This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection. A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years’ clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery.Aims
Methods
Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors. Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti12Mo6Zr2Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients.Aims
Methods
This study compared the cobalt and chromium serum ion concentration of patients treated with two different metal-on-metal (MoM) hinged total knee arthroplasty (TKA) systems, as well as a titanium nitride (TiN)-coated variant. A total of 63 patients (65 implants) were treated using either a MoM-coated (n = 29) or TiN-coated (n = 7) hinged TKA (GenuX mobile bearing, MUTARS; Implantcast, Germany) versus the BPKS (Brehm, Germany) hinged TKA (n = 27), in which the weight placed on the MoM hinge is diffused through a polyethylene (PE) inlay, reducing the direct load on the MoM hinge. Serum cobalt and chromium ion concentrations were assessed after minimum follow-up of 12 months, as well as functional outcome and quality of life.Aims
Methods
Large-diameter metal-on-metal (MoM) total hip arthroplasty (THA) has demonstrated unexpected high failure rates and pseudotumour formation. The purpose of this prospective cohort study is to report ten-year results in order to establish revision rate, prevalence of pseudotumour formation, and relation with whole blood cobalt levels. All patients were recalled according to the guidelines of the Dutch Orthopaedic Association. They underwent clinical and radiographical assessments (radiograph and CT scan) of the hip prosthesis and whole blood cobalt ion measurements. Overall, 94 patients (95 hips) fulfilled our requirements for a minimum ten-year follow-up.Aims
Methods
The present study investigated the five-year interval changes in pseudotumours and measured serum metal ions at long-term follow-up of a previous report of 28 mm diameter metal-on-metal (MoM) total hip arthroplasty (THA). A total of 72 patients (mean age 46.6 years (37 to 55); 43 men, 29 women; 91 hips) who underwent cementless primary MoM THA with a 28 mm modular head were included. The mean follow-up duration was 20.3 years (18 to 24). All patients had CT scans at a mean 15.1 years (13 to 19) after the index operation and subsequent follow-up at a mean of 20.2 years (18 to 24). Pseudotumour volume, type of mass, and new-onset pseudotumours were evaluated using CT scanning. Clinical outcomes were assessed by Harris Hip Score (HHS) and the presence of groin pain. Serum metal ion (cobalt (Co) and chromium (Cr)) levels were measured at the latest follow-up.Aims
Patients and Methods
The leading indication for revision total hip
arthroplasty (THA) remains aseptic loosening owing to wear. The younger,
more active patients currently undergoing THA present unprecedented
demands on the bearings. Ceramic-on-ceramic (CoC) bearings have
consistently shown the lowest rates of wear. The recent advances,
especially involving alumina/zirconia composite ceramic, have led
to substantial improvements and good results Alumina/zirconia composite ceramics are extremely hard, scratch
resistant and biocompatible. They offer a low co-efficient of friction
and superior lubrication and lower rates of wear compared with other
bearings. The major disadvantage is the risk of fracture of the
ceramic. The new composite ceramic has reduced the risk of fracture
of the femoral head to 0.002%. The risk of fracture of the liner
is slightly higher (0.02%). Assuming that the components are introduced without impingement,
CoC bearings have major advantages over other bearings. Owing to
the superior hardness, they produce less third body wear and are
less vulnerable to intra-operative damage. The improved tribology means that CoC bearings are an excellent
choice for young, active patients requiring THA. Cite this article:
We investigated the changes seen on serial metal
artefact reduction magnetic resonance imaging scans (MARS-MRI) of
metal-on-metal total hip arthroplasties (MoM THAs). In total 155
THAs, in 35 male and 100 female patients (mean age 70.4 years, 42
to 91), underwent at least two MRI scans at a mean interval of 14.6
months (2.6 to 57.1), at a mean of 48.2 months (3.5 to 93.3) after
primary hip surgery. Scans were graded using a modification of the
Oxford classification. Progression of disease was defined as an
increase in grade or a minimum 10% increase in fluid lesion volume
at second scan. A total of 16 hips (30%) initially classified as
‘normal’ developed an abnormality on the second scan. Of those with
‘isolated trochanteric fluid’ 9 (47%) underwent disease progression,
as did 7 (58%) of ‘effusions’. A total of 54 (77%) of hips initially
classified as showing adverse reactions to metal debris (ARMD) progressed,
with higher rates of progression in higher grades. Disease progression
was associated with high blood cobalt levels or an irregular pseudocapsule
lining at the initial scan. There was no association with changes
in functional scores. Adverse reactions to metal debris in MoM THAs
may not be as benign as previous reports have suggested. Close radiological
follow-up is recommended, particularly in high-risk groups. Cite this article:
We conducted a retrospective study to assess
the prevalence of adverse reactions to metal debris (ARMD) in patients
operated on at our institution with metal-on-metal (MoM) total hip
replacements with 36 mm heads using a Pinnacle acetabular shell.
A total of 326 patients (150 males, 175 hips; 176 females, 203 hips)
with a mean age of 62.7 years (28 to 85) and mean follow-up of 7.5
years (0.1 to 10.8) participating in our in-depth modern MoM follow-up
programme were included in the study, which involved recording whole
blood cobalt and chromium ion measurements, Oxford hip scores (OHS)
and plain radiographs of the hip and targeted cross-sectional imaging. Elevated
blood metal ion levels (>
5 parts per billion) were seen in 32 (16.1%)
of the 199 patients who underwent unilateral replacement. At 23
months after the start of our modern MoM follow-up programme, 29
new cases of ARMD had been revealed. Hence, the nine-year survival
of this cohort declined from 96% (95% CI 95 to 98) with the old
surveillance routine to 86% (95% CI 82 to 90) following the new
protocol. Although ARMD may not be as common in 36 mm MoM THRs as
in those with larger heads, these results support the Medicines
and Healthcare Products Regulatory Agency guidelines on regular
reviews and further investigations, and emphasise the need for specific
a follow-up programme for patients with MoM THRs. Cite this article:
The August 2014 Hip &
Pelvis Roundup360 looks at: Serial MRIs best for pseudotumour surveillance; Is ultrasound good enough for MOM follow-up?; Does weight loss in obese patients help?; Measuring acetabular anteversion on plain films; Two-stage one-stage too many in fungal hip revisions? and 35 is the magic number in arthroplasty.
The February 2014 Hip &
Pelvis Roundup360 looks at: length of stay; cementless metaphyseal fixation; mortality trends in over 400,000 total hip replacements; antibiotics in hip fracture surgery; blood supply to the femoral head after dislocation; resurfacing and THR in metal-on-metal replacement; diabetes and hip replacement; bone remodelling over two decades following hip replacement; and whether bisphosphonates affect acetabular fixation.
The aim of this study was to establish the natural
course of unrevised asymptomatic pseudotumours after metal-on-metal
(MoM) hip resurfacing during a six- to 12-month follow-up period.
We used repeated metal artefact reduction sequence (MARS)-magnetic
resonance imaging (MRI), serum metal ion analysis and clinical examination to
study 14 unrevised hips (mean patient age 52.7 years, 46 to 68,
5 female, 7 male) with a pseudotumour and 23 hips (mean patient
age 52.8 years, 38 to 69, 7 female, 16 male) without a pseudotumour.
The mean post-operative time to the first MARS-MRI scan was 4.3 years
(2.2 to 8.3), and mean time between the first and second MARS-MRI scan
was eight months (6 to 12). At the second MRI scan, the grade of
severity of the pseudotumour had not changed in 35 hips. One new
pseudotumour (Anderson C2 score, moderate) was observed, and one
pseudotumour was downgraded from C2 (moderate) to C1 (mild). In
general, the characteristics of the pseudotumours hardly changed. Repeated MARS-MRI scans within one year in patients with asymptomatic
pseudotumours after MoM hip resurfacing showed little or no variation.
In 23 patients without pseudotumour, one new asymptomatic pseudotumour
was detected. This is the first longitudinal study on the natural history of
pseudotumours using MARS-MRI scans in hip resurfacing, and mirrors
recent results for 28 mm diameter MoM total hip replacement. Cite this article:
Objectives.
We present the clinical results and survivorship
of consecutive 100 Birmingham Hip Resurfacings in 90 patients at
a minimum follow-up of ten years. All procedures were carried out
by an independent surgeon who commenced a prospective study in 1998.
Patients were assessed clinically using the Western Ontario and
McMaster Universities osteoarthritis index, Short-Form 36, Harris
hip score and University of California, Los Angeles activity score. Radiological
analysis was performed by an independent observer and blood metal
ion levels concentrations were measured at ten years post-operatively
in 62 patients. The median acetabular component inclination was
46.2° (34° to 59°) and anteversion 11.0° (0° to 30°). The median
chromium concentration in the unilateral group was 1.74 (0.41 to
15.23) and for the bilateral group was 2.98 (1.57 to 18.01). The
equivalent values for cobalt were 1.67 (0.54 to 20.4) and 1.88 (1.38
to 19.32). In total there were eight failures giving an overall survival
at ten years of 92% (95% confidence interval (CI) 86.7 to 97.3).
BHR in male patients had an improved survivorship of 94.6% (95%
CI 89.4 to 100) compared with females at 84.6% (95% CI 70.7 to 98.5),
but this did not reach statistical significance (p = 0.119). Four
of the nine BHRs with a bearing diameter of 42 mm failed. The overall results were consistent with data produced from other
centres in that the clinical outcome of large male patients was
extremely encouraging, whereas the survival of the smaller joints
was less satisfactory.
Metal-on-metal (MoM) hip resurfacing was introduced into clinical
practice because it was perceived to be a better alternative to
conventional total hip replacement for young and active patients.
However, an increasing number of reports of complications have arisen
focusing on design and orientation of the components, the generation
of metallic wear particles and serum levels of metallic ions. The
procedure introduced a combination of two elements: large-dimension
components and hard abrasive particles of metal wear. The objective
of our study was to investigate the theory that microseparation
of the articular surfaces draws in a high volume of bursal fluid
and its contents into the articulation, and at relocation under
load would generate high pressures of fluid ejection, resulting
in an abrasive water jet. This theoretical concept using MoM resurfacing components (head
diameter 55 mm) was modelled mathematically and confirmed experimentally
using a material-testing machine that pushed the head into the cup
at a rate of 1000 mm/min until fully engaged.Objectives
Methods
We report a case of a male patient presenting
with bilateral painful but apparently well-positioned and -fixed
large-diameter metal-on-metal hip replacements four years post-operatively.
Multiple imaging modes revealed a thick-walled, cystic expansile
mass in communication with the hip joint (a pseudotumour). Implant
retrieval analysis and tissue culture eliminated high bearing wear
or infection as causes for the soft-tissue reaction, but noted marked corrosion
of the modular neck taper adaptor and corrosion products in the
tissues. Therefore, we believe corrosion products from the taper
caused by mismatch of the implant components led to pseudotumour
formation requiring revision.
Lately, concerns have arisen following the use of large metal-on-metal bearings in hip replacements owing to reports of catastrophic soft-tissue reactions resulting in implant failure and associated complications. This review examines the literature and contemporary presentations on current clinical dilemmas in metal-on-metal hip replacement.
We review the history and literature of hip resurfacing arthroplasty. Resurfacing and the science behind it continues to evolve. Recent results, particularly from the national arthroplasty registers, have spread disquiet among both surgeons and patients. A hip resurfacing arthroplasty is not a total hip replacement, but should perhaps be seen as a means of delaying it. The time when hip resurfacing is offered to a patient may be different from that for a total hip replacement. The same logic can apply to the timing of revision surgery. Consequently, the comparison of resurfacing with total hip replacement may be a false one. Nevertheless, the need for innovative solutions for young arthroplasty patients is clear. Total hip replacement can be usefully delayed in many of these patients by the use of hip resurfacing arthroplasty.
Pseudotumour is a rare but important complication of metal-on-metal hip resurfacing that occurs much more commonly in women than in men. We examined the relationship between head-neck ratio (HNR) and pseudotumour formation in 18 resurfaced hips (18 patients) revised for pseudotumour and 42 asymptomatic control resurfaced hips (42 patients). Patients in whom pseudotumour formation had occurred had higher pre-operative HNR than the control patients (mean 1.37 ( We suggest that reducing the size of the femoral head, made possible by a high pre-operative HNR, increases the risk of impingement and edge loading, and may contribute to high wear and pseudotumour formation. As the incidence of pseudotumour is low in men, it appears safe to perform resurfacing in men. However, this study suggests that it is also reasonable to resurface in women with a pre-operative HNR ≤ 1.3.
The presence of pseudotumours, which are soft-tissue masses relating to the hip, after metal-on-metal hip resurfacing arthroplasty has been associated with elevated levels of metal ions in serum, suggesting that pseudotumours occur when there is increased wear. We aimed to quantify the wear in vivo of implants revised for pseudotumours (eight) and of a control group of implants (22) revised for other reasons of failure. We found that the implant group with pseudotumours had a significantly higher rate of median linear wear of the femoral component at 8.1 μm/year (2.75 to 25.4) than the 1.79 μm/year (0.82 to 4.15; p = 0.002) of the non-pseudotumour group. For the acetabular component a significantly higher rate of median linear wear of 7.36 μm/year (1.61 to 24.9) was observed in the pseudotumour group compared with 1.28 μm/year (0.81 to 3.33, p = 0.001) in the other group. Wear of the acetabular component in the pseudotumour group always involved the edge of the implant, indicating that edge-loading had occurred. Our findings are the first direct evidence that pseudotumour is associated with increased wear at the metal-on-metal articulation. Furthermore, edge-loading with the loss of fluid-film lubrication may be an important mechanism of generation of wear in patients with a pseudotumour.