Aims. We investigated whether
Purpose. Total shoulder arthroplasty (TSA) has become a successful treatment option for degenerative shoulder disease. With the increasing incidence in primary TSA procedures during the last decades, strategies to improve implant longevity become more relevant. Implant failure is mainly associated with mechanical or biological causes. Chronic inflammation as a response to wear particle exposure is regarded as a main biological mechanism leading to implant failure. Metal ions released by fretting and corrosion at modular taper connections of orthopedic implants can cause cell-mediated hypersensitivity reactions and might lead to aseptic loosening. Modularity is also commonly used in total shoulder replacement. However, little is known about metal ion exposure in patients following TSA. The objective of this study was to determine in-vivo
A concern of metal on metal hip resurfacing arthroplasty is long term exposure to Cobalt (Co) and Chromium (CR) wear debris from the bearing. This study compares whole
High short-term failure rates have been observed with a number of metal-on-metal (MoM) hip designs. Most patients require follow-up with
Metal ion levels are used to track the performance of metal containing bearings in hip replacement patients. Changes in whole
Objectives. Alarm over the reported high failure rates for metal-on-metal (MoM) hip implants as well as their potential for locally aggressive Adverse Reactions to Metal Debris (ARMDs) has prompted government agencies, internationally, to recommend the monitoring of patients with MoM hip implants. Some have advised that a blood ion level >7 µg/L indicates potential for ARMDs. We report a systematic review and meta-analysis of the performance of metal ion testing for ARMDs. Methods. We searched MEDLINE and EMBASE to identify articles from which it was possible to reconstruct a 2 × 2 table. Two readers independently reviewed all articles and extracted data using explicit criteria. We computed a summary receiver operating curve using a Bayesian random-effects hierarchical model. Results. Our literature search returned 575 unique articles; only six met inclusion criteria defined a priori. The discriminative capacity of ion tests was homogeneous across studies but that there was substantial cut-point heterogeneity. Our best estimate of the “true” area under curve (AUC) for metal ion testing is 0.615, with a 95% credible interval of 0.480 to 0.735, thus we can state that the probability that metal ion testing is actually clinically useful with an AUC ≥ 0.75 is 1.7%. Conclusion. Metal ion levels are not useful as a screening test for identifying high risk patients because ion testing will either lead to a large burden of false positive patients, or otherwise marginally modify the pre-test probability. With the availability of more accurate non-invasive tests, we did not find any evidence for using blood ion levels to diagnose symptomatic patients. Cite this article: M. Pahuta, J. M. Smolders, J. L. van Susante, J. Peck, P. R. Kim, P. E. Beaule.
The search for the ideal bearing surface in Total Hip Replacements continues. The current ‘best’ materials are felt to be combinations of metal, ceramics and cross-linked polyethylene. Laboratory studies suggest that ceramic-on-metal articulations may provide distinct advantages. This study aims to identify the best bearing surface combination with the lowest adverse side effect profile. Between February 2004 and September 2007, 164 hips were replaced in 142 patients. 39% were male and 69% were female. The average age at surgery was 53 years (17-72 years). Follow-up assessment included radiographs, the Harris Hip Score and whole blood samples for metal ion levels. Complications to date included 3 hips which needed femoral revision because of surgery related factors, and 3 cases of sepsis of which 1 settled and 2 needed revision. One hip needed revision of head and liner to a larger bearing size for recurrent dislocations, and is no longer being followed up for
There are several component position and design variables that increase the risk of edge loading and high wear in metal-on-metal hip resurfacing (MOM-HR). In this study we combined all of these variables to calculate the ‘contact patch to rim distance’ (CPRD) in patients undergoing revision of their MOM-HR. We then determined whether CPRD was more strongly correlated with component wear and
Introduction. A metal ion study was undertaken in patients who had received an articular surface replacement. The design of these components is optimised in line with lubrication theory and produces low levels of wear in hip joint simulators. Methods. Patients were recruited in four centres. Whole blood samples were analysed for metal ion levels using high resolution ICP-MS (inductively coupled plasma mass spectrophotometry). A total of 75 patients was enrolled into the study and 65 and 47 patients were assessed after 12 and 24 months implantation respectively. Results are included irrespective of clinical outcome. Results. The 12 and 24 month median ion levels were 1.4 μg/l and 1.6 μg/l respectively for chromium and 1.5(μg/l and 1.6 μg/l respectively for cobalt. The pre-operative levels were 0.38(μg/l and 0.34(μg/l for chromium and cobalt respectively. Twenty-seven percent of patients had a pre-operative chromium level that was higher than the 24 month median level. Similarly the value for cobalt was seven percent. However close examination of the data shows that it is skewed by 6 outliers with cobalt or chromium levels greater than 10(μg/l after 24 months implantation. This appears to be related to acetabular component placement. Patients with acetabular components implanted at a high inclination angle (>55deg) are more likely to have elevated metal ion levels compared with a standard angle (<55deg). In the 24 month group two patients (both outliers) have been revised. Furthermore, the high metal ion levels at 24 months could be predicted by intermediate levels after 12 months. Conversely those levels below 10ug/l had already stabilised after 12 months in vivo. Conclusion. Large diameter metal-on-metal bearing with optimised tolerances can produce very low
Objectives. The aims of this piece of work were to: 1) record the background
concentrations of blood chromium (Cr) and cobalt (Co) concentrations
in a large group of subjects; 2) to compare blood/serum Cr and Co
concentrations with retrieved metal-on-metal (MoM) hip resurfacings;
3) to examine the distribution of Co and Cr in the serum and whole
blood of patients with MoM hip arthroplasties; and 4) to further
understand the partitioning of metal ions between the serum and
whole blood fractions. Methods. A total of 3042 blood samples donated to the local transfusion
centre were analysed to record Co and Cr concentrations. Also, 91
hip resurfacing devices from patients who had given pre-revision
blood/serum samples for metal ion analysis underwent volumetric
wear assessment using a coordinate measuring machine. Linear regression analysis
was carried out and receiver operating characteristic curves were
constructed to assess the reliability of metal ions to identify
abnormally wearing implants. The relationship between serum and
whole blood concentrations of Cr and Co in 1048 patients was analysed
using Bland-Altman charts. This relationship was further investigated
in an in vitro study during which human blood was
spiked with trivalent and hexavalent Cr, the serum then separated
and the fractions analysed. Results. Only one patient in the transfusion group was found to have a
blood Co >
2 µg/l. Blood/Serum Cr and Co concentrations were reliable
indicators of abnormal wear. Blood Co appeared to be the most useful
clinical test, with a concentration of 4.5 µg/l showing sensitivity
and specificity for the detection of abnormal wear of 94% and 95%, respectively.
Generated metal ions tended to fill the serum compartment preferentially in
vivo and this was replicated in the in vitro study
when blood was spiked with trivalent Cr and bivalent Co. Conclusions.
Background: Definitive cup position for the reduction of
Background:
The search for the ideal bearing surfaces to be used in Total Hip Replacement continues. The current “best” materials are felt to be various combinations of metal, ceramics and cross-linked polyethylene. Laboratory studies suggest that ceramic-on-metal articulations may provide distinct advantages. This study aims to identify the best combination with the lowest side effect profile. In February 2004 a prospective randomised trial on different bearing surfaces was started. The combinations selected were ceramic-on-cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal and ceramic-on-metal. Institutional ethics clearance was obtained. In all patients uncemented femoral stems are used, with an uncemented porocoated acetabular shell. A uniform 28mm femoral head size was selected. Blood samples have been taken to measure the metal ion concentrations in all patients. These are measured pre operatively, and repeated at follow up visits at 3 months and 1 year, with further follow up at 3,5 and 10 years post operatively. Whole blood ion levels are measured using a graphite furnace atomic absorption spectrometer. Between February 2004 and April 2006 one hundred and ten hips have undergone total hip replacement. There are 105 patients (5 bilateral). 40% are males and 60% female. The average age at operation is 52 years (17 to 72). 49% hips are left and 51% right. Follow up includes blood samples and the Harris Hip Score. Complications to date have been surgeon related, with three femoral components needing early revision for technical reasons. This has not affected the bearing surfaces. Radiological and clinical assessment shows no difference between the different bearing surface groups. Post operative whole
There have been no large comparative studies of the blood levels of metal ions after implantation of commercially available hip resurfacing devices which have taken into account the effects of femoral size and inclination and anteversion of the acetabular component. We present the results in 90 patients with unilateral articular surface replacement (ASR) hip resurfacings (mean time to blood sampling 26 months) and 70 patients with unilateral Birmingham Hip Resurfacing (BHR) implants (mean time 47 months). The whole blood and serum chromium (Cr) and cobalt (Co) concentrations were inversely related to the size of the femoral component in both groups (p <
0.05). Cr and Co were more strongly influenced by the position of the acetabular component in the case of the ASR, with an increase in metal ions observed at inclinations >
45° and anteversion angles of <
10° and >
20°. These levels were only increased in the BHR group when the acetabular component was implanted with an inclination >
55°. A significant relationship was identified between the anteversion of the BHR acetabular component and the levels of Cr and Co (p <
0.05 for Co), with an increase observed at anteversion angles <
10° and >
20°. The median whole blood and serum Cr concentrations of the male ASR patients were significantly lower than those of the BHR men (p <
0.001). This indicates that reduced diametral clearance may equate to a reduction in metal ion concentrations in larger joints with satisfactory orientation of the acetabular component.
Introduction: The purpose of this retrospective study is to compare long-term whole
Metal-metal surface replacement (MoMSRA) continues to be used in young women. Systemic metal ion release and its effects cause concern. Do metal ions crossing the placenta in pregnant women have potential mutagenic effects? The hypothesis is that metal ions pass freely through the placenta and there is no difference in maternal and cord metal levels. This is a controlled cross-sectional study of women with MoMSRA. (n = 25, 3 bilateral, mean age 32 years, time from implantation to delivery 60 months). The control group consisted of 24 subjects, mean age 31 years, with no metallic implant and not receiving cobalt/chromium supplements. No patient was known to have renal failure. Whole blood specimens were obtained before delivery and before any infusion or transfusion, and cord blood specimens immediately after delivery.Introduction
Methods
The combination of a ceramic head articulating against a metal acetabular liner (CoM) has shown reduced metal ion levels compared with a metal-on-metal bearing (MoM) in hip simulator studies. A randomized prospective clinical trial was undertaken using CoM and MoM bearings in an otherwise identical total hip procedure. The initial clinical results were encouraging. This report comprises a further review of metal ion data. Patients received identical components with the exception of the bearing surface material but all were 28mm diameter. All components were supplied by DePuy International Ltd. Patients were assessed pre-operatively, 3m, 12m and >
24m (median 32m). Whole blood samples were collected at regular follow-ups, frozen and analysed in batches using high resolution Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). All recruited patients are included irrespective of outcome. However some patients failed to attend specific follow-ups and some contaminated samples had to be discarded. Statistical significance was analyzed using a non-parametric comparison (Mann-Whitney test). After 3m and 12m implantation there were between 21 and 24 patients available for analysis in both the CoM and MoM cohort and after >
24m point 10 and 9 respectively. There were four outliers (either Cr or Co >
10ug/l) in both the CoM and MoM groups. In common with previous studies (with the exception of two marginal outliers), these were related to component position. They were implanted with either a cup abduction angle of >
55°, an anteversion angle of >
30° or both. Other studies with the same design of component have reported no significant outliers. The median Cr and the Co levels are lower with the CoM bearing compared with the MoM at all measurements points following implantation. The median background (pre-operative) levels for the combined CoM and MoM group were Cr: 0.22ug/l and Co: 0.49ug/l. These were significantly different (p=0.006). In the CoM group, the median 12m Cr and Co values were 0.43ug/l and 0.72ug/l respectively. The comparable values for MoM are 0.68ug/l and 0.83ug/l. Increases in metal ion levels from pre-operative levels are used as the primary ion level outcome in this study because the background level will comprise of the order of 30–50% of the overall value. The increase in Cr for CoM and MoM from pre-op levels to 12m significantly different for Cr (p=0.015). It has a lower significance for combined metal ion levels (p=0.029). This difference in not significant for Co (p=0.195). In agreement with predictions from hip simulator studies, CoM bearings in this study produced lower levels of metal ions than comparable MoM bearings at all time points. However the difference is less than that predicted in the laboratory and is much more pronounced with Cr than with Co.
Orthopaedic cobalt chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials, especially those liberated by orthopaedic implants, is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers.
A two sample t-test demonstrated cobalt and chromium ion levels were significantly higher in patients with abnormalities on USS (p=0.038, p=0.05 respectively), patients with normal USS were more likely to have a retroverted femoral component (p=0.01).
We have previously described the relationship between wear rates of MOM components and soft tissue necrosis. In this study we investigated the link between wear rates, metal ion concentrations and osteolysis. All unilateral patients who underwent revision of hip resurfacings at our centre were included. Retrieved components were analysed using a coordinate measuring machine to determine total volumetric material loss and rates of wear. Given the accuracy of the wear calculations (which we have previously published), wear rates were considered “abnormal” if ≥3mm3/yr. ROC curves were constructed to determine a Co concentration which would be clinically useful to detect abnormal wear. During revision, the presence/absence of osteolysis was documented.Background
Methods