Inadequate Metadiaphyseal Fill of a Modern Taper-Wedge Stem Increases Subsidence and Risk of Aseptic Loosening: Technique and Distal Canal Fill Matter!

Warth, Lucian C.; Grant, Tanner W.; Naveen, Neal B.; Deckard, Evan R.; Ziemba-Davis, Mary; Meneghini, R. Michael

doi:10.1016/j.arth.2020.02.024

Cited by 25 publications

(16 citation statements)

References 43 publications

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“…Aside from its increased compliance and the need for a powder drainage hole, this novel selectively hollowed stem is indistinguishable from the solid counterpart ( Figure 5 ), which may aid clinical translation, where each design change requires extensive testing and validation prior to clinical trial. For example, there is a complex interplay between broach design, technique and the stem to ensure suitable initial implant fixation [ 52 , 53 ]. Changing the outside shape of the stem would require the design of a new broach and re-validation to ensure that the desired fixation is achieved.…”

Section: Discussionmentioning

confidence: 99%

Topology Optimisation for Compliant Hip Implant Design and Reduced Strain Shielding

Tan

Arkel

2021

Materials

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Stiff total hip arthroplasty implants can lead to strain shielding, bone loss and complex revision surgery. The aim of this study was to develop topology optimisation techniques for more compliant hip implant design. The Solid Isotropic Material with Penalisation (SIMP) method was adapted, and two hip stems were designed and additive manufactured: (1) a stem based on a stochastic porous structure, and (2) a selectively hollowed approach. Finite element analyses and experimental measurements were conducted to measure stem stiffness and predict the reduction in stress shielding. The selectively hollowed implant increased peri-implanted femur surface strains by up to 25 percentage points compared to a solid implant without compromising predicted strength. Despite the stark differences in design, the experimentally measured stiffness results were near identical for the two optimised stems, with 39% and 40% reductions in the equivalent stiffness for the porous and selectively hollowed implants, respectively, compared to the solid implant. The selectively hollowed implant’s internal structure had a striking resemblance to the trabecular bone structures found in the femur, hinting at intrinsic congruency between nature’s design process and topology optimisation. The developed topology optimisation process enables compliant hip implant design for more natural load transfer, reduced strain shielding and improved implant survivorship.

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Section: Discussionmentioning

confidence: 99%

Topology Optimisation for Compliant Hip Implant Design and Reduced Strain Shielding

Tan

Arkel

2021

Materials

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“…( 4 ) Clinical femoral stem subsidence may result in failure of implant osseointegration. ( 5 ) Consequently, there is a tremendous incentive to identify factors that improve primary femoral stem stability.…”

Section: Introductionmentioning

confidence: 99%

Denosumab in Cementless Total Hip Arthroplasty: Multivariate Reanalysis of 3D Femoral Stem Migration and the Influence on Outliers

2021

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In cementless total hip arthroplasty, adequate implant stability is necessary for the success of osseointegration and rapid clinical recovery. Postoperative femoral stem migration, measured by radiostereometric analysis (RSA), defines the initial stability achieved during surgical implantation. In a recent trial of 65 postmenopausal women randomized 1:1 denosumab:placebo, denosumab failed to reduce the initial migration of a cementless femoral stem despite the successful prevention of periprosthetic bone loss. The trial applied the current RSA standard, which examined stem migration on an axis‐by‐axis basis and did not consider more complex three‐dimensional (3D) migration. Therefore, we performed a reanalysis of the trial data using a multivariate hierarchical linear mixed model (LMM). As an additional limitation, the data included influential outliers. Women with normal bone mineral density exhibited significantly (p = 0.036) less stem subsidence compared with osteopenic and osteoporotic women. Denosumab significantly decreased the variance of stem migration in osteopenic and osteoporotic women. The mean magnitude of 3D stem migration did not differ between denosumab‐treated and placebo‐treated women (p = 0.820). After application of a common statistical definition for RSA outlier identification, there were eight (12%) outliers, six in the placebo group and two in the denosumab group (p = 0.149). After exclusion of the outliers, the repeated LMM analysis demonstrated a trending difference in 3D stem migration (p = 0.086), with a significant difference of z‐axis rotation (valgus‐varus tilt) of the femoral stem (p = 0.029). The observed effect size was small and without clinically important differences in postoperative recovery. Based on a Monte Carlo simulation with random‐generated 3D migration data, multivariate LMM showed greater statistical power than univariate analyses. The application of hierarchical LMM facilitated the analysis of implant migration as a factual 3D event. The observed trend in the lower number of RSA outliers in denosumab‐treated subjects warrants powered large‐scale trials. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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“…In cementless total hip arthroplasty, adequate initial femoral stem stability is necessary for clinical success. Clinical subsidence, measurable from routine radiographs, predisposes femoral stems to early failure (Warth et al 2020). Avoiding undersizing the femoral stem with a meticulous broaching technique may minimize the risk of subsidence (Warth et al 2020).…”

mentioning

confidence: 99%

“…Clinical subsidence, measurable from routine radiographs, predisposes femoral stems to early failure (Warth et al 2020). Avoiding undersizing the femoral stem with a meticulous broaching technique may minimize the risk of subsidence (Warth et al 2020). The acceptable level of subsidence of cementless stems, as determined by radiostereometric analysis, is still unknown (van der Voort et al 2015).…”

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confidence: 99%

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Bone quality makes a difference

Aro

2021

Acta Orthopaedica

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Inadequate Metadiaphyseal Fill of a Modern Taper-Wedge Stem Increases Subsidence and Risk of Aseptic Loosening: Technique and Distal Canal Fill Matter!

Cited by 25 publications

References 43 publications

Topology Optimisation for Compliant Hip Implant Design and Reduced Strain Shielding

Topology Optimisation for Compliant Hip Implant Design and Reduced Strain Shielding

Denosumab in Cementless Total Hip Arthroplasty: Multivariate Reanalysis of 3D Femoral Stem Migration and the Influence on Outliers

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