Influence of flexural rigidity on micromotion at the head-stem taper interface of modular hip prostheses

Haschke, Henning; Konow, Tobias; Huber, Gerd; Morlock, Michael M.

doi:10.1016/j.medengphy.2019.03.020

Cited by 20 publications

(25 citation statements)

References 44 publications

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“…In the present study, the influence of taper length (83% for A vs B) might be secondary to taper angle and material stiffness with regard to observed micromotion, as more pistoning was expected for longer tapers. 42 Nevertheless, the consequences of higher micromotion remain unclear. Although Ti stems showed higher micromotion, they are used far more often in clinics.…”

Section: Discussionmentioning

confidence: 99%

Do SiNx coatings bear the potential to reduce the risk of micromotion in modular taper junctions?

Haschke

Falkenberg

Morlock

et al. 2020

Proc Inst Mech Eng H

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Fretting corrosion is one contributor to the clinical failure of modular joint arthroplasty. It is initiated by micromotion in metal junctions exposed to fluids. Omitting metal-on-metal contacts could help to reduce the corrosion risk. The coating of one metal taper partner with a ceramic-based silicon nitride (SiNx) coating might provide this separation. The aim of the study was to identify whether a SiNx coating of the male taper component influences the micromotion within a taper junction. Hip prosthesis heads made of CoCr29Mo6 (Aesculap) and Ti6Al4V (Peter Brehm) were assembled (2000 N) to SiNx-coated and uncoated stem tapers made of Ti6Al4V and CoCr29Mo6 (2×2×2 combinations, each n = 4). Consecutive sinusoidal loading representing three daily activities was applied. Contactless relative motion in six degrees of freedom was measured using six eddy-current sensors. Micromotion in the junction was determined by compensating for the elastic deformation derived from additional monoblock measurements. After pull-off, the taper surfaces were microscopically inspected. Micromotion magnitude reached up to 8.4 ± 0.8 µm during loading that represented stumbling. Ti6Al4V stems showed significantly higher micromotion than those made of CoCr29Mo6, while taper coating had no influence. Statistical differences in pull-off forces were found for none of the taper junctions. Microscopy revealed CoCr29Mo6 abrasion from the head taper surface if combined with coated stem tapers. Higher micromotion of Ti6Al4V tapers was probably caused by the lower Young’s modulus. Even in the contact areas, the coating was not damaged during loading. The mechanics of coated tapers was similar to uncoated prostheses. Thus, the separation of the two metal surfaces with the objective to reduce in vivo corrosion appears to be achievable if the coating is able to withstand in vivo conditions. However, the hard ceramic-based stem coating lead to undesirable debris from the CoCr29Mo6 heads during loading.

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Section: Discussionmentioning

confidence: 99%

Do SiNx coatings bear the potential to reduce the risk of micromotion in modular taper junctions?

Haschke

Falkenberg

Morlock

et al. 2020

Proc Inst Mech Eng H

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“…First, procedures are increasingly being performed through small incisions [85], which may impair the proper cleaning and drying of the taper due to reduced exposure. Secondly, driven by the trend to increase the range of motion, there has been a reduction in the diameter of the neck and of the length of the tapers, which reduces flexural rigidity [65,73]. At the same time, head diameters have increased with the aim of reducing the risk of dislocation, along with an increasing range of motion [24,86,87], a change justified by the improved wear characteristics of highly cross-linked polyethylene and ceramic bearings [88][89][90].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, and perhaps somewhat counterintuitively, the length of the trunnion does not appear to have a significant impact on micromotion or fixation force [47,64]. Increased trunnionosis has also been linked with low flexural rigidity necks (i.e., those with increased elasticity) [65] and small taper Symptomatic trunnionosis appears to be associated with increased head offsets and longer neck lever arms [21,22,56,57]. Micro-grooved tapers, designed to improve stress distributions in ceramic heads, may increase the likelihood of corrosion when combined with metal heads [21,58,59].…”

Section: Technical Aspects Of Taper Connections In Hip Arthroplastymentioning

confidence: 99%

“…In addition, and perhaps somewhat counterintuitively, the length of the trunnion does not appear to have a significant impact on micromotion or fixation force [47,64]. Increased trunnionosis has also been linked with low flexural rigidity necks (i.e., those with increased elasticity) [65] and small taper angle differences [66]. However, all these parameters are associated with the chosen design of the prosthesis and may not be modifiable intraoperatively.…”

Section: Technical Aspects Of Taper Connections In Hip Arthroplastymentioning

confidence: 99%

“…In general, older designs have smaller offsets. When choosing stems with increased offsets, the reduced flexural rigidity of the neck or the taper should be avoided [65,73]. In our opinion, the traditional solution in THA in compensating offset loss with leg-lengthening should be re-evaluated and updated in light of the increasing awareness of trunnionosis.…”

Section: Patient-related Factors For Trunnionosismentioning

confidence: 99%

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What the Surgeon Can Do to Reduce the Risk of Trunnionosis in Hip Arthroplasty: Recommendations from the Literature

Rieker

Wahl

2020

Materials

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Trunnionosis, defined as wear and corrosion at the head-neck taper connection, is a cause of failure in hip arthroplasty. Trunnionosis is linked to a synergistic combination of factors related to the prosthesis, the patient, and the surgeon. This review presents analytical models that allow for the quantification of the impact of these factors, with the aim of providing practical recommendations to help surgeons minimize the occurrence of this failure mode. A tighter fit reduces micromotion and, consequently, fretting of the taper connection. The paramount parameters controlling the fixation force are the coefficient of friction and the impaction force. The influence of the head diameter, as well as of the diameter and angle of the taper, is comparatively small, but varus alignment of the taper and heads with longer necks are unfavourable under physiologic loads. The trunnion should be rinsed, cleaned, and dried carefully, while avoiding any contamination of the bore-the female counterpart within the head-prior to assembly. Biological debris, and even residual water, might critically reduce the fixation of the taper connection between the head and the neck. The impaction force applied to the components should correspond to at least two strong blows with a 500 g hammer, striking the head with an ad hoc impactor aligned with the axis of the taper. These strong blows should correspond to a minimum impaction force of 4000 N.

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A novel algorithm to efficiently calculate the impingement‐free range of motion of irregularly‐shaped total hip arthroplasty components

Feng

Tang

Zhang

et al. 2023

Journal Orthopaedic Research

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There is great difficulty in quickly calculating the impingement‐free range of motion (IFROM) of hip components with complex shapes after total hip arthroplasty. We have established a new algorithm to investigate the effect of different shapes of hip components on the IFROM and impingement‐free safe zone (IFSZ). Then find the best combination of hip prosthesis and the optimal mounting position of the elevated‐rim liner under different radiographic anteversion (RA) and radiographic inclination (RI) of the cup. We found the larger the opening angle of the beveled‐rim liner and the smaller the cross‐sectional area of the stem neck with an inverted teardrop cross‐sectional shape, the greater the IFROM of the hip component. The beveled‐rim liner in combination with the stem neck with an inverted teardrop‐shaped cross‐section could provide the greatest IFSZ (excluding the flat‐rim liner). The optimal orientation of the elevated‐rim liner was the posterior‐inferior side (RI ≤ 37°), posterior‐superior side (RI ≥ 45°), and posterior side (37° ≤ RI ≤ 45°). Our novel algorithm provides a solution to analyze the IFROM of any hip prosthesis with any complex shape. The shape and size of the cross‐section of the stem neck, the orientation of the elevated rim, and the shape and opening angle of the liner are all critical factors for the quantitative calculation of the IFROM and mounting safe zone of the prosthesis. Stem necks with inverted teardrop cross‐section and beveled‐rim liner improved the IFSZ. The optimal direction of the elevated rim is not constant but varies with RI and RA.

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Influence of flexural rigidity on micromotion at the head-stem taper interface of modular hip prostheses

Cited by 20 publications

References 44 publications

Do SiNx coatings bear the potential to reduce the risk of micromotion in modular taper junctions?

Do SiNx coatings bear the potential to reduce the risk of micromotion in modular taper junctions?

What the Surgeon Can Do to Reduce the Risk of Trunnionosis in Hip Arthroplasty: Recommendations from the Literature

A novel algorithm to efficiently calculate the impingement‐free range of motion of irregularly‐shaped total hip arthroplasty components

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