Aims

In metal-on-polyethylene (MoP) total hip arthroplasty (THA), large metal femoral heads have been used to increase stability and reduce the risk of dislocation. The increased size of the femoral head can, however, lead to increased taper corrosion, with the release of metal ions and adverse reactions. The aim of this study was to investigate the relationship between the size of the femoral head and the levels of metal ions in the blood in these patients.

Aims

The risk of mechanical failure of modular revision hip stems is frequently mentioned in the literature, but little is currently known about the actual clinical failure rates of this type of prosthesis. The current retrospective long-term analysis examines the distal and modular failure patterns of the Prevision hip stem from 18 years of clinical use. A design improvement of the modular taper was introduced in 2008, and the data could also be used to compare the original and the current design of the modular connection.

Reducing wear of endoprosthetic implants is still an important goal in order to increase the life time of the implant. Endoprosthesis failure can be caused by many different mechanisms, such as abrasive wear, corrosion, fretting or foreign body reactions due to wear accumulation. Especially, modular junctions exhibit high wear rates and corrosion due to micromotions at the connection of the individual components. The wear generation of cobalt-chromium-molybdenum alloys (CoCrMo) is strongly influenced by the microstructure. Therefore, the aim of this work is to investigate the subsurface phase transformation by deep rolling manufacturing processes in combination with a “sub-zero” cooling strategy. We analyzed the influence on the phase structure and the mechanical properties of wrought CoCr28Mo6 alloy (ISO 5832-12) by a deep rolling manufacturing process at various temperatures (+25°C,-10°C,-35°C) and different normal forces (700N and 1400N). Surface (S. a. ,S. z. ) and subsurface characteristics (residual stress) as well as biological behavior were investigated for a potential implant application. We showed that the microstructure of CoCr28Mo6 wrought alloy changes depending on applied force and temperature. The face centered cubic (fcc) phase could be transformed to a harder hexagonal-close-packed (hcp) phase structure in the subsurface. The surface could be smoothed (up to S. a. = 0.387 µm±0.185 µm) and hardened (≥ 700 HV 0.1) at the same time. The residual stress was increased by more than 600% (n=3). As a readout for metabolic activity of MonoMac (MM6) and osteosarcoma (SaOS-2) cells a WST assay (n=3) was used. The cells showed no significant negative effect of the sub-zero manufacturing process. We showed that deep rolling in combination with an innovative cooling strategy for the manufacturing process has a great potential to improve the mechanical properties of CoCr28Mo6 wrought alloy, by subsurface hardening and phase transformation for implant applications

Aims

Taper corrosion has been widely reported to be problematic for modular total hip arthroplasty implants. A simple and systematic method to evaluate taper damage with sufficient resolution is needed. We introduce a semiquantitative grading system for modular femoral tapers to characterize taper corrosion damage.

Aims

The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes.

Modular femoral stems offer surgeons great flexibility in biomechanical configuration during total hip replacement (THR) however introduce a taper-trunnion articulation known to be a source of additional wear debris through crevice, fretting and galvanic corrosion with mixed material combinations. This study aimed to investigate the influence of the trunnion bearing surface combination on the revision rate following primary total hip replacement (THR). All patients who underwent THR using an Exeter V40 cemented stainless steel stem and monobloc cemented polyethylene acetabular component (uncemented cups excluded to standardise the acetabular bearing surface and fixation) between January 2003 and December 2019 were extracted from the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man. The primary exposure was the head substrate used corresponding to the trunnion bearing. Time-to-event was determined by duration of implantation from primary surgery to revision with cases censored at death or end of available follow-up. Multivariable Cox proportional hazard models were used to identify predictors of all cause revision, adjusted for age, sex, American Association of Anaesthesiologists (ASA) grade, body mass index, surgical indication (osteoarthritis or other), and femoral head size. 229,870 THR were identified (66% female, mean age 73.4 years (SD 9.1) with the majority (91%) performed for osteoarthritis of which 4,598 were revised. Mean time from primary to revision or censoring was 6.8 years (SD 4.0). Multivariable modelling showed CoCr/SS trunnions were associated with a significantly higher risk of revision (hazard ratio (HR) 1.31 (95%CI 1.15 to 1.48, p<0.0001) as compared to SS/SS (reference). Both Alumina/SS (HR 0.74 (0.65 to 0.84), p<0.0001) and Zirconia/SS (HR 0.61 (0.49 to 0.74), p<0.0001) were associated with a significantly lower risk of revision. Ceramic heads on an Exeter stem were associated with significantly improved survivorship compared to metal heads in primary THR. CoCr/SS trunnion articulations had the poorest survivorship which may be contributed to by trunnionosis

Aims

A recent report from France suggested an association between the use of cobalt-chrome (CoCr) femoral heads in total hip arthroplasties (THAs) and an increased risk of dilated cardiomyopathy and heart failure. CoCr is a commonly used material in orthopaedic implants. If the reported association is causal, the consequences would be significant given the millions of joint arthroplasties and other orthopaedic procedures in which CoCr is used annually. We examined whether CoCr-containing THAs were associated with an increased risk of all-cause mortality, heart outcomes, cancer, and neurodegenerative disorders in a large national database.

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This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.

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Prior studies have identified that malseating of a modular dual mobility liner can occur, with previous reported incidences between 5.8% and 16.4%. The aim of this study was to determine the incidence of malseating in dual mobility implants at our institution, assess for risk factors for liner malseating, and investigate whether liner malseating has any impact on clinical outcomes after surgery.

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The aim of this study was to present the first retrieval analysis findings of PRECICE STRYDE intermedullary nails removed from patients, providing useful information in the post-market surveillance of these recently introduced devices.

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This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported.

Aims. Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice corrosion at the modular liner-shell connection. We sought to examine fretting and corrosion on MDM liners, to analyze the corrosion products, and to examine histologically the periprosthetic tissues. Methods. A total of 60 retrieved liners were subjectively scored for fretting and corrosion. The corrosion products from the three most severely corroded implants were removed from the implant surface, imaged using scanning electron microscopy, and analyzed using Fourier-transform infrared spectroscopy. Results. Fretting was present on 88% (53/60) of the retrieved liners, and corrosion was present on 97% (58/60). Fretting was most often found on the lip of the taper at the transition between the lip and the dome regions. Macrophages and particles reflecting an innate inflammatory reaction to corrosion debris were noted in six of the 48 cases for which periprosthetic tissues were examined, and all were associated with retrieved components that had high corrosion scores. Conclusion. Our results show that corrosion occurs at the interface between MDM liners and shells and that it can be associated with reactions in the local tissues, suggesting continued concern that this problem may become clinically important with longer-term use of these implants. Cite this article: Bone Joint J 2021;103-B(7):1238–1246

Aims

Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years.

Abstract. Objectives. Modular dual-mobility (MDM) constructs are used to reduce dislocation rates after total hip replacement (THR). They combine the advantages of dual mobility with the option of supplementary acetabular screw fixation in complex revision surgery. However, there are concerns about adverse reaction to metal debris (ARMD) as a result of fretting corrosion between the metal liner and shell. Methods. The aim of this systematic review was to find and review all relevant studies to establish the outcomes and risks associated with MDM hip replacement. All articles on MDM THRs in the Medline, EMBASE, CINAHL, Cochrane Library, and Prospero databases were searched. A total of 14 articles were included. A random intercept logistic regression model was used for meta-analysis, giving estimated mean values. Results. There were 6 cases of ARMD out of 1312 total. Estimated median incidence of ARMD from meta-analysis was 0.3% (95% CI 0.1 – 1.4%). Mean postoperative serum Cobalt was 0.81 μg/L (95% CI 0.33 – 1.29 μg/L), and Chromium was 0.77 μg/L (95% 0.35 – 1.19 μg/L), from 279 cases in 7 studies. Estimated median incidence of a serum cobalt or chromium ion measurement ≥1 μg/L was 7.9% (95% CI 3.5 – 16.8%), and ≥7 μg/L was 1.8% (95% CI 0.7 – 4.2%). Conclusions. ARMD is a rare but significant complication following total hip replacement using a MDM construct. Its incidence appears higher than that reported in non-metal-on-metal (MoM) hip replacements but lower than that of MoM hip replacements. MDM hip replacements are associated with raised serum metal ion levels postoperatively, but there was no correlation with worse clinical hip function within studies. Studies were poor quality and at high risk of confounding. Pending further work, MDM constructs should be used with caution, reserved for select cases at particularly high risk of dislocation. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Taper corrosion and fretting have been associated with oxide layer abrasion and fluid ingress that contributes to adverse local tissue reactions with potential failure of the hip joint replacement. [1,2]. Both mechanisms are considered to be affected by the precise nature of the taper design. [3]. Indeed relative motion at the taper interface that causes fretting damage and wear effects, such as pistoning and rocking, have been described following analysis of implants at retrieval. [4,5]. However, there is much less reported about the mechanisms that allow the fluid ingress/egress at the taper interface which would drive corrosion. Thus the aim of the present study was to investigate the effect of trunnion design on the gap opening and taper relative motions under different load scenarios and taper designs. A 3-D finite element model of a 40mm CoCr modular femoral head and a Ti6Al4V trunnion was established in Abaqus CAE/2018. Femoral head and trunnion geometries were meshed with an element (C3D8) size of 0.17mm. Tapers were assembled by simulating a range of impact forces (AF); taper interface behaviour was evaluated under physiological forces and frictional moments simulated during walking activity. [6]. , assuming different coefficients of friction (CF), Figure 1. The output involved the total and normal relative motion of the surfaces at the taper interface. The model predicted for a taper mismatch of 0.36° which, when combined with an assembly force of 2kN, generated the largest taper gap opening (59.2mm) during walking, Figure 2. In all trunnion designs the largest normal relative motion coincided with heel strike in the gait cycle (0–5%). The taper gap and normal relative motions were related to the initial taper lock area. Furthermore, the direction of the total motion was different in all three taper mismatches, with a shift in the direction towards the normal of the surface as the taper mismatch increased, Figure 3. By contrast, the direction of the normal relative motions did not change with different trunnion designs. Contact patterns were asymmetrical and contact areas varied throughout the walking activity; contact pressure and the largest taper gap were located on the same side of the taper, suggesting toggling of the trunnion. The relationship between taper gap opening and initial taper lock contact area suggests that the taper contact area functions as a fulcrum in a lever mechanism. Large taper mismatches create larger relative motions that will not only create more wear and fretting damage but also larger normal relative motions. This may allow fluid ingress into the taper interface and/or the egress of fluid along with any metal wear particles into the body. This increased understanding of the taper motion will result in improved designs and ultimately taper performance. For any figures or tables, please contact the authors directly

Objectives. Modular dual-mobility (MDM) constructs are used to reduce dislocation rates after total hip replacement (THR). They combine the advantages of dual mobility with the option of supplementary acetabular screw fixation in complex revision surgery. However, there are concerns about adverse reaction to metal debris (ARMD) as a result of fretting corrosion between the metal liner and shell. Methods: The aim of this systematic review was to find and review all relevant studies to establish the outcomes and risks associated with MDM hip replacement. All articles on MDM THRs in the Medline, EMBASE, CINAHL, Cochrane Library, and Prospero databases were searched. A total of 14 articles were included. A random intercept logistic regression model was used for meta-analysis, giving estimated average values. Results: There were 6 cases of ARMD out of 1312 total. Estimated median incidence of ARMD from meta-analysis was 0.3% (95% CI 0.1 – 1.4%). Mean postoperative serum Cobalt was 0.81 μg/L (95% CI 0.33 – 1.29 μg/L), and Chromium was 0.77 μg/L (95% 0.35 – 1.19 μg/L), from 279 cases in 7 studies. Estimated median incidence of a serum cobalt or chromium ion measurement ≥1 μg/L was 7.9% (95% CI 3.5 – 16.8%), and ≥7 μg/L was 1.8% (95% CI 0.7 – 4.2%). Conclusions: ARMD is a rare but significant complication following total hip replacement using a MDM construct. Its incidence appears higher than that reported in non-metal-on-metal (MoM) hip replacements but lower than that of MoM hip replacements. MDM hip replacements are associated with raised serum metal ion levels postoperatively, but there was no correlation with worse clinical hip function within studies. Studies were poor quality and at high risk of confounding. Pending further work, MDM constructs should be used with caution, reserved for select cases at particularly high risk of dislocation

Aims

The Exeter V40 cemented femoral stem was first introduced in 2000. The largest single-centre analysis of this implant to date was published in 2018 by Westerman et al. Excellent results were reported at a minimum of ten years for the first 540 cases performed at the designer centre in the Exeter NHS Trust, with stem survivorship of 96.8%. The aim of this current study is to report long-term outcomes and survivorship for the Exeter V40 stem in a non-designer centre.