of experimental outcomes can reduce test runtime with beneficial cost cuts for manufacturers. Hence, an analytical framework is here proposed for the direct estimation of the maximum bending moment of a bone plate under fatigue loading, to guide the identification of the runout load for regulatory testing. Eleven bone plates awaiting certification were subjected to a comprehensive testing campaign following ASTM F382 protocols to evaluate their static and fatigue bending properties. An analytical prediction of the maximum bending moment was subsequently implemented based on ultimate strength and plate geometry. The experimental loads obtained from fatigue testing were then used to verify the prediction accuracy of the analytical approach. Results showed promising predictive ability, with R2 coefficients above 0.95 in the runout condition, with potential impact in reducing the experimental tests needed for the CE marking of bone plates.

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Section: Introductionmentioning

confidence: 99%

Bone Plates Runout Prediction Through Tensile Strength and Geometric Properties for Regulatory Mechanical Testing

Bologna,

Audenino,

Terzini

2023

Ann Biomed Eng

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Interfragmentary compression force and fixation stability of lateral tibial plateau fractures in normal and osteoporotic bones

Jiang,

Xu,

et al. 2024

Journal Orthopaedic Research

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Lateral platform collapse in fixations of lateral tibial plateau fractures (TPFs) using either double‐lag screws fixation (DSF) or locking‐plate fixation (LPF) is not rare. This study aimed to explore the effect of enhancing the interfragmentary compression force (IFCF) on fixation stability in lateral TPFs in normal and osteoporotic bones using finite element analysis. Finite element models of DSF in normal bone and LPF in normal and osteoporotic bones were established to simulate the fixations of lateral TPF. After model validation, axial compressive forces of 500, 1000, 1500, and 2500 N to the tibial plateau along with an IFCF of 0, 100, 200, and 300 N were applied. The maximum axial micromotion of the lateral fragment (MAM‐LF), maximal translational micromotion of the lateral fragment (MTM‐LF), peak von Mises stress (VMS), and peak equivalent elastic strain of the lateral fragment (EES‐LF) were evaluated. The MAM‐LF showed a decreasing trend as the IFCF increased in all models. For DSF models, the peak VMS of implants increased as the IFCF increased when the axial loads were 500 and 1000 N. The peak EES‐LF decreased as the IFCF increased under axial loads of 1000, 1500, and 2500 N. For the normal and osteoporotic LPF models, the peak VMS of the implants decreased as the IFCF increased. Peak EES‐LF decreased as IFCF increased. In conclusion, enhancing IFCF was beneficial in improving the fixation stability of lateral TPF. The optimal IFCF for DSF and LPF should be as high as reasonably feasible.

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An analytical and in silico strategy for estimating maximum stress and fatigue life of bone plates under in vivo loads: a rationale for regulatory testing

Bologna,

Audenino,

Terzini

2023

Front. Med. Eng.

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Despite the innovations introduced by locking compression plates (LCP), implant failures still occur due to fatigue fractures caused by cyclic loads. The endurance of LCP, especially in lower limb plates subjected to ambulatory cyclic loads, is a critical factor that needs to be understood. Unfortunately, there is limited information available on the fatigue failure of LCP. The fatigue behavior is a crucial aspect of mandatory mechanical tests for regulatory purposes, which aim to determine the load at which the plate withstands under a specific number of cycles, known as the runout condition. The current test standards, such as ASTM F382, only provide the setup configuration without furnishing explicit guidelines regarding the required fatigue strength of the bone plate in the runout condition. The determination of the minimum level of in vivo performance that the plate must fulfill remains an open issue, which is frequently addressed by the direct comparison with predicate devices. To address this issue, this study proposes a rationale that combines analytical and in silico approaches to estimate the maximum stress and fatigue life of a bone plate under in vivo loads. Four-point bending tests were conducted on a diaphyseal femoral plate to determine the experimental runout load. Analytical and finite element (FE) models were first implemented to replicate the four-point bending setup and to calculate the maximum stress on the plate. The Goodman and Gerber criteria were exploited to determine the mean stress effect due to the four-point bending setup and to verify the predicted number of cycles. In addition, the force-displacement curves of the FE model were validated by means of experimental results. Analytical and FE models were then applied to calculate the maximum stress and assess the performance of the implanted plate under in vivo loading conditions. In the implanted plate condition, a mean number of cycles higher than 1.5 million was estimated. Analytical models showed good performance compared with in silico strategies, exhibiting errors below 6%. The comparison between the obtained results provides valuable insights for constructing a robust rationale to support the regulatory process in order to obtain CE marking.

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Effects of merged holes, partial thread removal, and offset holes on fatigue strengths of titanium locking plates

Cited by 3 publications

References 25 publications

Bone Plates Runout Prediction Through Tensile Strength and Geometric Properties for Regulatory Mechanical Testing

Bone Plates Runout Prediction Through Tensile Strength and Geometric Properties for Regulatory Mechanical Testing

Interfragmentary compression force and fixation stability of lateral tibial plateau fractures in normal and osteoporotic bones

An analytical and in silico strategy for estimating maximum stress and fatigue life of bone plates under in vivo loads: a rationale for regulatory testing

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