Accepted Manuscript Does Taper Size Have an Effect on Taper Damage in Retrieved Metal-onPolyethylene Total Hip Devices? Genymphas B. Higgs, M.S., Daniel W. MacDonald, M.S., Jeremy L. Gilbert, Ph.D., Clare M. Rimnac, Ph.D., Steven M. Kurtz, Ph.D. PII:
S0883-5403(16)30347-3
DOI:
10.1016/j.arth.2016.06.053
Reference:
YARTH 55290
To appear in:
The Journal of Arthroplasty
Received Date: 2 December 2015 Revised Date:
20 June 2016
Accepted Date: 26 June 2016
Please cite this article as: Higgs GB, MacDonald DW, Gilbert JL, Rimnac CM, Kurtz SM, and the Implant Research Center Writing Committee, Does Taper Size Have an Effect on Taper Damage in Retrieved Metal-on-Polyethylene Total Hip Devices?, The Journal of Arthroplasty (2016), doi: 10.1016/ j.arth.2016.06.053. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Does Taper Size Have an Effect on Taper Damage in Retrieved Metal-on-Polyethylene Total Hip Devices?
Daniel W. MacDonald, M.S.1 Jeremy L. Gilbert, Ph.D. 2 Clare M. Rimnac, Ph.D. 3 Steven M. Kurtz, Ph.D. 1,4
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Genymphas B. Higgs, M.S.1
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and the Implant Research Center Writing Committee*
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1. School of Biomedical Engineering, Science and Health Systems Drexel University Philadelphia, PA 19104 2. Department of Biomedical and Chemical Engineering Syracuse University Syracuse, NY 13210 3. Mechanical and Aerospace Engineering Department of Orthopaedics Case Western Reserve University Cleveland, Ohio 44106 4. Exponent, Inc. Philadelphia PA, 19104
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Please address all correspondence to: Genymphas Higgs School of Biomedical Engineering, Science and Health Systems Drexel University 3401 Market Street, Suite 345 Philadelphia, PA 19104
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Phone: (215) 571 4345 Email:
[email protected]
*The Implant Research Center Writing Committee consists of: Antonia F. Chen Gregg R. Klein Brian R. Hamlin Gwo-Chin Lee Michael A. Mont Harold E. Cates Arthur L. Malkani Matthew J. Kraay
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Does Taper Size Have an Effect on Taper Damage in Retrieved Metal-on-Polyethylene Total
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Hip Devices? Abstract:
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Background: Taper design has been identified as a possible contributor to fretting corrosion
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damage at modular connections in total hip arthroplasty systems, but variations in as-
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manufactured taper interfaces may confound this analysis. This study characterized taper damage
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in retrievals with two different taper sizes but comparable taper surface finishes and investigated if
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fretting and corrosion damage is related to taper size in the context of a multivariable analysis for
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metal-on-polyethylene bearings.
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Methods: A total of 252 CoCr femoral heads were identified in a collection of retrievals: 77 with
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Taper A and 175 with Taper B. Implantation time averaged 5.4 ± 6.0 years (range, 0 to 26 years).
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Explants were cleaned and analyzed using a 4-point semi-quantitative method. Clinical and device
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factors related to head taper fretting corrosion damage were assessed using ordinal logistic
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regression with forward stepwise control. Components were then selected to create two balanced
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cohorts, matched on significant variables from the multivariable analysis.
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Results: Increased head offset (p < 0.001), longer implantation time (p = 0.002), heavier patients (p
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< 0.001), and more flexible tapers (p < 0.001) were associated with increased taper fretting and
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corrosion damage. When damage scores were compared between the balanced groups, no
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significant differences were found.
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Conclusion: These results suggest that fretting and corrosion damage is insensitive to differences in
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taper size. The final model derived explains almost half of the fretting corrosion damage observed
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and identifies contributing factors that are consistent with other in vitro and retrieval studies.
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Introduction:
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There is considerable interest within the orthopaedic community in understanding the multifactorial
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process of modular component fretting corrosion in total hip arthroplasty (THA). Previous studies
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analyzing surgically retrieved hip devices have identified some patient and device factors
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associated with in vivo taper damage, including length of implantation, stem flexural rigidity, and
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head offset [1-5]. The increased incidence of taper-related complications in THA has also been
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attributed to the evolution of taper design [6]. Among implant manufacturers, narrower and
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shorter stem taper designs have been introduced to achieve increased range of joint motion while
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decreasing the risk of impingement and dislocation [7]. However, it has been hypothesized that
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these designs may experience more severe fretting corrosion because a smaller taper experiences
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greater stress for a given load [8]. Fretting corrosion is understood to be a synergistic mechanical
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and electrochemical phenomenon: increased localized stress may make the passive oxide film
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more likely to fracture, which compromises the corrosion-resistance of the interface [9].
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Understanding the effect of smaller tapers is complicated, as size is often not the only variable
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that can change between designs. In an experimental study that measured the taper angle of
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retrieved THA devices, commonly used taper options had angles of 4º, 5.6º, and 6º [10]. The
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surface finish of the taper may also vary, as some contemporary stem tapers have surface ridges
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in a grooved or threaded pattern [3, 7, 10-12]. It has been reported that during head impaction,
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deformation of these ridges limits the local stress concentration that results from a mismatch in
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cone geometry tolerances [12]. This provides a stress distribution that is particularly favorable
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for ceramic heads; however, these ridges have also been shown to leave imprints within metal
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heads via localized corrosion mechanisms [11, 12].
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The purpose of this study was to identify the effect that taper size has on taper damage while
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controlling for other variations in taper design. From a single manufacturer (Stryker Orthopaedics,
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Mahwah, New Jersey), we identified two different taper sizes that were fashioned with similar taper
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angles and comparable surface finishes. The C-Taper is based on the 12/14 Euro taper design,
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whereas, the V40 taper was designed with 8% less taper length and approximately 20% lower
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surface area (Figure 1). Both taper designs have a similar taper angle of 5° 40’ and a smooth surface
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finish (surface profile with a wavelength
