Stem taper mismatch has a critical effect on ceramic head fracture risk in modular hip arthroplasty

Background: Mixing and matching components from different manufacturers in total hip arthroplasty is a frequently used off-label praxis. The clinical consequences of this procedure have not been studied in detail. Methods: 860 patients with matched and 1067 patients with mixed primary total hip replacement (THR) components carried out between 1 January 2002 and 31 December 2004, were selected from our Institution registry. The analysis endpoint was set at 1 January 2016. THRs with poorly performing components were excluded from study groups. Kaplan-Meier survival curves for both groups were calculated and compared using the Log-Rank test and the demographic data using the chi-square test. Correlations between demographic data and revisions were calculated using bivariate correlation. Results: 28 revisions were carried out in the matched group and 67 in the mixed group. The 14-year overall survival probability was significantly better in the former (96.0%) than in the mixed group (92.7%) ( p = 0.002). Survival, free of aseptic and septic failures, was statistically, significantly higher in the matched group ( p = 0.026 and p = 0.007, respectively). The survival of the mixed subgroup with heads and stems from the same manufacturer did not differ statistically from that of the matched group ( p = 0.079). Conclusions: In contrast to the results listed in the National Joint Registry and the New Zealand Joint Registry, the survival probability in our study was, statistically, significantly higher in total hip replacements using components of the same manufacturer. Importantly, mixing and matching the components of different manufacturers led to similar survival providing the head and the stem were from the same manufacturer.

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“…A ceramic revision head can be used only with the appropriate titanium sleeve that must match the taper of the retained stem. 4–6…”

Section: Introductionmentioning

confidence: 99%

Survival rate of total hip replacements with matched and with mixed components with 10.7 years mean follow-up

et al. 2020

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“…In THAs with ceramic heads, a mismatch can result in a fracture of the femoral head component. 48 , 51 , 52 …”

Section: Recommendationsmentioning

confidence: 99%

“…It has been shown 52 that with mismatched components the mean fracture strength of the ceramic heads was reduced to about 50% of the recommended FDA strength.…”

Section: Recommendationsmentioning

confidence: 99%

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EFORT recommendations for off-label use, mix & match and mismatch in hip and knee arthroplasty

Tucker¹,

Günther

Kjærsgaard‐Andersen

et al. 2021

EFORT Open Reviews

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Off-label use is frequently practiced in primary and revision arthroplasty, as there may be indications for the application of implants for purposes outside the one the manufacturers intended. Under certain circumstances, patients may benefit from selective application of mix & match. This can refer to primary hip arthroplasty (if evidence suggests that the combination of devices from different manufacturers has superior results) and revision hip or knee arthroplasty (when the exchange of one component only is necessary and the invasiveness of surgery can be reduced). Within the EFORT ‘Implant and Patient Safety Initiative’, evidence- and consensus-based recommendations have been developed for the safe application of off-label use and mix & match in primary as well as revision hip and knee arthroplasty. Prior to the application of a medical device for hip or knee arthroplasty off-label and within a mix & match situation, surgeons should balance the risks and benefits to the patient, obtain informed consent, and document the decision process appropriately. Nevertheless, it is crucial for surgeons to only combine implants that are compatible. Mismatch of components, where their sizes or connections do not fit, may have catastrophic effects and is a surgical mistake. Surgeons must be fully aware of the features of the components that they use in off-label indications or during mix & match applications, must be appropriately trained and must audit their results. Considering the frequent practice of off-label and mix & match as well as the potential medico-legal issues, further research is necessary to obtain more data about the appropriate indications and outcomes for those procedures. Cite this article: EFORT Open Rev 2021;6:982-1005. DOI: 10.1302/2058-5241.6.210080

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“…The mechanical behavior of the taper connection is dependent on a number of parameters. The material combination used at the taper [6] and the taper mismatch angle [6][7][8][9] can be controlled by the design and the manufacturing process. The type of the mechanical load as a result of daily activities can also influence the mechanical behavior of the taper junction [10,11].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Assembly Force on the Material Loss at the Metallic Head-Neck Junction of Hip Implants Subjected to Cyclic Fretting Wear

Fallahnezhad

Oskouei

Badnava³

et al. 2019

Metals

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The impaction force required to assemble the head and stem components of hip implants is proven to play a major role in the mechanics of the taper junction. However, it is not clear if the assembly force could have an effect on fretting wear, which normally occurs at the junction. In this study, an adaptive finite element model was developed for a CoCr/CoCr head-neck junction with an angular mismatch of 0.01° in order to simulate the fretting wear process and predict the material loss under various assembly forces and over a high number of gait cycles. The junction was assembled with 2, 3, 4, and 5 kN and then subjected to 1,025,000 cycles of normal walking gait loading. The findings showed that material removal due to fretting wear increased when raising the assembly force. High assembly forces induced greater contact pressures over larger contact regions at the interface, which, in turn, resulted in more material loss and wear damage to the surface when compared to lower assembly forces. Although a high assembly force (greater than 4 kN) can further improve the initial strength and stability of the taper junction, it appears that it also increases the degree of fretting wear. Further studies are needed to investigate the assembly force in the other taper designs, angular mismatches, and material combinations.

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Stem taper mismatch has a critical effect on ceramic head fracture risk in modular hip arthroplasty

Cited by 14 publications

References 19 publications

Survival rate of total hip replacements with matched and with mixed components with 10.7 years mean follow-up

Survival rate of total hip replacements with matched and with mixed components with 10.7 years mean follow-up

EFORT recommendations for off-label use, mix & match and mismatch in hip and knee arthroplasty

The Influence of Assembly Force on the Material Loss at the Metallic Head-Neck Junction of Hip Implants Subjected to Cyclic Fretting Wear

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