A novel approach to determine primary stability of acetabular press-fit cups

Weißmann, Volker; Boss, Christian; Bader, Rainer; Hansmann, Harald

doi:10.1016/j.jmbbm.2018.01.015

Cited by 13 publications

(21 citation statements)

References 46 publications

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“…The goal of this study was to assess the relationship between two different initial stability tests; the golden standard test of micromotion versus alternative load-to-failure implant stability metrics derived from a push-out experiment. Different stability metrics were derived from the push-out experiment similarly to ones that are used in previous research; ultimate push-out force [7,30,31], interface stiffness [15,18], push-out energy [21,32]. A push-out experiment was chosen over other load-to-failure tests, as the applied load direction during a push-out test is similar to a physiologic loading direction.…”

Section: Discussionmentioning

confidence: 99%

Two Different Methods to Measure the Stability of Acetabular Implants: A Comparison Using Artificial Acetabular Models

Goossens

Pastrav

Mulier

et al. 2020

Sensors

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The total number of total hip arthroplasties is increasing every year, and approximately 10% of these surgeries are revisions. New implant design and surgical techniques are evolving quickly and demand accurate preclinical evaluation. The initial stability of cementless implants is one of the main concerns of these preclinical evaluations. A broad range of initial stability test methods is currently used, which can be categorized into two main groups: Load-to-failure tests and relative micromotion measurements. Measuring relative micromotion between implant and bone is recognized as the golden standard for implant stability testing as this micromotion is directly linked to the long-term fixation of cementless implants. However, specific custom-made set-ups are required to measure this micromotion, with the result that numerous studies opt to perform more straightforward load-to-failure tests. A custom-made micromotion test set-up for artificial acetabular bone models was developed and used to compare load-to-failure (implant push-out test) with micromotion and to assess the influence of bone material properties and press-fit on the implant stability. The results showed a high degree of correlation between micromotion and load-to-failure stability metrics, which indicates that load-to-failure stability tests can be an appropriate estimator of the primary stability of acetabular implants. Nevertheless, micromotions still apply as the golden standard and are preferred when high accuracy is necessary. Higher bone density resulted in an increase in implant stability. An increase of press-fit from 0.7 mm to 1.2 mm did not significantly increase implant stability.

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Section: Discussionmentioning

confidence: 99%

Two Different Methods to Measure the Stability of Acetabular Implants: A Comparison Using Artificial Acetabular Models

Goossens

Pastrav

Mulier

et al. 2020

Sensors

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“…The modified cups (Figure 1) were designed on the basis of a conventional press-fit cup with a pole flattening. The suitability of a modified press-fit cup (reduced height) for the use in a development phase was verified in an earlier study [50]. All cups were designed in a reduced design with an equatorial cup diameter of 55.3 mm and a pole flattening of 1 mm.…”

Section: Cup Designmentioning

confidence: 98%

“…The measurements of the following points were carried out extensively as described in Weißmann et al [50]. Here, the relevant points are briefly explained.…”

Section: Measurementsmentioning

confidence: 99%

“…This is mainly because of the reproducibility of the results, better availability and avoidance of ethical problems.In the context of this work, standard acetabular cups in the press-fit version were constructively provided with a porous layer on the surface to experimentally determine the influence on primary stability. The porous structures were applied to a reduced-acetabular cup, the suitability of which for the characterization of primary stability has been evaluated in a previous study [50]. All acetabular cups Metals 2018, 8, 839 3 of 21 were manufactured using additive manufacturing technology (Selective Laser Melting).…”

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confidence: 99%

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Experimental Characterization of the Primary Stability of Acetabular Press-Fit Cups with Open-Porous Load-Bearing Structures on the Surface Layer

Weißmann

Boss²,

Schulze

et al. 2018

Metals

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Background: Nowadays, hip cups are being used in a wide range of design versions and in an increasing number of units. Their development is progressing steadily. In contrast to conventional methods of manufacturing acetabular cups, additive methods play an increasingly central role in the development progress. Method: A series of eight modified cups were developed on the basis of a standard press-fit cup with a pole flattening and in a reduced version. The surface structures consist of repetitive open-pore load-bearing textural elements aligned right-angled to the cup surface. We used three different types of unit cells (twisted, combined and combined open structures) for constructing of the surface structure. All cups were manufactured using selective laser melting (SLM) of titanium powder (Ti6Al4V). To evaluate the primary stability of the press fit cups in the artificial bone cavity, pull-out and lever-out tests were conducted. All tests were carried out under exact fit conditions. The closed-cell polyurethane (PU) foam, which was used as an artificial bone cavity, was characterized mechanically in order to preempt any potential impact on the test results. Results and conclusions: The pull-out forces as well as the lever moments of the examined cups differ significantly depending on the elementary cells used. The best results in pull-out forces and lever-out moments are shown by the press-fit cups with a combined structure. The results for the assessment of primary stability are related to the geometry used (unit cell), the dimensions of the unit cell, and the volume and porosity responsible for the press fit. Corresponding functional relationships could be identified. The findings show that the implementation of reduced cups in a press-fit design makes sense as part of the development work.beyond the current state of the art, for example in the field of orthopedics, is an interesting task for development engineers. Due to their outstanding mechanical and biocompatible properties, titanium and titanium alloys, in addition to other materials, are at the center of development work [5][6][7].Of major interest is the implementation of open-porous structures in orthopedic implants. These structural elements provide excellent conditions to fulfil structural and functional requirements. Open-porous structures meet the mechanical requirements regarding surface quality as well as those regarding design conditions [8][9][10]. In addition, such structures offer a potential for solving the problems of different stiffnesses between human bone and full implants [11,12]. As a result of their geometry, open-pore structures offer the cells good conditions for nutrient supply, and consequently, the possibility to grow well into the pores. Characteristic features of open-pore structures like pore size and distribution as well as connectivity affect biological processes like cell migration and proliferation and as a result the regeneration process [3,13].The applications of open-porous and load-bearing structures in orthopedic ap...

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“…It was found that surface nanotexture technology improved the anti-cell viscosity of the implant surface and provided a new design for the surface modification of implants. Moreover, based on the mesoscale topological design, Weißmann et al [157] proposed an open-cell structure on the surface of the acetabular cup. Pull-out and lever-out tests results showed that the surface-modified implant has better stability, which reveals that proper surface topology helps to improve the stability of the implant.…”

Section: Surface Modificationmentioning

confidence: 99%

Additive Manufacturing of Customized Metallic Orthopedic Implants: Materials, Structures, and Surface Modifications

Bai

Cheng

Chen

et al. 2019

Metals

132

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Metals have been used for orthopedic implants for a long time due to their excellent mechanical properties. With the rapid development of additive manufacturing (AM) technology, studying customized implants with complex microstructures for patients has become a trend of various bone defect repair. A superior customized implant should have good biocompatibility and mechanical properties matching the defect bone. To meet the performance requirements of implants, this paper introduces the biomedical metallic materials currently applied to orthopedic implants from the design to manufacture, elaborates the structure design and surface modification of the orthopedic implant. By selecting the appropriate implant material and processing method, optimizing the implant structure and modifying the surface can ensure the performance requirements of the implant. Finally, this paper discusses the future development trend of the orthopedic implant.

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A novel approach to determine primary stability of acetabular press-fit cups

Cited by 13 publications

References 46 publications

Two Different Methods to Measure the Stability of Acetabular Implants: A Comparison Using Artificial Acetabular Models

Two Different Methods to Measure the Stability of Acetabular Implants: A Comparison Using Artificial Acetabular Models

Experimental Characterization of the Primary Stability of Acetabular Press-Fit Cups with Open-Porous Load-Bearing Structures on the Surface Layer

Additive Manufacturing of Customized Metallic Orthopedic Implants: Materials, Structures, and Surface Modifications

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