Dataset Information

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis.

ABSTRACT:

Background

The objective is to compare, by the means of finite elements analysis, the biomechanical behavior of a conventional stem of proven performance with a short stem based on the same fixation principles.

Methods

A 3D femur was modeled from CT scan data, and real bone density measures were incorporated into it. Load stresses were applied to that bone in 3 different scenarios: without prosthesis, with the conventional stem, and with the short stem. Different bone loading patterns were compared by Gruen's zones both visually and statistically using Welch's test.

Results

The implantation of a stem generates a certain degree of stress shielding in the surrounding bone, but the pattern of the change is very similar in the compared stem models. Although there is statistical significance (P < 0.01) in the mean stress variation in most of the Gruen's zones, the magnitude of the difference is always under 2 MPa (range: 0.01 - 1.74 MPa).

Conclusions

The bone loading patterns of the traditional stem and the short stem are very similar. Although there is no evidence of a link between biomechanics and clinical outcomes, our results may suggest that theoretical advantages of short stems can be exploited without the fear of altering bone loading patterns.

SUBMITTER: Gomez-Vallejo J

PROVIDER: S-EPMC7856394 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis.

Gómez-Vallejo Jesús J Roces-García Jorge J Moreta Jesús J Donaire-Hoyas Daniel D Gayoso Óscar Ó Marqués-López Fernando F Albareda Jorge J

Arthroplasty today 20210201

<h4>Background</h4>The objective is to compare, by the means of finite elements analysis, the biomechanical behavior of a conventional stem of proven performance with a short stem based on the same fixation principles.<h4>Methods</h4>A 3D femur was modeled from CT scan data, and real bone density measures were incorporated into it. Load stresses were applied to that bone in 3 different scenarios: without prosthesis, with the conventional stem, and with the short stem. Different bone loading patt ...[more]

PMID: 33553545

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Project description:BACKGROUND:To compare the biomechanical properties of a novel height-adjustable nano-hydroxyapatite/polyamide-66 vertebral body (HAVB) with the titanium mesh cage (TMC) and artificial vertebral body (AVB), and evaluate its biomechanical efficacy in spinal stability reconstruction. METHODS:A 3D nonliner FE model of the intact L1-sacrum was established and validated. Three FE models which instrumented HAVB, TMC, and AVB were constructed for surgical simulation. A pure moment of 7.5 Nm and a 400-N preload were applied to the three FE models in 3D motion. The peak von Mises stress upon each prosthesis and the interfaced endplate was recorded for analysis. In addition, the overall and intersegmental range of motion (ROM) of each model was investigated to assess the efficacy of each model in spinal stability reconstruction. RESULTS:AVB had the greatest stress concentration compared with TMC and HAVB in all motions (25.6-101.8 times of HAVB, 0.8-8.1 times of TMC). The peak stress on HAVB was 3.1-10.3% of TMC and 1.6-3.9% of AVB. The maximum stress values on L2 caudal and L4 cranial endplates are different between the three FE models: 0.9-1.9, 1.3-12.1, and 31.3-117.9 times of the intact model on L2 caudal endplates and 0.9-3.5, 7.2-31.5, and 10.3-56.4 times of the intact model on L4 cranial endplates in HAVB, TMC, and AVB, respectively, while the overall and segmental ROM reduction was similar between the three models, with AVB providing a relatively higher ROM reduction in all loading conditions (88.1-84.7% of intact model for overall ROM and 69.5-82.1% for L1/2, 87.0-91.7% for L2/4, and 71.1-87.2% for L4/5, respectively). CONCLUSIONS:HAVB had similar biomechanical efficacy in spinal stability reconstruction as compared with TMC and AVB. The material used and the anatomic design of HAVB can help avoid stress concentration and the stress shielding effect, thus greatly reducing the implant-associated complications. HAVB exhibited some advantageous biomechanical properties over TMC and AVB and may prove to be a potentially viable option for spinal stability reconstruction. Further in vivo and vitro studies are still required to validate our findings and conclusions.

Project description:BackgroundTotal hip replacement has recently followed a progressive evolution towards principles of bone- and soft-tissue-sparing surgery. Regarding femoral implants, different stem designs have been developed as an alternative to conventional stems, and there is a renewed interest towards short versions of uncemented femoral implants. Based on both experimental testing and finite element modeling, the proposed study has been designed to compare the biomechanical properties and clinical performance of the newly introduced short-stem Minima S, for which clinical data are lacking with an older generation stem, the Trilock Bone Preservation Stem with an established performance record in short to midterm follow-up.Methods/designIn the experimental study, the transmission of forces as measured by cortical surface-strain distribution in the proximal femur will be evaluated using digital image correlation (DIC), first on the non-implanted femur and then on the implanted stems. Finite element parametric models of the bone, the stem and their interface will be also developed. Finite element predictions of surface strains in implanted composite femurs, after being validated against biomechanical testing measurements, will be used to assist the comparison of the stems by deriving important data on the developed stress and strain fields, which cannot be measured through biomechanical testing. Finally, a prospective randomized comparative clinical study between these two stems will be also conducted to determine (1) their clinical performance up to 2?years' follow-up using clinical scores and gait analysis (2) stem fixation and remodeling using a detailed radiographic analysis and (3) incidence and types of complications.DiscussionOur study would be the first that compares not only the clinical and radiological outcome but also the biomechanical properties of two differently designed femoral implants that are theoretically classified in the same main category of cervico-metaphyseal-diaphyseal short stems. We can hypothesize that even these subtle variations in geometric design between these two stems may create different loading characteristics and thus dissimilar biomechanical behaviors, which in turn could have an influence to their clinical performance.Trial registrationInternational Standard Randomized Controlled Trial Number, ID: ISRCTN10096716 . Retrospectively registered on May 8 2018.

Project description:BackgroundIn the follow-up after internal fixation of thoracolumbar fractures, the imaging of some patients shows "crater-like" collapse of the superior endplate of the injured vertebra, with variable collapse area and depth, even involving the anterior edge of the vertebral body. Though many papers had described the phenomenon, but nearly no one did biomechanical research about this. So we did this research in a creative way by using finite element model.MethodsA healthy male volunteer was selected. The 64-slice thin-section spiral computed tomography images at the level of T11-L3 were collected. Data were imported into Mimics 15.0 medical image processing software to establish three-dimensional finite element skeletal models of T11 to L3 containing only three-dimensional surface elements without entities. The model was assigned values and verified. Then the pedicle screw-rod system was added to this model, and five models containing the screw-rod system with different defect sizes as well as five models that simulated the removal of the screw-rod system were derived at the same time (the defect volume was 1/5, 2/5, 3/5, 4/5, or 5/5 of the anterior vertebral column, respectively). Biomechanical analysis was then performed on this basis.ResultsAfter the removal of the internal fixator, as defect volume increased, the stress difference between the 4/5 defect group and the 5/5 defect group had the greatest magnitude of combined stress under the seven working conditions. When the volume of the collapse defect reached 4/5 of the anterior column of the vertebral body, the concentration of stress increased significantly, suggesting that the risk of continued compression or even refracture of the injured vertebra increased if the internal fixator was removed at that time.ConclusionsWhen the volume of the defect in the superior endplate of the injured vertebra reaches 4/5 of the anterior column, the removal of the internal fixator should be carefully considered to avoid refracture of the anterior column of the injured vertebra.

Dataset Information

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis.

Background

Methods

Results

Conclusions

Publications

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis.

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