Hip Resurfacing News - Metal Ion Issues

ASR Recall by DePuy 2010

nospam@example.com (Patricia Walter) — Fri, 03 Sep 2010 09:24:25 -0700

DePuy has announced that it is voluntarily recalling the ASR™ XL Acetabular Head System and DePuy ASR™ Hip Resurfacing System. DePuy is providing the information below to help visitors with questions and concerns. Visitors are also invited to visit the DePuy website at www.depuy.com.

DePuy makes patient safety and health a top priority and is continually evaluating data about its products. Most ASR hip replacement surgeries have been successful. However, data recently received by the company shows that more people than expected who received the ASR hip experienced pain and other symptoms that lead to a second hip replacement surgery, called a revision surgery.
For this reason, DePuy Orthopaedics is recalling its ASR™ XL Acetabular Head System and DePuy ASR™ Hip Resurfacing System. This recall means additional testing and monitoring may be necessary in hip replacement patients. In some cases, patients may need additional surgery.
DePuy is working closely with health care professionals worldwide to contact patients with ASR hip implants. Most people with ASR Hip System implants do not experience problems, but it is important that patients with ASR Hip System implants be evaluated with by a surgeon. Patients with problems reported different symptoms with their ASR hip implant, including pain, swelling, and problems walking.

DePuy intends to cover reasonable and customary costs of monitoring and treatment for services, including revision surgeries, associated with the recall of ASR.

Click here for the press release

Click here for the patient information page on our web site

Click here for an image of the ASR Hip System

Medical Release Form:

Patients with an ASR Hip are asked to complete the form and bring it with them to the appointment to give their surgeons permission to share information directly with DePuy.

Click here for the recall notice

This notice was shared with hospitals and surgeons regarding the ASR recall.

Dr. Schmalzried discusses the ASR

nospam@example.com (Patricia Walter) — Tue, 16 Mar 2010 09:50:51 -0700

Advice to patients concerning the ASR

I suggest a few points that, I think, everyone can agree to (for any hip, including an ASR):

1. If you have pain or are in any way concerned - go see your surgeon.

2. There are some screening tests. Based on current experience, if blood (or serum) ion levels of Cr and Co are <5ppb, the likelihood a problem with the implant is low. If the level of either is >10ppb, the likelihood of a problem with the implant is increased. In either event, the next step would be an imaging study (ultrasound or MRI) to look for a fluid collection, or a cystic or solid mass - as evidence of an adverse local tissue response.

3. An aspiration of the joint may be appropriate a) to exclude infection as a cause of the joint dysfunction and b) the characteristics of the fluid may help in the differential diagnosis of a problem related to the metal-metal bearing.

I think that the first point is the most important. If you are concerned, go see your surgeon.

Thomas P. Schmalzried, M.D.

The controversy regarding adverse wear in metal-metal bearings by Dr. Gross

nospam@example.com (Patricia Walter) — Tue, 09 Mar 2010 20:52:55 -0700

The controversy regarding adverse wear in metal-metal bearings

Thomas P. Gross , MD 3/5/2010

I have used over 3000 metal bearings in primary total hip and hip resurfacing as well as revision surgery. I have revised 2 for adverse wear 7 years after implantation. I know that most other high volume hip resurfacing surgeons have a similar experience. The revisions were straightforward and the patient enjoyed the same rapid and complete recovery as if she had a primary hip replacement.

Currently less than 5% of my practice involves revision surgery. However, I have revised over 100 metal plastic replacements for excess wear. Furthermore significant wear related damage to the tissues is seen in virtually all metal plastic hip replacement or knee replacement revised for other causes.

A surgical group that has seen a surprisingly large number of wear‐related failures of metal bearing implants has coined the term "pseudotumor" when an inflammatory soft tissue mass is seen around the hip of a metal bearing implant. However, this inflammatory soft tissue reaction to metal wear debris is not much different than the inflammatory reaction that we have seen with plastic wear debris for many years.

All artificial bearing implants give off wear particles. The question is, which type of wear debris is best tolerated by the body? During the last 20 years of joint replacement polyethylene osteolysis (bone destruction caused by plastic wear debris) has been a major problem. But anyone who has revised total joints is also aware that polyethelene debris also is always associated with large amounts of soft tissue reaction around the joint. Polyethelene has been improved, and metal bearings have been developed. Both give off much less wear debris than the old polyethelene implants. The question is which results in less wear related damage? At this point we do not yet have the answer. Adverse wear reaction is a serious problem, but fortunately it is very rare.

Lets put this into perspective. The most common reason resulting in revision of total hip replacements in the US is hip instability (recurrent dislocation). 20% of all hip revisions are done for this reason. This is far more common than adverse wear reaction. Hip instability is a very disabling condition that occurs in 3‐5 % of hip replacements. The rate of instability for large head metal bearings is less than 1/2 %. Larger bearings are the solution for this problem. Large head metal bearings (resurfacing and total hip) are currently the only ones that allow reconstructing the hip in a biomechanically normal fashion to avoid instability. Proponents of plastic and ceramic bearings realize this and have made their bearings thinner recently to allow larger heads to be inserted (32‐36mm). This has made them more stable, but 32‐36mm does not yet approximate normal femoral head sizes in the average female (48mm) and average male (52mm) patients. These larger head (32‐36mm) implants for plastic and ceramic bearings have only been in use for a few years and it is not yet clear if these bearings will break at a higher rate because they are thinner. I would not recommend impact sports on thin plastic and ceramic bearings. Anatomic sizing that matches the patient's own size is only possible with large metal head designs. These are stable and can tolerate repetitive full impact without breaking. Wear rates are not significantly increased by running.

In the last few years we have learned that these rare cases of adverse wear in metal bearings are related to three factors: steep acetabular inclination greater than 55 degrees, small component sizes, certain component designs with an extremely shallow arc of coverage. At this point it is still only a very tiny percentage of patients with cup inclination angles above 55 degrees that have had wear problems. If a patient with an inclination angle above 55 degrees develops symptoms years after surgery, I would first check metal levels and an MRI. If the levels were high or a soft tissue mass developed I would recommend revision. So far this has happened twice in my practice.

More important, however, is prevention of this adverse wear complication. Since this information about cup inclination has become available several years ago we developed and tested a protocol for measuring the inclination by XR during the operation. The paper reporting this technique will be published in CORR this year. Using this technique in every case, I now have had no cups implanted with inclination greater than 55 degrees since 10/ 2007. We expect that this technique will completely eliminate this rare cause of failure in metal bearing hip implants: adverse wear reaction.

Soft Tissue Reactions to Metal-on-Metal Arthroplasty Due Mostly to Increased Bearing Surface Wear

nospam@example.com (Patricia Walter) — Fri, 18 Sep 2009 10:06:18 -0700

Read Complete Article Here By Robert Trace
September 17, 2009

MANCHESTER - Researchers here reported that adverse soft tissue reactions following metal-on-metal hip arthroplasty are typically due to increased wear of the bearing surfaces, and patients with smaller femoral heads may be particularly susceptible to these complications.

In an independent center study, David Langton, FRCS, and colleagues in the Joint Replacement Unit at the University Hospital of North Tees in Stockton, England, reviewed 155 Birmingham Hip resurfacings (BHR, Smith & Nephew) performed between 2002 and 2009 (mean follow-up, 60 months). They also studied 420 articular surface replacements (ASRs) and 75 total hip replacements using ASR XL implants (both DePuy Orthopaedics) with S-ROM stems (DePuy Orthopaedics) with a mean follow-up of 35 months...

...There were 17 failures of this nature in patients with ASR implants (3.5%) and no failures in the BHR group...

...Patients who had adverse reactions to metal debris (ARMD) had a mean femoral size of 45 mm, a mean acetabular angle of 27° and a mean inclination angle of 53°. Among the asymptomatic patients, those numbers were 49 mm, 20° and 48°, respectively...

..."I think we can say that the most important points are that increased wear causes more complications, and all hip resurfacing systems are not the same," Langton said. "Also, we found that it is an issue of joint size and orientation, rather than an issue of gender. And size does matter because men with femoral components less than 49 mm have a 10% incidence of ARMD."

Reference:
Langton D, Jameson S, Joyce T, et al. The incidence of adverse reactions to metal debris (ARMD) following hip resurfacing with the articular surface replacement (ASR) and Birmingham Hip Resurfacing systems (BHR). Presented at the British Orthopaedic Association Annual Congress 2009. Sept. 15-18, 2009. Manchester.

High Metal Ions, Pseudotumors, Metalosis & ALVAL by Patricia Walter 2008

nospam@example.com (Patricia Walter) — Fri, 10 Apr 2009 08:25:50 -0700

Patients and prospective patients are always concerned about the complications that could occur after a hip resurfacing surgery. The typical problems include femur neck fractures, dislocations, loose acetabular cups, improperly positioned acetabular cups, high metal ions, infections, pseudotumors, ALVAL and metalosis.

There has been a lot of discussion among patients on discussion groups about the high metal ion issue and pseudotumors. I am not a doctor or medically trained. I am a Patient Advocate, Hip Resurfacing Patient and Mechanical Engineer. I had the opportunity to attend the Second Annual U.S. Comprehensive Course on Total Hip Resurfacing Arthroplasty October 24–25, 2008 Los Angeles, CA. I listened to discussions about the metal ion issues and pseudotumors. I am going to explain what I learned in simple, non-medical terms since that is all I can do.

As an observer, I learned that the high metal ion issue has occurred in a small number of cases as a post op problem after a hip resurfacing. One of the most likely reasons, according to the experienced surgeons and presenters at the course, was the incorrect placement of the acetabular cup which resulted in additional wear on the bearing surface between the acetabular cup and the femur cap component. The hip resurfacing device is really a metal bearing made of High Carbon Cobalt-Chromium alloys. A bearing is designed to equally spread out the load over the load bearing components. If the components are not aligned properly, then only part of the bearing is loaded resulting in much more wear in that area possibly causing a high metal ion level. It was also explained that women seem to have more problems with high metal ions than men. Perhaps, this is due to the fact that most women use smaller sized hip resurfacing devices which causes more loading on the bearing surfaces than the men's larger sized devices.

When there is an abnormally high metal ion release from misplaced components, it seems to cause the surrounding tissue and bone to react adversely. The surrounding tissue and bone tends to become abnormal. Some doctors call the tissue reaction pseudotumors, AVAL (aseptic lymphocyte dominated vasculitis associated lesion), & others call it metalosis. Whatever name given to the abnormal reaction, it is not good to have this happening around the hip device since it could become loose, pain could result and possibly more severe medical reactions could happen.

There is concern among the hip resurfacing community about the reactions to the very high metal ion issue. At this time, to my understanding, there is not a standardized blood test available. Different labs use different methods and tests. There are not yet any specific guidelines as to what levels are too high for metal ions. There is a lot of research being done, but there are no standards yet.

This makes a surgeon's job to define and solve problems due to high metal ions difficult. Some doctors feel that patients with very high metal ions should have a revision of their hip resurfacing to a ceramic on ceramic THR. They don't want to take chances that even more serious problems could develop due to the high metal ions. Normally, from what I understand, the high metal ions are probably due either to the incorrect position of the acetabular cup causing very high wear on the hip resurfacing bearing device or due to the use of a small hip resurfacing device causing excessive loading on the bearing surfaces. So once again, the learning curve and experience of hip resurfacing surgeons is very important to prospective patients along with proper patient selection. It takes a great deal of experience to consistently place the acetabular cups at the proper angle and to know which smaller patients can successfully receive a hip resurfacing.

That is my layman's explanation of the high metal ion issue. I am posting a number of abstracts below by surgeons attending the Second Annual U.S. Comprehensive Course on Total Hip Resurfacing Arthroplasty October 24–25, 2008 Los Angeles, CA. Their articles will help explain more about the high metal ion issue, the small device issue used in many women and the acetabular cup placement issue.

The Influence of Head Diameter, Clearance, Cup Position, and Head Position on Wear Rates in Metal-on-Metal Resurfacing 2008

nospam@example.com (Patricia Walter) — Fri, 10 Apr 2009 08:21:10 -0700

"The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear"

Presented at the 2nd Annual Total Hip Resurfacing Arthroplasty Course in LA Oct. 2008

By: John Fisher
Co-Authors: Ian Leslie, Sophie Williams, Eileen Ingham, Graham Isaac
Institute of Medical and Biological Engineering
University of Leeds

Background: There are considerable variations in metal ion levels and metallic wear rates in patients with metal on metal resurfacing. In this in vitro study the effect of design variables of head diameter and bearing clearance and patient variables of cup and head position on metal ion levels and wear rates are were investigated. Methods: Hip joint simulator studies were carried out on size 39mm and size 55mm metal on metal resurfacing with the same design. Size 55mm diameter bearings with 110 micrometer diametrical clearance were compared to size 54mm diameter with larger >250 micrometer diametrical clearance. The wear rates of size 39mm bearings with a standard cup position of 45 degrees, were compared to a steep cup position of 60 degrees and to a steep cup position combined with micro separation associated with head offset deficiency.

Results: Initial bedding in wear rates and ion levels were higher with size 39mm bearings compared to size 55mm, but in long term after 15 million cycles there was no difference in the steady state wear rates. Bearings with the larger diametrical clearance had higher initial wear and steady state wear rates at five million cycles. Cup position and head position resulted in much greater increases in wear. For the 39 mm bearings, a 60 degree cup position resulted in a 9 fold increase in wear. A steep cup and microseparation resulted in a 17 fold increase in wear after two million cycles and a 39 fold increase in wear compared to the long term steady state wear rate.

Conclusions: The study confirmed clinical ion level studies of increased wear with larger clearance bearings. The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear. The study also indicates that offset deficiency and microseparation may be responsible for extremely high wear rates and ion levels found in some retrievals and some patients. Further work is needed to investigate effect of different head sizes with steep cups and microseparation and the effect of version.

The Influence of Head Diameter, Clearance, Cup Position, and Head Position on Wear Rates in Metal-on-Metal Resurfacing 2008

nospam@example.com (Patricia Walter) — Fri, 10 Apr 2009 08:21:10 -0700

By: John Fisher
Co-Authors: Ian Leslie, Sophie Williams, Eileen Ingham, Graham Isaac
Institute of Medical and Biological Engineering
University of Leeds

Distribution of Chromium and Cobalt Ions in Various Blood Fractions After Resurfacing Hip Arthroplasty

nospam@example.com (Patricia Walter) — Fri, 29 Aug 2008 10:40:54 -0700

Link: Click here to view complete article

Distribution of Chromium and Cobalt Ions in Various Blood Fractions After Resurfacing Hip Arthroplasty

Leonard R. Walter MBBS(Syd), FRACS, FAOrthA, Ed Marel MBBS(Syd), FRCS Ed (Orth), FRACS, FAOrthA^a, Richard Harbury MBBS(Syd), FRACS, FAOrthA^a and Jenny Wearne RN ^aPeninsula Orthopaedics Research Institute, DEE WHY NSW 2099, Australia

Received 28 November 2006; accepted 7 July 2007

Abstract

The most appropriate blood fraction for the measurement of metal ions in patients with metal-on-metal implants is controversial. We compared chromium (Cr) and cobalt (Co) ion levels in 29 patients after unilateral hip resurfacing with a size 54-mm femoral Birmingham Hip Resurfacing Prosthesis (Smith and Nephew, London, UK). All had well-functioning arthroplasties between 5 and 59 months after implantation. Ion levels were measured in serum, plasma, red cells, and whole blood in each patient. Our results indicate that only very minor amounts of Cr and Co are associated with red blood cells, with most being associated with serum/plasma. Previous studies using corrosion to produce the ion load have showed a predominance of Cr in the red blood cells. They have also shown that the cellular uptake of Cr is an indicator of its valence. This difference in distribution with our results is indirect evidence that the Cr released from wear of this implant is probably in the more benign trivalent form. It also suggests that most of the metal loss from a normally wearing bearing may be from wear rather than corrosion. If blood is to be used to assess rates of wear and systemic ion levels, then serum gives a better reflection of the true levels than red blood cells.

Active Implants Corporation Announces CE Mark Approval for Novel Low Wear,

nospam@example.com (Patricia Walter) — Mon, 28 Jan 2008 17:34:15 -0700

Link http://findarticles.com/p/articles/mi_m0EIN/is_2006_Sept_18/ai_n16729494/

MEMPHIS, Tenn. -- Active Implants Corporation (AIC), a pioneer in pliable orthopaedic implant technology, today announced CE Mark approval for its novel low wear, polymer hip implant which allows the sale of the product throughout Europe.

The AIC Hip Buffer(TM) is a press-fit, low wear polycarbonate polyurethane acetabular cup. This acetabular implant allows for larger femoral head sizes that should enhance joint stability and improve range of motion and shock absorption. The AIC Hip Buffer(TM) has potential applications in both total hip (complete replacement of the joint) and hip resurfacing (replacement of just the surface) surgical procedures, providing a less invasive implant with low wear metal-polymer characteristics. The company will implement a post-approval controlled release of the Hip Buffer(TM).

The AIC Hip Buffer(TM) introduces advanced low wear, pliable materials and innovative implant designs that are less invasive, bone sparing and expected to restore closer to normal joint function. The materials used by AIC are at least 50 times more pliable than all other materials used for this application and can allow for a better and more normal stress transfer to surrounding bone.

"We view this as disruptive technology and are pleased with our progress working closely with leading orthopaedic surgeons on establishing the clinical safety and efficacy of our novel implant technology" said Stephen Bradshaw, President and Chief Executive Officer of AIC. "Following more than a decade of research and development work, the Hip Buffer(TM) marks the beginning of a new generation of resilient implant solutions with a potential broad range of applications in the extremity joints and spine."

About Active Implants Corporation

Active Implants Corporation is a privately-held company formed in 2004 by an experienced team of orthopaedic executives and inventor with vast experience in advanced, pliable materials. AIC owns a robust intellectual property estate of innovative implant solutions and minimally invasive surgery technology with a potential broad range of medical applications. Headquartered in Memphis, Tennessee, the mission of the company is to serve the emerging "Interventional Arthroplasty" market by providing earlier in life orthopaedic implant solutions.

Metal Ion Study Four Year Results

nospam@example.com (Patricia Walter) — Mon, 17 Dec 2007 09:54:07 -0700

Blood and urine metal ion levels in young and active patients after Birmingham hip resurfacing arthroplasty

FOUR-YEAR RESULTS OF A PROSPECTIVE LONGITUDINAL STUDY

J. Daniel, FRCS, Director of Research1; H. Ziaee, BSc(Hons), Biomedical Scientist1; C. Pradhan, FRCS, Staff Orthopaedic Surgeon1; P. B. Pynsent, PhD, Director2; and D. J. W. McMinn, FRCS, Consultant Orthopaedic Surgeon1 1 The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham B15 3DP, UK. 2 Research and Teaching Centre, Royal Orthopaedic Hospital, Northfield, Birmingham B31 2AP, UK.

READ COMPLETE STUDY

This is a longitudinal study of the daily urinary output and the concentrations in whole blood of cobalt and chromium in patients with metal-on-metal resurfacings over a period of four years.

Twelve-hour urine collections and whole blood specimens were collected before and periodically after a Birmingham hip resurfacing in 26 patients. All ion analyses were carried out using a high-resolution inductively-coupled plasma mass spectrometer. Clinical and radiological assessment, hip function scoring and activity level assessment revealed excellent hip function.

There was a significant early increase in urinary metal output, reaching a peak at six months for cobalt and one year for chromium post-operatively. There was thereafter a steady decrease in the median urinary output of cobalt over the following three years, although the differences are not statistically significant. The mean whole blood levels of cobalt and chromium also showed a significant increase between the pre-operative and one-year post-operative periods. The blood levels then decreased to a lower level at four years, compared with the one-year levels. This late reduction was statistically significant for chromium but not for cobalt.

The effects of systemic metal ion exposure in patients with metal-on-metal resurfacing arthroplasties continue to be a matter of concern. The levels in this study provide a baseline against which the in vivo wear performance of newer bearings can be compared.