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Item type:Publication, Access status: with files , Head taper corrosion causing head bottoming out and consecutive gross stem taper failure in total hip arthroplasty(Elsevier, 2018-07-24); ; ; ; Taper corrosion in total hip arthroplasty for bearings with metal heads against polyethylene has developed from an anecdotal observation to a clinical problem. Increased taper wear and even gross taper failure have been reported for one particular design. It is hypothesized that corrosion of the female head taper results in taper widening, allowing the cobalt-chromium head to turn on the stem and wear down the softer titanium alloy by abrasive wear, ultimately causing failure. The purpose of this study is to investigate the time course of this process and the general role of taper dimensions and material in this problem.Publicationtype: Journal ArticleScopus© Citations 42 308 825 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The taper corrosion pattern observed for one bi-modular stem design is related to geometry-determined taper mechanics(2017-08); ; ; ; Bi-modular primary hip stems exhibit high revision rates owing to corrosion at the stem-neck taper, and are associated with local adverse tissue reactions. The aim of this study was to relate the wear patterns observed for one bi-modular design to its design-specific stem-neck taper geometry. Wear patterns and initial geometry of the taper junctions were determined for 27 retrieved bi-modular primary hip arthroplasty stems (Rejuvenate, Stryker Orthopaedics) using a tactile coordinate-measuring device. Regions of high-gradient wear patterns were additionally analyzed via optical and electron microscopy. The determined geometry of the taper junction revealed design-related engagement at its opening (angle mismatch), concentrated at the medial and lateral apexes (axes mismatch). A patch of retained topography on the proximal medial neck-piece taper apex was observed, surrounded by regions of high wear. On the patch, a deposit from the opposing female stem taper—containing Ti, Mo, Zr, and O—was observed. High stress concentrations were focused at the taper apexes owing to the specific geometry. A medial canting of the components may have augmented the inhomogeneous stress distributions in vivo. In the regions with high normal loads interfacial slip and consequently fretting was inhibited, which explains the observed pattern of wear.Publicationtype: Journal Article223 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Surface and subsurface changes as a result of tribocorrosion at the stem-neck interface of bi-modular prosthesis(2017-06); ; ; ; This study presents a detailed multi-scale analysis of the degradation processes occurring on both the CoCrMo and TMZF alloy surfaces at different regions across the taper interface. Co-ordinate measurement machine, scanning electron microscopy, transmission electron microscopy and X-ray diffraction methods have been utilised to identify the roles of degradation from the mm to nm scale. Depending on the region of interest, varying topographies and subsurface morphologies were observed across both surfaces. In regions where high pressures are expected, retention of the surface topography was seen on the CoCrMo trunnion. This was complimented by gross shear and plastic deformation of the subsurface material. In regions where maximum penetration was seen, evidence of fretting-corrosion was seen and a loss of the nano-crystalline layer. For the TMZF surface, refinement of the alloy was seen in the top 5 μm, with fatigue cracks within the bulk present. Precipitation and formation of oxide species were observed at depths of 2 μm. The degradation of a bi-modular prosthesis is a complex multifactorial process. It is hypothesised that this formation of oxide species at the interface and within the bulk alloy plays an important role in the degradation through a combined work-hardening and corrosion process.Publicationtype: Journal Article134 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Corrosion of the Head-Stem Taper Junction—Are We on the Verge of an Epidemic?: Review Article(2017-02-01); ; ; Background: The modular head taper junction has contributed to the success of total hip arthroplasty (THA) greatly. Taper corrosion and wear problems reported for large and extra-large metal-on-metal bearings as well as for bi-modular THA stems have cast doubt on the benefit of the taper interface. Presently, corrosion problems are being reported for nearly all kinds of artificial hip joints incorporating metal heads, questioning taper connections in general. Questions/purposes: This study aimed to review the mechanical and electrochemical relationships that may lead to taper corrosion, which have been reported more commonly in recent literature, and to also review the contribution of patient characteristics and surgical techniques involved in taper assembly that may contribute to the problem. Methods: The search criteria “(corrosion) AND (hip arthroplasty) AND (taper OR trunnion)” and “(hip arthroplasty) AND ((pseudotumor) OR (pseudo-tumor))” in PubMed and the JAAOS were used for the literature search. In addition, the arthroplasty registers were considered. Results: Most studies acknowledge the multifactorial nature of the problem but concentrate their analysis on taper and implant design aspects, since this is the only factor that can be easily quantified. The sometimes conflicting results in the literature could be due to the fact that the other two decisive factors are not sufficiently considered: the loading situation in the patient and the assembly situation by the surgeon. All three factors together determine the fate of a taper junction in THA. There is no single reason as a main cause for taper corrosion. The combined “outcome” of these three factors has to be in a “safe range” to achieve a successful long-term taper fixation. Conclusion: No, this is not the beginning of an epidemic. It is rather the consequence of disregarding known mechanical and electrochemical relationships, which in combination have recently caused a more frequent occurrence—and mainly reporting—of corrosion issues.Publicationtype: Review Article70 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fretting-Korrosion modularer Hüftendoprothesen(2017); Early failure of total hip replacements can be caused by the release of wear products from modular junctions due to fretting-corrosion. The aim was to identify design factors that make the analyzed tapers susceptible to wear and corrosion. A quantitative analysis of wear from circular and flat taper designs for a mixed metal coupling (CoCr-TMZF) was performed. Based on the reconstruction of explanted taper geometries, individual engagement properties are determined, providing an estimate of the contact situation at the taper interface in-vivo. This mechanical approach gave explanations of the arrangement of local wear phenomena at the taper interface.Publicationtype: Doctoral Thesis718 490 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Primary hip replacement stem taper fracture due to corrosion in 3 patients(Taylor & Francis, 2016-11-06); ; ; ; Publicationtype: Journal ArticleScopus© Citations 14 269 438 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Quantification of material loss from the neck piece taper junctions of a bimodular primary hip prosthesis. A retrieval study from 27 failed Rejuvenate bimodular hip arthroplasties(2015-10); ; ; The early failure and revision of bimodular primary total hip arthroplasty prostheses requires the identification of the risk factors for material loss and wear at the taper junctions through taper wear analysis. Deviations in taper geometries between revised and pristine modular neck tapers were determined using high resolution tactile measurements. A new algorithm was developed and validated to allow the quantitative analysis of material loss, complementing the standard visual inspection currently used. The algorithm was applied to a sample of 27 retrievals (in situ from 2.9 to 38.1 months) of the withdrawn Rejuvenate modular prosthesis. The mean wear volumes on the flat distal neck piece taper was 3.35 mm(3) (0.55 to 7.57), mainly occurring in a characteristic pattern in areas with high mechanical loading. Wear volume tended to increase with time to revision (r² = 0.423, p = 0.001). Implant and patient specific data (offset, stem size, patient's mass, age and body mass index) did not correlate with the amount of material loss observed (p > 0.078). Bilaterally revised implants showed higher amounts of combined total material loss and similar wear patterns on both sides. The consistent wear pattern found in this study has not been reported previously, suggesting that the device design and materials are associated with the failure of this prosthesis.Publicationtype: Journal Article130