We investigated the reliability of the cobalt-chromium (CoCr) synovial joint fluid ratio (JFR) in identifying the presence of a severe aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) response and/or suboptimal taper performance (SOTP) following metal-on-metal (MoM) hip arthroplasty. We then examined the possibility that the CoCr JFR may influence the serum partitioning of Co and Cr. For part A, we included all revision surgeries carried out at our unit with the relevant data, including volumetric wear analysis, joint fluid (JF) Co and Cr concentrations, and ALVAL grade (n = 315). Receiver operating characteristic curves were constructed to assess the reliability of the CoCr JFR in identifying severe ALVAL and/or SOTP. For part B, we included only patients with unilateral prostheses who had given matched serum and whole blood samples for Co and Cr analysis (n = 155). Multiple regression was used to examine the influence of JF concentrations on the serum partitioning of Co and Cr in the blood.Objectives
Methods
Our first aim was to determine whether there are significant
changes in the level of metal ions in the blood at mid-term follow-up,
in patients with an Articular Surface Replacement (ASR) arthroplasty.
Secondly, we sought to identify risk factors for any increases. The study involved 435 patients who underwent unilateral, metal-on-metal
(MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). These
patients all had one measurement of the level of metal ions in the
blood before seven years had passed post-operatively (early evaluation)
and one after seven years had passed post-operatively (mid-term evaluation).
Changes in ion levels were tested using a Wilcoxon signed-rank test.
We identified subgroups at the highest risk of increase using a
multivariable linear logistic regression model.Aims
Patients and Methods
Early failure associated with adverse reactions to metal debris is an emerging problem after hip resurfacing but the exact mechanism is unclear. We analysed our entire series of 660 metal-on-metal resurfacings (Articular Surface Replacement (ASR) and Birmingham Hip Resurfacing (BHR)) and large-bearing ASR total hip replacements, to establish associations with metal debris-related failures. Clinical and radiological outcomes, metal ion levels, explant studies and lymphocyte transformation tests were performed. A total of 17 patients (3.4%) were identified (all ASR bearings) with adverse reactions to metal debris, for which revision was required. This group had significantly smaller components, significantly higher acetabular component anteversion, and significantly higher whole concentrations of blood and joint chromium and cobalt ions than asymptomatic patients did (all p <
0.001). Post-revision lymphocyte transformation tests on this group showed no reactivity to chromium or cobalt ions. Explants from these revisions had greater surface wear than retrievals for uncomplicated fractures. The absence of adverse reactions to metal debris in patients with well-positioned implants usually implies high component wear. Surgeons must consider implant design, expected component size and acetabular component positioning in order to reduce early failures when performing large-bearing metal-on-metal hip resurfacing and replacement.
There are many guidelines that help direct the management of
patients with metal-on-metal (MOM) hip arthroplasties. We have undertaken
a study to compare the management of patients with MOM hip arthroplasties in
different countries. Six international tertiary referral orthopaedic centres were
invited to participate by organising a multi-disciplinary team (MDT)
meeting, consisting of two or more revision hip arthroplasty surgeons
and a musculoskeletal radiologist. A full clinical dataset including
history, blood tests and imaging for ten patients was sent to each
unit, for discussion and treatment planning. Differences in the
interpretation of findings, management decisions and rationale for
decisions were compared using quantitative and qualitative methods.Aims
Methods
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.
The aim of this study was to determine whether the rates of revision
for metal-on-metal (MoM) total hip arthroplasties (THAs) with Pinnacle
components varied according to the year of the initial operation,
and compare these with the rates of revision for other designs of
MoM THA. Data from the National Joint Registry for England and Wales included
36 mm MoM THAs with Pinnacle acetabular components which were undertaken
between 2003 and 2012 with follow-up for at least five years (n
= 10 776) and a control group of other MoM THAs (n = 13 817). The
effect of the year of the primary operation on all-cause rates of revision
was assessed using Cox regression and interrupted time-series analysis.Aims
Patients and Methods
We undertook a retrospective cohort study to
determine clinical outcomes following the revision of metal-on-metal (MoM)
hip replacements for adverse reaction to metal debris (ARMD), and
to identify predictors of time to revision and outcomes following
revision. Between 1998 and 2012 a total of 64 MoM hips (mean age
at revision of 57.8 years; 46 (72%) female; 46 (72%) hip resurfacings
and 18 (28%) total hip replacements) were revised for ARMD at one specialist
centre. At a mean follow-up of 4.5 years (1.0 to 14.6) from revision
for ARMD there were 13 hips (20.3%) with post-operative complications
and eight (12.5%) requiring re-revision. The Kaplan–Meier five-year survival rate for ARMD revision was
87.9% (95% confidence interval 78.9 to 98.0; 19 hips at risk). Excluding
re-revisions, the median absolute Oxford hip score (OHS) following
ARMD revision using the percentage method (0% best outcome and 100%
worst outcome) was 18.8% (interquartile range (IQR) 7.8% to 48.3%),
which is equivalent to 39/48 (IQR 24.8/48 to 44.3/48) when using
the modified OHS. Histopathological response did not affect time
to revision for ARMD (p = 0.334) or the subsequent risk of re-revision
(p = 0.879). Similarly, the presence or absence of a contralateral
MoM hip bearing did not affect time to revision for ARMD (p = 0.066)
or the subsequent risk of re-revision (p = 0.178). Patients revised to MoM bearings had higher rates of re-revision
(five of 16 MoM hips re-revised; p = 0.046), but those not requiring
re-revision had good functional results (median absolute OHS 14.6%
or 41.0/48). Short-term morbidity following revision for ARMD was
comparable with previous reports. Caution should be exercised when choosing
bearing surfaces for ARMD revisions. 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:
The long term biological effects of wear products
following total hip arthroplasty (THA) are unclear. However, the indications
for THA are expanding, with increasingly younger patients undergoing
the procedure. This prospective, randomised study compared two groups of patients
undergoing THA after being randomised to receive one of two different
bearing surfaces: metal-on-polyethylene (MoP) n = 22 and metal-on-metal
(MoM) n = 23. We investigated the relationship between three variables:
bearing surface (MoP Our results demonstrated significantly higher mean cobalt and
chromium (Co and Cr) blood levels in the MoM group at all follow-up
points following surgery (p <
0.01), but there were no significant
differences in the chromosomal aberration indices between MoM and
MoP at two or five years (two years: p = 0.56, p = 0.08, p = 0.91, p
= 0.51 and five years: p = 0.086, p = 0.73, p = 0.06, p = 0.34)
for translocations, breaks, loss and gain of chromosomes respectively.
Regression analysis showed a strong linear relationship between
Cr levels and the total chromosomal aberration indices in the MoM
group (R2 = 0.90016), but this was not as strong for
Co (R2 = 0.68991). In the MoP group, the analysis revealed
a poor relationship between Cr levels and the total chromosomal
aberration indices (R2 = 0.23908) but a slightly stronger
relationship for Co (R2 = 0.64292). Across both groups,
Spearman’s correlation detected no overall association between Co and Cr
levels and each of the studied chromosomal aberrations. There remains
no clear indication which THA bearing couple is the most biocompatible,
especially in young active patients. While THA continues to be very
successful at alleviating pain and restoring function, the long-term
biological implications of the procedure still require further scrutiny. Cite this article:
Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA)
are commonly used, but concerns exist regarding ceramic fracture.
This study aims to report the risk of revision for fracture of modern
CoC bearings and identify factors that might influence this risk,
using data from the National Joint Registry (NJR) for England, Wales, Northern
Ireland and the Isle of Man. We analysed data on 223 362 bearings from 111 681 primary CoC
THAs and 182 linked revisions for bearing fracture recorded in the
NJR. We used implant codes to identify ceramic bearing composition
and generated Kaplan-Meier estimates for implant survivorship. Logistic
regression analyses were performed for implant size and patient specific
variables to determine any associated risks for revision.Aims
Patients and Methods
Ceramic-on-metal (CoM) is a relatively new bearing
combination for total hip arthroplasty (THA) with few reported outcomes.
A total of 287 CoM THAs were carried out in 271 patients (mean age
55.6 years (20 to 77), 150 THAs in female patients, 137 in male)
under the care of a single surgeon between October 2007 and October
2009. With the issues surrounding metal-on-metal bearings the decision
was taken to review these patients between March and November 2011,
at a mean follow-up of 34 months (23 to 45) and to record pain,
outcome scores, radiological analysis and blood ion levels. The
mean Oxford Hip Score was 19.2 (12 to 53), 254 patients with 268
hips (95%) had mild/very mild/no pain, the mean angle of inclination
of the acetabular component was 44.8o (28o to
63o), 82 stems (29%) had evidence of radiolucent lines
of >
1 mm in at least one Gruen zone and the median levels of cobalt
and chromium ions in the blood were 0.83 μg/L (0.24 μg/L to 27.56 μg/L)
and 0.78 μg/L (0.21 μg/L to 8.84 μg/L), respectively. The five-year
survival rate is 96.9% (95% confidence interval 94.7% to 99%). Due to the presence of radiolucent lines and the higher than
expected levels of metal ions in the blood, we would not recommend
the use of CoM THA without further long-term follow-up. We plan
to monitor all these patients regularly. Cite this article:
We wished to investigate the influence of metal debris exposure
on the subsequent immune response and resulting soft-tissue injury
following metal-on-metal (MoM) hip arthroplasty. Some reports have
suggested that debris generated from the head-neck taper junction
is more destructive than equivalent doses from metal bearing surfaces. We investigated the influence of the source and volume of metal
debris on chromium (Cr) and cobalt (Co) concentrations in corresponding
blood and hip synovial fluid samples and the observed agglomerated
particle sizes in excised tissues using multiple regression analysis
of prospectively collected data. A total of 199 explanted MoM hips
(177 patients; 132 hips female) were analysed to determine rates
of volumetric wear at the bearing surfaces and taper junctions. Aims
Patients and Methods
The use of ceramic femoral heads in total hip arthroplasty (THA) has increased due to their proven low bearing wear characteristics. Ceramic femoral heads are also thought to reduce wear and corrosion at the head-stem junction with titanium (Ti) stems when compared with metal heads. We sought to evaluate taper damage of ceramic compared with metal heads when paired with cobalt chromium (CoCr) alloy stems in a single stem design. This retrieval study involved 48 total hip arthroplasties (THAs) with CoCr V40 trunnions paired with either CoCr (n = 21) or ceramic (n = 27) heads. The taper junction of all hips was evaluated for fretting/corrosion damage and volumetric material loss using a roundness-measuring machine. We used linear regression analysis to investigate taper damage differences after adjusting for potential confounding variables.Objectives
Methods
To determine the outcomes following revision surgery of metal-on-metal
hip arthroplasties (MoMHA) performed for adverse reactions to metal
debris (ARMD), and to identify factors predictive of re-revision. We performed a retrospective observational study using National
Joint Registry (NJR) data on 2535 MoMHAs undergoing revision surgery
for ARMD between 2008 and 2014. The outcomes studied following revision were
intra-operative complications, mortality and re-revision surgery.
Predictors of re-revision were identified using competing-risk regression
modelling.Aims
Patients and Methods
Plasma levels of cobalt and chromium ions and
Metal Artefact Reduction Sequence (MARS)-MRI scans were performed
on patients with 209 consecutive, unilateral, symptomatic metal-on-metal
(MoM) hip arthroplasties. There was wide variation in plasma cobalt
and chromium levels, and MARS-MRI scans were positive for adverse reaction
to metal debris (ARMD) in 84 hips (40%). There was a significant
difference in the median plasma cobalt and chromium levels between
those with positive and negative MARS-MRI scans (p <
0.001).
Compared with MARS-MRI as the potential reference standard for the
diagnosis of ARMD, the sensitivity of metal ion analysis for cobalt
or chromium with a cut-off of >
7 µg/l was 57%. The specificity was
65%, positive predictive value was 52% and the negative predictive
value was 69% in symptomatic patients. A lowered threshold of >
3.5 µg/l for cobalt and chromium ion levels improved the sensitivity
and negative predictive value to 86% and 74% but at the expense
of specificity (27%) and positive predictive value (44%). Metal ion analysis is not recommended as a sole indirect screening
test in the surveillance of symptomatic patients with a MoM arthroplasty.
The investigating clinicians should have a low threshold for obtaining
cross-sectional imaging in these patients, even in the presence
of low plasma metal ion levels.
We retrospectively analysed concentrations of chromium and cobalt ions in samples of synovial fluid and whole blood taken from a group of 92 patients with failed current-generation metal-on-metal hip replacements. We applied acid oxidative digestion to our trace metal analysis protocol, which found significantly higher levels of metal ion concentrations in blood and synovial fluid than a non-digestive method. Patients were subcategorised by mode of failure as either ‘unexplained pain’ or ‘defined causes’. Using this classification, chromium and cobalt ion levels were present over a wider range in synovial fluid and not as strongly correlated with blood ion levels as previously reported. There was no significant difference between metal ion concentrations and manufacturer of the implant, nor femoral head size below or above 50 mm. There was a moderately positive correlation between metal ion levels and acetabular component inclination angle as measured on three-dimensional CT imaging. Our results suggest that acid digestion of samples of synovial fluid samples is necessary to determine metal ion concentrations accurately so that meaningful comparisons can be made between studies.