The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis

Goebel, Paul; Kluess, Daniel; Wieding, Jan; Souffrant, Robert; Heyer, Horst; Sander, Manuela; Bader, Rainer

doi:10.1007/s00776-012-0340-7

Cited by 37 publications

(46 citation statements)

References 26 publications

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“…Recommendations widely appear to be based on a multitude of clinical factors, such as the size of the acetabulum [17], as well as on the surgeon's subjective evaluation. While sufficient stability of the implant is desirable for long-term performance [15], extensive deformation of the acetabular cup [4,21] has to be avoided to allow for concentric seating of the liner [1] and for sufficient clearance between the acetabular component and the femoral head [10].…”

Section: Discussionmentioning

confidence: 99%

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Basic considerations for determining the amount of press fit in acetabular cup endoprostheses as a function of the elastic bone behavior

Winter

Karl

2014

Biomedical Engineering / Biomedizinische Technik

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Acetabular cup endoprostheses are frequently placed in pelvic bone, employing the mechanical principle of press fit. While a sufficiently stable bone-implant connection is desirable, deformation of the cup and fracture of the pelvis should be avoided. The goal of this work is to demonstrate the importance of the elastic properties of bone on the amount of press fit achievable in a specific situation. On the basis of previous work describing the relation between relative bone mineral density and relative elastic modulus for cortical and trabecular bone, mechanical equations were used for analyzing the press-fit loading situation of an acetabular cup. Additionally, a two-dimensional finite element model was used for visualizing the stress and strain situation in the host bone occurring as a consequence of implant insertion, as well as the effect of moment loads acting on the acetabular cup. Given the fact that oversizing the implant for a specific recipient site is the only clinical means of optimizing press fit, knowledge of the elastic properties of the host bone before implant selection would be beneficial. Such information could, for instance, be derived from intraoperative compressive testing of the host bone.

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Section: Discussionmentioning

confidence: 99%

“…When the cup is press fit into the acetabulum, deformation of the cup occurs [4,10,21], which may result in an ill-fitting liner [1], reduced clearance between the liner and ball head [4,10,12,26], increased friction [19], and wear and subsequent component failure [21].…”

Section: Introductionmentioning

confidence: 99%

Basic considerations for determining the amount of press fit in acetabular cup endoprostheses as a function of the elastic bone behavior

Winter

Karl

2014

Biomedical Engineering / Biomedizinische Technik

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“…The second contact was defined between the shell and the liner, where a friction coefficient of 0.16 was applied [30]. The third contact was defined between the liner and the ball head, with a friction coefficient of 0.05 [13].…”

Section: Methodsmentioning

confidence: 99%

“…In particular, shells made of pure PEEK without reinforcement were deformed excessively, resulting in strong deformations of the liners, which might cause further problems in vivo. Excessive liner deformations can lead to a reduced clearance between the liner and femoral ball head and subsequently to increased frictional torques and increased wear rates [13][14][15][16]. Moreover, the seating of the liner might be jeopardized by strong shell deformations [17,18], which might lead to increased peak stresses within ceramic liners and, therefore, an increased risk of fracture [19][20][21].…”

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confidence: 99%

Influence of the Acetabular Cup Material on the Shell Deformation and Strain Distribution in the Adjacent Bone—A Finite Element Analysis

et al. 2020

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In total hip arthroplasty, excessive acetabular cup deformations and altered strain distribution in the adjacent bone are potential risk factors for implant loosening. Materials with reduced stiffness might alter the strain distribution less, whereas shell and liner deformations might increase. The purpose of our current computational study was to evaluate whether carbon fiber-reinforced poly-ether-ether-ketones with a Young´s modulus of 15 GPa (CFR-PEEK-15) and 23 GPa (CFR-PEEK-23) might be an alternative shell material compared to titanium in terms of shell and liner deformation, as well as strain distribution in the adjacent bone. Using a finite element analysis, the press-fit implantation of modular acetabular cups with shells made of titanium, CFR-PEEK-15 and CFR-PEEK-23 in a human hemi-pelvis model was simulated. Liners made of ceramic and polyethylene were simulated. Radial shell and liner deformations as well as strain distributions were analyzed. The shells made of CFR-PEEK-15 were deformed most (266.7 µm), followed by CFR-PEEK-23 (136.5 µm) and titanium (54.0 µm). Subsequently, the ceramic liners were radially deformed by up to 4.4 µm and the polyethylene liners up to 184.7 µm. The shell materials slightly influenced the strain distribution in the adjacent bone with CFR-PEEK, resulting in less strain in critical regions (<400 µm/m or >3000 µm/m) and more strain in bone building or sustaining regions (400 to 3000 µm/m), while the liner material only had a minor impact. The superior biomechanical properties of the acetabular shells made of CFR-PEEK could not be determined in our present study.Materials 2020, 13, 1372 2 of 16 ceramic and UHMWPE liners combined with structurally identical metallic shells were compared [6]. Therefore, the shell material of modular acetabular cups might have a stronger influence on the strain distribution than the liner material and shells made of polymers might have a lower influence on strain distribution.Besides UHMWPE, poly-ether-ether-ketone (PEEK), often applied with carbon fibers for reinforcement (CFR-PEEK), is a biocompatible polymer that has been introduced as a material for monolithic cups and liners, but not as a material for acetabular shells [7][8][9][10][11].However, PEEK and CFR-PEEK might be suitable alternatives to metal shells in modular acetabular cups as well, in order to avoid adverse effects on stress and strain distribution within the bone stock. However, it was shown that the reduced stiffness of shells made of PEEK and CFR-PEEK leads to increased shell deformations in the case of press-fit fixation in a finite element analysis (FEA) [12]. In particular, shells made of pure PEEK without reinforcement were deformed excessively, resulting in strong deformations of the liners, which might cause further problems in vivo. Excessive liner deformations can lead to a reduced clearance between the liner and femoral ball head and subsequently to increased frictional torques and increased wear rates [13][14][15][16]. Moreover, the seating of the liner might be j...

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“…This eccentricity is termed 'clearance', and is important to ensure smooth tribology, as it prevents jamming and facilitates lubrication with synovial fluid (19)(20)(21)(22)(23)(24)(25). Each bearing couple has a unique clearance, which depends on its articular diameter and materials.…”

Section: Introductionmentioning

confidence: 99%

Quantification of clearance and creep in acetabular wear measurements

Saffarini¹,

Grégory²,

Vandenbussche³

2016

Ann. Transl. Med.

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Background: This study aimed to measure femoral head penetration before occurrence of real wear, and to quantify the portions attributable respectively to clearance and plastic deformations in various acetabular designs. Methods:We analyzed CT scans from 15 patients at 'day five' after total hip arthroplasty (THA). All patients received Exafit ® femoral stems and 28 mm heads: 5 patients had cemented Durasul ® all-PE cups, 5 patients had uncemented Allofit ® metal-backed cups, and 5 patients had un-cemented Stafit ® dual-mobility cups. We also analyzed CT scans of samples of the three head-cup combinations to compare in vivo and in vitro measurements. Results:The mean femoral head penetration measured on 'day five' was lower for all-PE cups (0.196 mm) than for metal-backed cups (0.551 mm) and dual-mobility cups (0.634 mm). Conclusions:The present study indicates that isolated measurements of femoral head penetration include 0.15-0.46 mm of radial clearance and 0.05-0.27 mm of creep, and confirms that the majority of so-called beddingin observed in the first post-operative months is not entirely due to wear.

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The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis

Cited by 37 publications

References 26 publications

Basic considerations for determining the amount of press fit in acetabular cup endoprostheses as a function of the elastic bone behavior

Basic considerations for determining the amount of press fit in acetabular cup endoprostheses as a function of the elastic bone behavior

Influence of the Acetabular Cup Material on the Shell Deformation and Strain Distribution in the Adjacent Bone—A Finite Element Analysis

Quantification of clearance and creep in acetabular wear measurements

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