Early failure of articular surface replacement XL total hip arthroplasty

Long-term Follow-up on Revisions of a Recalled Large Head Metal-on-metal Hip Prosthesis: A Single Surgeon Series

Background

In 2010, a recall was issued for a specific monoblock large head metal-on-metal (MoM) hip prosthesis due to short-term revision rates of 12%-13% (articular surface replacement, DePuy Orthopaedics, Inc., Warsaw, IN). High complication, infection, and rerevision rates for revised MoM implants have been reported. The purpose of the study is to report long-term outcomes and trend metal ion levels of this recalled MoM prosthesis from a single surgeon series.

Methods

Retrospective chart review was performed on all patients that underwent revision of large MoM hip replacements between 2010 and 2015. Pre- and post-revision Harris Hip Score (HHS), cup abduction angles, anteversion angles, and cup sizes were compared. Survivorship and HHS were the primary outcomes measured; serum cobalt and chromium levels were secondary outcomes. Multivariate linear regression was used to examine the correlation between prerevision serum metal ion levels and HHS.

Results

A total of 24 hips (21 patients) met inclusion criteria. Mean time to revision was 4.12 years ± 1.1. Mean follow-up was 10.0 years (7-11.9 years). Mean HHS increased significantly after revision from 48.5 to 89.5 (P < .001). Higher prerevision cobalt levels were correlated with lower prerevision HHS (cobalt R = 0.25; chromium R = 0.3160). There was no correlation with prerevision cobalt (P = .2671) or chromium (P = .3160) with postrevision HHS. Most recent metal ion testing revealed a significant decrease in both cobalt (P = .0084) and chromium (P = .0115). Survival rate is 100%.

Conclusions

Our study showed excellent survivorship and outcomes at 10 years. There were no failures for any reason including infection. This differs from previous studies and confirms excellent long-term results are possible with revision of this recalled MoM implant.

[Translated article] Metal on metal total hip arthroplasty: Correlation between inclination of the acetabular and metal ion levels

Due to their low friction index, hip arthroplasties with metal-metal (M-M) friction torque have been an attractive option in young patients with high functional demand, currently they have suffered a decrease in their use due to the complications of some models and physiological reactions adverse reactions related to the elevation of metal ions in the blood. Our objective is to review the patients with M-M pair operated in our centre, correlating the ion level with the position of the acetabular component and with the size of the head.

MATERIAL AND METHODS

Retrospective review of 166 M-M hip prostheses operated between 2002 and 2011. Sixty five ruled out for different causes (death, loss of follow-up, no current ion control, no radiography or others), leaving a sample of 101 patients to be analysed. Follow-up time, cup inclination angle, blood ion level, Harris Hip Score (HHS), and complications were recorded.

RESULTS

One hundred and one patients (25 women and 76 men), 55 years of average age (between 26 and 70), of these 8 were surface prostheses and 93 total prostheses. The mean follow-up time was 10 years (between 5 and 17 years). The mean head diameter was 46.25 (between 38 and 56). The mean inclination of the butts was 45.7° (between 26° and 71°). The correlation force between the verticality of the cup and the increase in ions is moderate r=0.31 for Cr and slight r=0.25 for Co. The correlation force between head size and ion increase is weak and inverse r=-0.14 for Cr and r=0.1 for Co. Five patients (4.9%) required revision (2 [1%] due to increased ions with pseudotumor). The mean time to revision was 6.5 years in which the ions increased. The mean HHS was 94.01 (between 55.8 and 100). In the review of patients, we found 3 with a significant increase in ions who had not followed controls, all 3 had an HHS of 100. The angles of the acetabular components were 69°, 60° and 48° and the diameter of the head was 48.42 and 48mm, respectively.

DISCUSSION AND CONCLUSIONS

M-M prostheses have been a valid option in patients with high functional demand. A bi-annual analytical follow-up is recommended, since in our case we have detected 3 patients with HHS 100 who presented unacceptable elevation of cobalt >20μm/l (according to SECCA) of the ions and 4 with very abnormal elevation of cobalt ≥10μm/l (according to SECCA), all of them with cup orientation angles >50°. With our review we can conclude that there is a moderate correlation between the verticality of the acetabular component and the increase in blood ions and that the follow-up of this patient with angles >50° is essential.

Metal-on-Metal Hips: Ten-Year Clinical and Radiographic Outcomes of the ADEPT Metal-on-Metal Hip Resurfacing and Modular Total Hip Arthroplasty

BACKGROUND

The aim of this study is to update the 10-year follow-up survivorship and metal ions levels of a cohort of metal-on-metal (MoM) hip resurfacing (HR) and large-diameter-head (LDH) total hip arthroplasty (THA).

METHODS

The study is a retrospective analysis of prospectively collected data that compared the outcomes of 24 MoM HR (21 patients) and 15 (11 patients) modular LHD MoM THA at >10 years follow-up. Baseline characteristics as well as intraoperative and postoperative information were collected, including complications, revisions, clinical and radiographic outcomes, and serum metal ions level (Cobalt, Chromium). Metal ion levels were compared using a two-tailed unpaired t-test and Wilcoxon signed-rank test (jamovi v2.3.3.0, Sydney, NSW, AU).

RESULTS

No significant differences were detected in gender, BMI, and ASA score between the two groups. Patients in the modular THA group were significantly older (57 years vs. 46 years; p < 0.05). The HR overall survivorship was 91.7% (22 of 24 hips) with survivorship from implant failure and/or aseptic loosening and/or metal debris related 100% of problems. The modular THA overall survivorship was 86.7% (13 of 15 hips) with survivorship from implant aseptic loosening and metal ions complications of 93.4% (14 of 15 hips). No significant difference was noted when comparing clinical outcomes. Metal ions were significantly lower in the HR group (Co 25.8 nmol/L vs. 89 nmol/L; p < 0.001-Cr 33.5 nmol/L vs. 55.2 nmol/L; p = 0.026).

CONCLUSION

Both implants reported excellent and comparable clinical outcomes at >10 years follow-up. The Adept HR reported remarkable survivorship, in line with the registry data, proving once again its reliability in young active males. The modular LDH THA, despite being discontinued, presented higher reliability and a lower failure rate when compared with similar withdrawn MoM implants. Trunnionosis did not appear to be a significant problem in this particular modular design.

Metal on metal total hip arthroplasty: Correlation between inclination of the acetabular and metal ion levels

Due to their low friction index, hip arthroplasties with metal-metal (M-M) friction torque have been an attractive option in young patients with high functional demand, currently they have suffered a decrease in their use due to the complications of some models and physiological reactions adverse reactions related to the elevation of metal ions in the blood. Our objective is to review the patients with M-M pair operated in our center, correlating the ion level with the position of the acetabular component and with the size of the head.

MATERIAL AND METHODS

Retrospective review of 166 M-M hip prostheses operated between 2002 and 2011. Sixty five ruled out for different causes (death, loss of follow-up, no current ion control, no radiography or others), leaving a sample of 101 patients to be analyzed. Follow-up time, cup inclination angle, blood ion level, Harris Hip Score (HHS), and complications were recorded.

RESULTS

One hundred and one patients (25 women and 76 men), 55years of average age (between 26 and 70), of these 8 were surface prostheses and 93 total prostheses. The mean follow-up time was 10years (between 5 and 17years). The mean head diameters was 46.25 (between 38 and 56). The mean inclination of the butts was 45.7° (between 26° and 71°). The correlation force between the verticality of the cup and the increase in ions is moderate r=0.31 for Cr and slight r=0.25 for Co. The correlation force between head size and ion increase is weak and inverse r=-0.14 for Cr and r=0.1 for Co. Five patients (4.9%) required revision (2 [1%] due to increased ions with pseudotumor). The mean time to revision was 6.5years in which the ions increased. The mean HHS was 94.01 (between 55.8 and 100). In the review of patients, we found 3 with a significant increase in ions who had not followed controls, all 3 had an HHS of 100. The angles of the acetabular components were 69°, 60° and 48° and the diameter of the head was 48.42 and 48mm, respectively.

DISCUSSION AND CONCLUSIONS

M-M prostheses have been a valid option in patients with high functional demand. A bi-annual analytical follow-up is recommended, since in our case we have detected 3patients with HHS100 who presented unacceptable elevation of cobalt >20μm/L (according to SECCA) of the ions and 4 with very abnormal elevation of cobalt ≥10μm/L (according to SECCA), all of them with cup orientation angles >50°. With our review we can conclude that there is a moderate correlation between the verticality of the acetabular component and the increase in blood ions and that the follow-up of this patient with angles >50° is essential.

Ten-year outcomes following a cohort of ASR XL total hip arthroplasties

AIMS

To determine the outcome at 10 years of a cohort of ASR XL total hip arthroplasties (THAs) and reasons for revision.

METHODS

Between November 2005 and May 2007, 122 ASR XL THAs were implanted. All patients had a routine review at 6 weeks and 1 year, followed by a review in 2009 because of clinical concern and thereafter annual review up to 10 years with MRI. Review also included functional scores, radiographs, pain scores and blood metal ions.

RESULTS

67 (54.9%) ASR XLs had been revised by 11.1 years. Reasons for revision included pain (89.6%), high levels of cobalt and chromium ions (50.7%) and radiographic or MRI changes (80.6%). All 3 factors were present in 23 (34.3%). Pain at 1 year did not predict revision, but pain at the 2009 review did. At 10 years the revised patients had an average Oxford Hip Score (OHS) of 25.38 (12-42) and the non-revised 23.61 (2-21), the difference was not significant (p = 0.48). 3 patients (4.5%) have had a further revision; 2 for a previously unrevised stem and the other for instability.

CONCLUSIONS

Our arthroplasty care practitioner service allowed us to identify increased pain and stop using the ASR XL over 3 years before the implant was recalled. The revised patients had similar functional outcome to those unrevised. Poorly performing implants need to be identified earlier.

The end of the laboratory developed test as we know it? Recommendations from a national multidisciplinary taskforce of laboratory specialists on the interpretation of the IVDR and its complications

The in vitro diagnostic medical devices regulation (IVDR) will take effect in May 2022. This regulation has a large impact on both the manufacturers of in vitro diagnostic medical devices (IVD) and clinical laboratories. For clinical laboratories, the IVDR poses restrictions on the use of laboratory developed tests (LDTs). To provide a uniform interpretation of the IVDR for colleagues in clinical practice, the IVDR Task Force was created by the scientific societies of laboratory specialties in the Netherlands. A guidance document with explanations and interpretations of relevant passages of the IVDR was drafted to help laboratories prepare for the impact of this new legislation. Feedback from interested parties and stakeholders was collected and used to further improve the document. Here we would like to present our approach to our European colleagues and inform them about the impact of the IVDR and, importantly we would like to present potentially useful approaches to fulfill the requirements of the IVDR for LDTs.

Active Surveillance of the Implantable Cardioverter-Defibrillator Registry for Defibrillator Lead Failures

BACKGROUND

Several defibrillator leads have been recalled due to early lead failure leading to significant patient harm. Confirming the safety of contemporary defibrillator leads is essential to optimizing treatment for patients receiving implantable cardioverter-defibrillators (ICDs). We therefore sought to assess the comparative long-term safety of the 4 most commonly implanted ICD leads within the National Cardiovascular Data Registry ICD Registry.

METHODS AND RESULTS

A propensity-matched survival analysis of the ICD Registry was performed evaluating 4 contemporary ICD leads in patients receiving an ICD system for the first time. All patients in the ICD Registry aged ≥18 years who underwent an implant of an ICD between April 1, 2011 and March 31, 2016 were included. Monitoring of safety began with ICD implant and continued up to 5 years. A meaningful difference in ICD failure rate was defined as twice (or more) the lead failure rate observed in the propensity-matched comparator patients. Among the 374 132 patients who received a new ICD implant, no safety alerts were triggered for the primary safety end point of lead failure for any of the high energy leads studied. Estimated rates of freedom from lead failure at 5 years ranged from 97.7% to 98.9% for the 4 high-energy leads of interest.

CONCLUSIONS

Though limited by incomplete long-term outcomes ascertainment, active surveillance of the ICD Registry suggests that there were no meaningful differences in the rate of ICD high-energy lead survival for the 4 most commonly used high-energy ICD leads.

Superior patient reported outcome measures reported post Articular Surface Replacement (ASR) revision arthroplasty in the setting of an objective surgical indication

The Articular Surface Replacement (ASR) hip system displayed unexpectedly high failure rates. All patients who underwent revision arthroplasty at our institution were identified. Indications for revision were classified as objectively identifiable or performed for unexplained pain. Clinical outcomes, post ASR revision, were superior in cases where the aetiology for failure was identifiable. Pain and function improved reliably when a targeted objective indication was identified pre-revision, but failed to do so in cases of unexplained pain. Surgeons familiar with the results of this study will be empowered to discuss expectations and realistic outcomes with their patients undergoing complex revision arthroplasty cases.

Obesity is not associated with hip failure in patients with articular surface replacement of the hip

BACKGROUND

Our main aim was to investigate whether obese patients were at increased risk of elevated metal ion levels and/or adverse local tissue reaction (ALTR) after being treated with articular surface replacement (ASR) hip arthroplasty.

METHODS

This study included 360 patients who underwent metal-on-metal (MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). 95 patients (26%) were underweight/normal weight (BMI < 25 kg/m²), 139 (39%) were overweight (BMI 25-30 kg/m²), and 126 (36%) were obese (BMI ⩾ 30 kg/m²). Blood metal ion levels and patient-reported outcome measures (PROMs) were obtained, and a sub-cohort of 85 patients had MARS MRI performed. Logistic regression analyses were used to assess the associations between obesity and metal ions, as well as ALTR.

RESULTS

BMI was not associated with either elevated metal ion levels or ALTR. In HRA patients, female gender (OR 3.0; p = 0.019) and pain (OR 2.3; p = 0.046) were associated with elevated Co levels. Female patients had increased risk of elevated Cr levels (OR 3.0; p = 0.02). In THA patients, female gender (OR 2.2; p = 0.004) and VAS satisfaction (OR 2.1; p = 0.01) were associated with elevated Co levels. Female gender (OR 3.6; p = 0.001) and time from surgery (OR 1.4; p = 0.005) were associated with Cr levels. In the sub-cohort, ALTR was associated with Co levels (OR 16.1; p = 0.002) in HRA patients.

CONCLUSION

Patients with BMI ⩾ 30 kg/m² present no increased risk for elevated metal ion levels or development of ALTR.

Origins of material loss in highly worn acetabular cups of metal-on-metal total hip replacements

Excessive wear has been one of the major failure modes of metal-on-metal hip implants. From a collection of 541 retrieved ASR metal-on-metal implants, we selected those head-cup pairs with combined wear >100 mm³ , (N = 42) to assess the distributions of wear volume on cups, and non-conformance in the worn areas at the head-cup interfaces. All 42 had severe cup edge wear (average maximum wear depth 500 μm). On average, 58% of wear volume of cups occurred at the edge areas, whereas 42% occurred well inside the socket, indicating that substantial wear volume of cups was generated well inside the socket. Particularly, in eight cups, more than half of the wear volume occurred well inside the socket. The head-cup conformance in the worn areas was deteriorated. On average, in worn areas, head-cup clearance was approximately eight times greater than in unworn areas, and the sphericity of heads and cups was approximately 36 times and 84 times higher, respectively, than in unworn areas. The radius of curvature of the worn surfaces of heads and cups varied widely, with an average variation of 3 mm (0.6-7 mm) and 11 mm (2-47 mm) for heads and cups, respectively. The severely deteriorated conformance at the edge areas and the areas well inside the socket, due to edge contact, could be the major factor for excessive wear of these 42 pairs. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Recall of the ASR XL Head and Hip Resurfacing Systems

At the beginning of the 21st century, use of large-diameter, metal-on-metal devices was a popular procedure for hip replacement in young and physically active patients; however, within a few years, the number of revisions increased, resulting in a worldwide recall for the articular surface replacement (ASR) system. Complication rates for the ASR devices implanted at the authors' department are reported, with revision rates of 32% and 30% in the ASR XL Head and ASR Resurfacing groups, respectively. Reasons for revision surgery were serum metal ion elevation, luxation or subluxation, aseptic loosening, soft tissue compromise (adverse reactions to metal debris [ARMD]), and infection. The calculated implant survival for the ASR XL Head system and the ASR Resurfacing device (DePuy Orthopaedics Inc, Warsaw, Indiana) in the current series was 79% and 90%, respectively, at 60 months. Symptomatic patients with metal-on-metal devices, with or without elevated metal ion concentrations, should undergo cross sectional imaging to exclude ARMD. In cases of increased metal ion concentrations, local pain, or ARMD, revision surgery has to be evaluated. In the future, closer monitoring of new implants is needed to prevent high failure rates, as seen with the ASR design. Furthermore, the withdrawal of the device highlights the importance of national implant registries. [Orthopedics. 2017; 40(2):e340-e347.].

Medium term review of the ASR implant system: A single surgeon series

INTRODUCTION

Both ASR hip resurfacings and stemmed ASR XL arthroplasties have failed at high rates in several published series. We assessed a single surgeon series of these arthroplasties looking to identify factors associated with their failure.

METHODS

All surgeries were performed by one surgeon. Patients were evaluated clinically, radiologically and with serial cobalt and chromium ion analysis.

RESULTS

274 implants were analysed - 152 ASR resurfacings and 122 ASR XL implants. Thirty revisions were performed.

CONCLUSION

The failure rate of the ASR implant in our series is unacceptably high - its use in routine hip arthroplasty cannot be supported.

Registry-Based Prospective, Active Surveillance of Medical-Device Safety

BACKGROUND

The process of assuring the safety of medical devices is constrained by reliance on voluntary reporting of adverse events. We evaluated a strategy of prospective, active surveillance of a national clinical registry to monitor the safety of an implantable vascular-closure device that had a suspected association with increased adverse events after percutaneous coronary intervention (PCI).

METHODS

We used an integrated clinical-data surveillance system to conduct a prospective, propensity-matched analysis of the safety of the Mynx vascular-closure device, as compared with alternative approved vascular-closure devices, with data from the CathPCI Registry of the National Cardiovascular Data Registry. The primary outcome was any vascular complication, which was a composite of access-site bleeding, access-site hematoma, retroperitoneal bleeding, or any vascular complication requiring intervention. Secondary safety end points were access-site bleeding requiring treatment and postprocedural blood transfusion.

RESULTS

We analyzed data from 73,124 patients who had received Mynx devices after PCI procedures with femoral access from January 1, 2011, to September 30, 2013. The Mynx device was associated with a significantly greater risk of any vascular complication than were alternative vascular-closure devices (absolute risk, 1.2% vs. 0.8%; relative risk, 1.59; 95% confidence interval [CI], 1.42 to 1.78; P<0.001); there was also a significantly greater risk of access-site bleeding (absolute risk, 0.4% vs. 0.3%; relative risk, 1.34; 95% CI, 1.10 to 1.62; P=0.001) and transfusion (absolute risk, 1.8% vs. 1.5%; relative risk, 1.23; 95% CI, 1.13 to 1.34; P<0.001). The initial alerts occurred within the first 12 months of monitoring. Relative risks were greater in three prespecified high-risk subgroups: patients with diabetes, those 70 years of age or older, and women. All safety alerts were confirmed in an independent sample of 48,992 patients from April 1, 2014, to September 30, 2015.

CONCLUSIONS

A strategy of prospective, active surveillance of a clinical registry rapidly identified potential safety signals among recipients of an implantable vascular-closure device, with initial alerts occurring within the first 12 months of monitoring. (Funded by the Food and Drug Administration and others.).

Outcomes of the Recalled Articular Surface Replacement Metal-on-Metal Hip Implant System: A Systematic Review

BACKGROUND

The aim of this review was to synthesize the main findings of clinical studies that have evaluated outcomes of the articular surface replacement (ASR) Hip System.

METHODS

We performed a systematic literature search to identify all articles published between January 2008 and June 2015 that included ASR hip resurfacing arthroplasty (ASR HRA) or ASR total hip arthroplasty (ASR XL THA) outcomes according to the PRISMA statement.

RESULTS

A total of 56 studies were assessed. The prevalence of adverse local tissue reactions (ALTRs) and revision rates were found to be high. ALTR prevalence varied from 12.5% to 69% (mean, 33.5%). Mean revision rate for any reason at 4-year to 7-year follow-up was 13.8% (range, 5.6%-31%) for ASR HRA and 14.5% (range, 0%-37%) for ASR XL THA. Femoral head size <53 mm was found to correlate with higher blood metal ion levels. Femoral head size >44 mm was not associated with higher ALTR prevalence or revision rates in ASR XL THA. High blood metal ion levels (>7 μg/L Co, >7 μg/L Cr) were associated with higher failure rates and bearing-related complications. The role of cup positioning was found to be controversial.

CONCLUSION

ALTR prevalence and failure rates were high. High blood metal ion levels were a risk factor for ALTR and failure. Surprisingly, the role of cup positioning and large femoral head size in ASR XL THA were controversial. These findings should be considered in the clinical follow-up and risk stratification of patients with the ASR Hip System.

Metal in Total Hip Arthroplasty: Wear Particles, Biology, and Diagnosis

Total hip arthroplasty (THA) has been performed for nearly 50 years. Between 2006 and 2012, more than 600,000 metal-on-metal THA procedures were performed in the United States. This article reviews the production of metal wear debris in a metal-on-metal articulation and the interaction of cobalt and chromium ions that ultimately led to a dramatic decline in the use of metal-on-metal THA articulations. Additionally, the article reviews mechanisms of metal wear, the biologic reaction to cobalt and chromium ions, the clinical presentation of failing metal-on-metal articulations, and current diagnostic strategies. Further, the article discusses the use of inflammatory markers, metal ion levels, radiographs, metal artifact reduction sequence magnetic resonance imaging, and ultrasound for failed metal-on-metal THA procedures. When adopting new technologies, orthopedic surgeons must weigh the potential increased benefits against the possibility of new mechanisms of failure. Metal-on-metal bearings are a prime example of the give and take between innovation and clinical results, especially in the setting of an already successful procedure such as THA. [Orthopedics. 2016; 39(6):371-379.].

Retrospective cohort study of the performance of the Pinnacle metal on metal (MoM) total hip replacement: a single-centre investigation in combination with the findings of a national retrieval centre

OBJECTIVES

To determine risk factors for revision in patients implanted with a commonly used metal on metal (MoM) hip replacement.

DESIGN

Retrospective cohort study in combination with a prospective national retrieval study (Northern Retrieval Registry (NRR)).

SETTING

Combined orthopaedic unit in combination with the NRR.

PARTICIPANTS

All patients implanted with a DePuy Pinnacle MoM hip prostheses by the 2 senior authors were invited to attend for a review which included clinical examination, blood metal ion measurements, radiographs and targeted imaging. Explanted components underwent wear analysis using validated methodology and these results were compared with those obtained from the NRR.

RESULTS

489 MoM Pinnacle hips were implanted into 434 patients (243 females and 191 males). Of these, 352 patients attended the MoM recall clinics. 64 patients had died during the study period. For the purposes of survival analysis, non-attendees were assumed to have well-functioning prostheses. The mean follow-up of the cohort as a whole was 89 months. 71 hips were revised. Prosthetic survival for the whole cohort was 83.6% (79.9-87.3) at 9 years. The majority of explanted devices exhibited signs of taper junction failure. Risk factors for revision were bilateral MoM prostheses, smaller Pinnacle liners, and implantation in 2006 and later years. A significant number of devices were found to be manufactured out of their specifications. This was confirmed with analysis of the wider data set from the NRR.

CONCLUSIONS

This device was found to have an unacceptably high revision rate. Bilateral prostheses, those implanted into female patients and devices implanted in later years were found to be at greater risk. A significant number of explanted components were found to be manufactured with bearing diameters outside of the manufacturer's stated tolerances. Our findings highlight the clinical importance of hitherto unrecognised variations in device production.

Prevalence of Failure due to Adverse Reaction to Metal Debris in Modern, Medium and Large Diameter Metal-on-Metal Hip Replacements--The Effect of Novel Screening Methods: Systematic Review and Metaregression Analysis

Metal-on-metal (MoM) hip replacements were used for almost a decade before adverse reactions to metal debris (ARMD) were found to be a true clinical problem. Currently, there is a paucity of evidence regarding the usefulness of systematic screening for ARMD. We implemented a systematic review and meta-analysis to establish the prevalence of revision confirmed ARMD stratified by the use of different screening protocols in patients with MoM hip replacements. Five levels of screening were identified: no screening (level 0), targeted blood metal ion measurement and/or cross-sectional imaging (level 1), metal ion measurement without imaging (level 2), metal ion measurement with targeted imaging (level 3) and comprehensive screening (both metal ions and imaging for all; level 4). 122 studies meeting our eligibility criteria were included in analysis. These studies included 144 study arms: 100 study arms with hip resurfacings, 33 study arms with large-diameter MoM total hip replacements (THR), and 11 study arms with medium-diameter MoM THRs. For hip resurfacing, the lowest prevalence of ARMD was seen with level 0 screening (pooled prevalence 0.13%) and the highest with level 4 screening (pooled prevalace 9.49%). Pooled prevalence of ARMD with level 0 screening was 0.29% and with level 4 screening 21.3% in the large-diameter MoM THR group. In metaregression analysis of hip resurfacings, level 4 screening was superior with regard to prevalence of ARMD when compared with other levels. In the large diameter THR group level 4 screening was superior to screening 0,2 and 3. These outcomes were irrespective of follow-up time or study publication year. With hip resurfacings, routine cross-sectional imaging regardless of clinical findings is advisable. It is clear, however, that targeted metal ion measurement and/or imaging is not sufficient in the screening for ARMD in any implant concepts. However, economic aspects should be weighed when choosing the preferred screening level.

Stem Migration and Fretting Corrosion of the Antirotation Pin in the K2/Apex Hip System

BACKGROUND

Many exchangeable neck hip systems have been withdrawn because of fretting corrosion at the neck/stem coupling.

METHOD

Our prospective randomized study evaluating stem stability (Roentgen stereophotogrammetric analysis, dual-energy x-ray absorptiometry) and clinical outcomes between the K2/Apex hip systems was ceased early because of a withdrawal of the stems which had an unfavorably high early revision rate reported in the Australian Orthopaedic Association National Joint Registry (9.3% at 3 years).

RESULTS

At 2 years, there are no clinical differences between the stems. Roentgen stereophotogrammetric analysis has identified a high proportion of potentially concerning subsidence and retroversion in both groups, more marked in the K2 stem, although mostly in asymptomatic patients. Dual-energy x-ray absorptiometry has shown similar bone density around the stems. Retrieval analysis of 3 study patients showed fretting corrosion of the antirotation pin and aseptic lymphocyte-dominated vasculitis-associated lesion, with no relationship to bearing type or size. Analysis of 7 further nonstudy K2/Apex stems confirmed similar corrosion.

CONCLUSION

This study shows potentially concerning subsidence of both stems and is the first to describe corrosion at the neck-stem interface and a relationship to metal-related pathology.

Revision of Articular Surface Replacement (ASR) Total Hip Arthroplasty: Correlation of Perioperative Data and Early Post-Revision Outcome Results

The articular surface replacement (ASR) total hip arthroplasty (THA) showed accelerated failure rates due to adverse-reaction to metal debris (ARMD). Literature correlating preoperative with intraoperative revision findings respectively post-revision outcome results are rare. 30 of 99 available ASR THA were revised due to ARMD. Mean post-revision follow-up term was 2.3 years. In part, preoperative data did not correlate with intraoperative revision findings. ARMD was even found in asymptomatic patients with non-elevated ion levels. Postoperative pain and metal ions decreased significantly (P ≤ 0.016). Cobalt decreased faster than chrome. Patients with intraoperative pseudotumors, osteolysis or bilateral THA did not have higher pre- or postoperative ion values (P ≥ 0.053). Females showed higher postoperative chrome levels (P=0.031). One major post-revision complication (femoral nerve palsy) and one re-revision (late onset infection) occurred.

Large-diameter metal-on-metal total hip arthroplasty: dislocation infrequent but survivorship poor

BACKGROUND

Use of large-diameter metal-on-metal (MoM) articulations in THA increased, at least in part, because of the possibility of achieving improved joint stability and excellent wear characteristics in vitro. However, there have been subsequent concerning reports with adverse reactions to metal debris (ARMD), pseudotumors, and systemic complications related to metal ions.

QUESTIONS/PURPOSES

The purpose of this study was to determine at a minimum of 2 years' followup (1) the proportion of patients who experienced a dislocation; (2) the short-term survivorship obtained with these implants; (3) the causes of failure and the proportion of patients who developed ARMD; and (4) whether there were any identifiable risk factors for revision.

METHODS

We reviewed the results of 1235 patients who underwent 1440 large-diameter MoM primary THAs at our institution using two acetabular devices from a single manufacturer with minimum 2-year followup. Large-diameter MoM devices were used in 48% (1695 of 3567) of primary THAs during the study period. We generally used these implants in younger, more active, higher-demand patients, in patients considered at higher risk of instability, and in patients with adequate bone stock to achieve stable fixation without use of screws. Clinical records and radiographs were reviewed to determine the incidence and etiology of revision. Patients whose hips were revised were compared with those not revised to identify risk factors; Kaplan-Meier survivorship analysis was performed as was multivariate analysis to account for potential confounding variables when evaluating risk factors. Minimum followup was 2 years (average, 7 years; range, 2-12 years); complete followup was available in 85% of hips (1440 of 1695).

RESULTS

Dislocation occurred in one hip overall (<1%; one of 1440). Kaplan-Meier analysis revealed survival free of component revision was 87% at 12 years (95% confidence interval, 84%-90%). The two most common indications for revision were ARMD (48%; 47 of 108 hips revised) and loosening or failure of ingrowth (31%; 34 of 108). Risk factors for component revision were younger age at surgery (relative risk [RR] 0.98 per each increased year; p=0.02), higher cup angle of inclination (RR 1.03 per each increased degree; p=0.04), and female sex (RR 1.67; p=0.03).

CONCLUSIONS

Large-diameter MoM THAs are associated with a very low dislocation rate, but failure secondary to ARMD and loosening or lack of ingrowth occur frequently. Patients with MoM THA should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Early diagnosis and appropriate treatment are recommended to prevent the damaging effects of advanced ARMD.

LEVEL OF EVIDENCE

Level IV, Therapeutic study.

The data extraction and longitudinal trend analysis network study of distributed automated postmarket cardiovascular device safety surveillance

BACKGROUND

Current approaches for postmarket medical device safety surveillance are limited in their ability to produce timely and accurate assessments of adverse event rates.

METHODS AND RESULTS

The Data Extraction and Longitudinal Trend Analysis (DELTA) network study was a multicenter prospective observational study designed to evaluate the safety of devices used during percutaneous coronary interventions. All adult patients undergoing percutaneous coronary intervention from January 2008 to December 2012 at 5 participating Massachusetts sites were included. A safety alert was triggered if the cumulative observed adverse event rates for the study device exceeded the upper 95% confidence interval of the event rates of propensity-matched control cohort. Prespecified sensitivity analyses were developed to validate any identified safety signal. A total of 23,805 consecutive percutaneous coronary intervention procedures were evaluated. Two of 24 safety analyses triggered safety alerts. Patients receiving Perclose vascular closure device experienced an increased risk of minor vascular complications (relative risk, 4.14; P<0.01) and any vascular complication (relative risk, 2.06; P=0.01) when compared with propensity-matched patients receiving alternative vascular closure device, a result primarily driven by relatively high event rates at 1 participating center. Sensitivity analyses based on alternative risk adjustment methods confirmed a pattern of increased rate of complications at 1 of the 5 participating sites in their use of Perclose vascular closure device.

CONCLUSIONS

The DELTA network study demonstrates that distributed automated prospective safety surveillance has the potential of providing near real-time assessment of safety risks of newly approved medical devices.

Implication of femoral stem on performance of articular surface replacement (ASR) XL total hip arthroplasty

Taper junctions of large diameter metal-on-metal femoral heads and femoral stems were described as metal ion generator due to accelerated wear and corrosion. However, literature about the Articular Surface Replacement (ASR) total hip arthroplasty (THA) invariably deals with stems manufactured by DePuy Orthopedics (Warsaw, IN, USA). Nothing is known whether different stems with common 12/14 mm tapers affect failure rate or ion release. 99 ASR THA (88 patients) implanted with CoxaFit or ARGE Geradschaft stems (K-Implant, Hannover, Germany) were retrospectively analyzed. After a mean follow-up of 3.5 years revision rate was 24.5%, mostly due to adverse reaction to metal debris (ARMD). CT scan revealed component loosening in 10.3% and pseudotumoral lesions in 12.6%. Elevated ion concentrations (>7 μg/l) were found in 38.6%.

MRI findings following metal on metal hip arthroplasty and their relationship with metal ion levels and acetabular inclination angles

Following the global recall of all ASR metal on metal hip products, our aim was to correlate MRI findings with acetabular inclination angles and metal ion levels in patients with these implants. Both cobalt and chromium levels were significantly higher in the presence of a periprosthetic fluid collection. There was no association between the presence of a periprosthetic mass, bone marrow oedema, trochanteric bursitis or greater levels of abductor muscle destruction for cobalt or chromium. There was no association between the level of periprosthetic tissue reaction and the acetabular inclination angle with any of the pathologies identified on MRI. The relationship between MRI pathology, metal ion levels and acetabular inclination angles in patients with ASR implants remains unclear adding to the complexity of managing patients.

Early failures in total hip arthroplasty -- a changing paradigm

Between 2001 and 2011, 1168 revision hip arthroplasties were reviewed for "early" failures within 5 years of the primary total hip arthroplasty (THA). 24.1% underwent revision within 5 years of index THA. Aseptic loosening, infection, instability, metallosis, and fracture were common modes of failure. In our previous report from 1986 to 2000, 33% were "early" revisions, with instability and aseptic loosening accounting for over 70% of these early failures. While the proportion of "early" revisions decreased 9% from our previous report, this rate remains alarming. The emergence of metallosis and aseptic loosening of monoblock metal on metal shells as leading causes of early failures is concerning. This report suggests caution in the early adoption of new innovations before evidence based medicine is available to justify the risk of their use.

On the inflammatory response in metal-on-metal implants

Background

Metal-on-metal implants are a special form of hip endoprostheses that despite many advantages can entail serious complications due to release of wear particles from the implanted material. Metal wear particles presumably activate local host defence mechanisms, which causes a persistent inflammatory response with destruction of bone followed by a loosening of the implant. To better characterize this inflammatory response and to link inflammation to bone degradation, the local generation of proinflammatory and osteoclast-inducing cytokines was analysed, as was systemic T cell activation.

Methods

By quantitative RT-PCR, gene expression of cytokines and markers for T lymphocytes, monocytes/macrophages and osteoclasts, respectively, was analysed in tissue samples obtained intraoperatively during exchange surgery of the loosened implant. Peripheral T cells were characterized by cytofluorometry before surgery and 7 to 10 days thereafter.

Results

At sites of osteolysis, gene expression of cathepsin K, CD14 and CD3 was seen, indicating the generation of osteoclasts, and the presence of monocytes and of T cells, respectively. Also cytokines were highly expressed, including CXCL8, IL-1ß, CXCL2, MRP-14 and CXCL-10. The latter suggest T cell activation, a notion that could be confirmed by detecting a small, though conspicuous population of activated CD4+ cells in the peripheral blood T cells prior to surgery.

Conclusion

Our data support the concept that metallosis is the result of a local inflammatory response, which according to histomorphology and the composition of the cellular infiltrate classifies as an acute phase of a chronic inflammatory disease. The proinflammatory environment, particularly the generation of the osteoclast-inducing cytokines CXCL8 and IL1-ß, promotes bone resorption. Loss of bone results in implant loosening, which then causes the major symptoms of metallosis, pain and reduced range of motion.

The effect of acetabular inclination on metal ion levels following metal-on-metal hip arthroplasty

Acetabular inclination angles have been suggested as a principal determinant of circulating metal ion levels in metal-on-metal hip arthroplasties. We aimed to determine whether inclination angle correlates with ion levels in arthroplasties using the Articular Surface Replacement (ASR) system. Patients undergoing ASR arthroplasties had blood metal ion levels and radiograph analysis performed a mean of 3.2 years after surgery. Inclination angle showed only a weak correlation with cobalt (r=0.21) and chromium (r=0.15) levels. The correlation between inclination angle and cobalt levels was significant only with small femoral components, although it was still weak. Multiple regression showed a complex interaction of factors influencing ion levels but inclination angle accounted for little of this variation. We conclude that the acetabular inclination angle is not a meaningful determinant of metal ion levels in ASR arthroplasties.

A minimum 5-year follow-up of an oxidized zirconium femoral prosthesis used for total knee arthroplasty

BACKGROUND

Bearing surface wear remains a potential concern amongst younger patients undergoing total knee arthroplasty (TKA). Because of the potential for lower prosthetic wear rates, oxidized zirconium is a potentially attractive bearing surface for TKA in young, active patients. This material is also well suited for patients with suspected nickel sensitivities as it has no measurable nickel content, in contrast to standard femoral bearings made of cobalt-chromium alloys. Although in vitro testing on knee wear simulators has demonstrated favorable wear characteristics of oxidized zirconium compared to traditional cobalt-chrome bearings, in vivo clinical outcome data with this novel bearing surface are sparse.

METHODS

We retrospectively reviewed 109 consecutive TKAs in 82 patients at a minimum of five years postoperatively to determine prosthetic survivorship and to assess whether any adverse clinical consequences could be attributed to this bearing. Knees were evaluated with Knee Society scores, UCLA activity scores, clinical examinations, and radiographs. The mean age for this cohort was 58.7 years.

RESULTS

Survivorship free of bearing related complications was 100% at a minimum of five years post-surgery. There were no revisions for loosening, osteolysis, implant failure, or deep infection. There were no knees with radiographic failure, visible wear, loosening, or osteolysis.

CONCLUSION

Oxidized zirconium remains an attractive option for patients with nickel sensitivities and in those patients at risk for prosthetic wear due to young age or high activity levels.

Radiographically undetectable periprosthetic osteolysis with ASR implants: the implication of blood metal ions

Patients with ASR implants (resurfacing and large-diameter (XL) metal-on-metal (MoM) total hip arthroplasty), even if asymptomatic and with a stable prosthesis, may present extremely high blood metal ion levels. We report on a consecutive series of fourteen ASR revisions, focusing on osteolysis and their radiographic correspondence and their correlation with blood metal ion levels. At revision, seven hips revealed severe periacetabular osteolysis which was radiographically undetectable in six and asymptomatic in five. Seven hips with no acetabular osteolysis had significantly lower serum Cr and Co ion concentrations (respectively 25.2, 41.1 μg/l) compared to the seven hips with severe acetabular bone loss (respectively 70.1, 147.0 μg/l). Elevated blood metal ion levels should be considered as a warning of undetectable and ongoing periprosthetic osteolysis in asymptomatic patients with ASR prosthesis.

Poor short term outcome with a metal-on-metal total hip arthroplasty

Metal-on-metal (MoM) bearings for total hip arthroplasty (THA) have come under scrutiny with reports of high failure rates. Clinical outcome studies with several commercially available MoM THA bearings remain unreported. We evaluated 78 consecutive MoM THAs from a single manufacturer in 68 patients. Sixty-six received cobalt-chrome (CoCr) monoblock and 12 received modular titanium acetabular cups with internal CoCr liners. Femoral components were titanium with modular necks. At average 2.1 years postoperatively, 12 THAs (15.4%) demonstrated aseptic failure (10 revisions, 2 revision recommended). All revised hips demonstrated capsular necrosis with positive histology reaction for aseptic lymphocytic vasculitis-associated lesions/adverse local tissue reactions. Prosthetic instability following revision surgery was relatively common. Female gender was a strong risk factor for failure, though smaller cups were not. Both monoblock and modular components fared poorly. Corrosion was frequently observed around the proximal and distal end of the modular femoral necks.

The withdrawn ASR™ THA and hip resurfacing systems: how have our patients fared over 1 to 6 years?

BACKGROUND

The Articular Surface Replacement™ (ASR™) metal-on-metal hip arthroplasty system (DePuy Orthopaedics, Inc, Warsaw, IN, USA) reportedly has a higher than anticipated early failure rate leading to a voluntary recall. This prompted us to evaluate all ASR™ components implanted at our center.

QUESTIONS/PURPOSES

In all ASR™ components, we reported (1) revision rate, (2) blood metal ion levels, and (3) intraoperative findings for revisions related to adverse reaction to metal debris (ARMD).

METHODS

We retrospectively reviewed all 172 patients (190 hips) who underwent THA (149 hips) or hip resurfacing (41 hips) with the ASR™ system. We determined failure rates. We obtained blood metal ion concentrations from 93 patients at last followup. We evaluated MRI studies and intraoperative histopathology. Minimum followup was 12 months (mean, 40 months; range, 12-74 months).

RESULTS

At latest followup, we had revised 24 of 190 hips (13%): in 18 patients with THA and five patients with resurfacing. Mean time to revision was 45 months (range, 12-75 months). Mean blood concentrations were 13 μg/L (range, 0-150 μg/L) for cobalt and 6 μg/L (range, 0-87 μg/L) for chromium. Mean prerevision blood metal ion levels were higher in the revised group (cobalt: 48 μg/L; chromium: 18 μg/L) than in the nonrevised group (cobalt: 5 μg/L; chromium: 2 μg/L). ARMD was present in 14 of the 24 hips revised in this study.

CONCLUSIONS

Surgeons must have a low threshold for concern for ARMD in patients with ASR™ systems. Blood metal ion levels and MRI can be used to evaluate patients with underperforming implants. Intraoperative histopathologic analysis and joint fluid cytology can help diagnose ARMD at the time of revision.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Can we trust studies published by authors with financial conflicts? Using the decline of metal-on-metal total hip arthroplasty to investigate

The objective of our study was to determine if authors with conflicts of interest are less likely to report negative study outcomes in metal-on-metal total hip arthroplasty. We performed a systematic review of 3 major orthopedic journals for articles related to metal-on-metal total hip arthroplasty over 12 years. A total of 64 studies reported clinical outcomes and were included. Reviewers assigned a positive, neutral, or negative label. Each study was noted for the presence of absence of a financial conflict. There was a significant trend from positive to negative study outcomes over time (P = .015). A similar negative trend was seen in studies written by authors with financial disclosures (P = .021). Authors with financial conflicts have contributed to the increase in negative outcomes reported in the literature.