Hip Resurfacing Issues

I received an email from Tom Phelan from the McMinn Center announcing the press release below by Mr. McMinn.  This can also be found on Mr. McMinn's website
http://www.mcminncentre.co.uk/news-archive.html

1st February 2012
Metal-on-Metal Implants - Addressing the Negative Press

We have been receiving phone calls following recent press reports on failed metal-on-metal hip implants. We understand these sensationalist stories may cause anxiety among some patients. However, we would like to reassure our patients that these reports mostly concern failures with the DePuy ASR and the DePuy ASR XL, not the Birmingham Hip Resurfacing (BHR).

Many press reports imply these failures relate to all metal-on-metal hip resurfacings. A patient featured in a recent Daily Mail article, like many others, had a failed ASR. A critical point, omitted from the print version of the Daily Mail, can be found in the full on line version. As well as her ASR, the patient had a BHR on her other hip. She comments, "I've never had a minute's trouble from the Birmingham hip – if only I'd had it on both sides."

High failure rates with the ASR and ASR XL have been widely documented. Both devices have now been withdrawn from the market. Research indicates the side effects, such as muscle damage, are specific to the ASR and do not apply to the BHR which is a very different device.

Earlier this week, the MHRA (Medicines and Healthcare products Regulatory Agency) issued another statement about metal-on-metal hips, in which they say, "On the evidence currently available the majority of patients implanted with metal-on-metal hip replacements are at low risk of developing any serious problems.”

In addition to the MHRA’s guidance, we wish to emphasise that Mr McMinn’s results with the BHR show a 97% survival in men and women of all ages at 14.5 years. Furthermore, excellent results with the BHR have been documented in National Joint Registers from around the world.

Sadly, these ASR failures come as no surprise. Mr McMinn has been warning about the device since it went to market in 2003. You can see Mr McMinn’s argument against the ASR here http://www.mcminncentre.co.uk/research-lectures-debate.html. Furthermore, The McMinn Centre has put together several resources which address patients’ concerns and the differences between the ASR and BHR designs. These resources are as follows:

• The McMinn Research Team's detailed response to list of questions on metal-metal implants & metal ions provided by hip resurfacing users here
• The McMinn Centre’s response to a Channel 4 documentary on metal-metal hip replacements here  http://www.mcminncentre.co.uk/metal-ions-questions-answers.html
• An interview with a patient who has now had his McMinn metal-metal hip resurfacing for 20 years here

If you do have any concerns, please call The McMinn Centre on 0121 455 0411.

Larger cups and optimal positioning produced lowest ion levels and wear

In a review of 585 blood serum evaluations following hip resurfacing, only femoral size and cup inclination were found to have an effect on ion levels, according a study by orthopedic investigators.

The findings were presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons.

David J. Langton, MRCS, and his colleagues also found that the size of the coverage angle of the acetabular component contributed significantly to its tolerance of suboptimal positioning.

"Larger joints, it must be emphasized, tolerated suboptimal cup position," he said. "This must be taken into account in all analyses."

Inverse relationships

Using routinely obtained blood serum metal ion levels from patients under the care of the two senior authors of the paper being presented - both highly experienced hip resurfacing surgeons - metal ion results were analyzed regarding their relationship to femoral and acetabular component size and orientation, UCLA activity score, age, time post surgery and postoperative femoral head/neck ratios.

Langton reported an inverse relationship between metal ion levels and femoral size. A smaller acetabular coverage arc was associated with higher metal ion levels.

Another significant inverse correlation was noted by Langton between metal ion levels and contact patch to rim (CPR) distance. CPR is a measurement that relates the position of the articular contact patch with the patient in standing position to the cup rim. According to the abstract, CPR less than 5 mm is associated with a 50% chance of ion levels greater than 30 mg/L.

Words of warning

Langton warned the audience, "To increase metal ion levels as quickly as possible, use as small a bearing diameter as possible, use a cup with the smallest coverage arc, and combine very high anteversion with high inclination."
He concluded, "Cups placed with angles between 40° and 50° inclination and 10° to 20° anteversion have the lowest ion levels and the lowest rates of volumetric wear."

Reference:

Langton D, Jameson S, Joyce T, et al. A review of 585 serum metal ion results post hip resurfacing: cup design and position is critical. Paper 006. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons. March 9-13. New Orleans.

Langton has received research or institutional support from DePuy, a Johnson & Johnson Company, DJ Orthopaedics; he has also received miscellaneous non-income support (e.g., equipment or services) from DePuy, a Johnson & Johnson Company.

ALVAL, PSEUDOTUMOUR, HYPERSENSITIVITY … WHATEVER YOU CALL IT, IT’S A REVISION TO THR

Having visited this site numerous times over the last few years, I thought it was time that I shared my experience with other past and future hip patients. I have recently undergone revision of my ASR to a THR because of a reaction to the metal on metal bearing. I know this issue is in the spotlight of the orthopedic hip community internationally just now as more patients emerge at the 3-5 year post-op mark with unique reactions.

I am a female and was diagnosed with osteoarthritis in my left hip when I was 33 years old (I am now 42). At the time I was an amateur triathlete competing at local events but struggling to meet training goals because of pain. Once I had the diagnosis at least I knew the cause, and also knew that heavy use of anti-inflammatory eased the symptoms. Ultimately however, whether I was resting or training the pain continued. In addition to the OA, I had some bone spurs and when I was 35 I agreed to have the spurs removed ("femoro-acetabular debridement") in the hope of alleviating impingement and delaying serious OA. My first major surgery.

After 12 months it was apparent that the debridement was unsuccessful and in fact the OA had worsened to the point where I was ready for a resurfacing. My second major surgery.

The resurfacing was wonderful in that it got me back to pain-free life; walking, sitting, sleeping, cycling. In fact I became a strong cyclist, riding over 100 km every Friday morning at a strong pace in our local peloton, and going on a number of international cycle-touring holidays. I kept trying to run – that was my ultimate dream. Once or twice over the years I managed to belt out 5 or 6 km, but usually I would start experiencing enough discomfort to make me walk after just a few hundred meters. I was still taking anti-inflammatory off and on for general aching in my left leg. Range of motion was definitely improved, although not to the point where I could, for example, sit with my legs crossed. I saw my orthopedic specialist quite regularly – both professionally at his clinic for follow-ups, and also socially as he is also a keen cyclist and we spent many hours chatting whilst spinning along at 30+ kph. My x-rays looked perfect.

At about the 3.5 year mark, I started to notice weakening in my hip flexor. I was dropping off the back of the peloton and couldn’t do anything to get stronger. I saw my physiotherapist and concentrated on strengthening the surrounding muscles for six weeks before confessing to my doctor that I was really facing problems. The only anomaly that was apparent on x-ray was re-growth of bony spurs, which we discussed removing.

Before another major surgery however, we decided to run a battery of tests … bone scan, bloods, MRI, CT, ultrasound. All these tests were inconclusive, except for the ultrasound which showed some fluid in the groin. It also showed that the tip of one of the screws remaining from my resurfacing procedure ("trochanteric flip") was protruding into my groin so we agreed to first try a less drastic approach of removing the screws. My third surgery.

I was only on a crutch for a few days, but the swelling and limping continued for months. My range of motion improved almost miraculously – it felt like a brick had been removed from my groin and I was sure this was a success! By three months though I still had a strange half-golf-ball sized lump over the trochanteric wound site and I still had pain. Back to the doctor, where alarm bells started ringing again. He excised the lump that same day … expecting to drain fluid but in fact finding dead tissue. My thigh was finally flat again but not for long … by the next day the lump was back.

Infection, cancer and loosening were all ruled out. A metal-ion test was requested of the pathologist, but seemingly there was nothing apparent. Things were not looking good but a definitive diagnosis was difficult.

Around this time there were a couple of European conferences which my doctor was attending, dealing specifically with hip resurfacing. He was able to talk to the presenting pathologist as well as a colleague of his who represented the European Advisory Committee for adverse reaction to MoM implants. Now the diagnosis was conclusive … classic symptoms and the only option was revision to a ceramic THR. Surgery number four.

(It turns out that the fluid – actually necrotic tissue – had drained from my hip joint and down through the holes left by removal of the screws to present on my outer thigh. An incredibly unusual scenario! I think if this hadn’t happened our next step would have been needle aspiration of the hip joint to get a sample of the fluid/tissue. I have a whole new appreciation for ultrasound.)

I am now at six week’s post-op. Again the surgery went perfectly (6.5 hours) and the x-rays look great. Definitely it has been the most difficult of all the procedures I have had, with a slower recovery. I am walking on one crutch, but thankfully can get in the pool and swim with the squad using a pull-buoy instead of kicking. I’m still taking pain meds and imagine I will need them and the crutch for another couple of weeks. For a semi-revision surgery though I think I am doing okay; I am at work and am planning on joining a gym this weekend to start getting some strength back in my legs. In a couple of months I will get back on the bike (maybe not in the peloton) and there is a surf-ski endurance race at the end of the year that I would like to train for.

Whilst I breezed through the previous surgeries I found this one very traumatic emotionally as well as physically. Over the months I have spent loads of time surfing the web for stories and information and experiences. I thought it was time to share mine. If anyone has been through this I would love to hear how your recovery is; and if anyone is facing this I would be absolutely happy to talk about it more.

Paula

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.

New Data Reinforces the Proven Safety and Effectiveness of the BIRMINGHAM HIP Resurfacing System

80-percent of US surgeons choose the BHR hip as it outperforms all other metal-on-metal resurfacing devices

MEMPHIS, Tenn., May 3 /PRNewswire-FirstCall/ -- Recent new data(1) presented at this year's American Academy of Orthopaedic Surgeons (AAOS) annual meeting reinforces the BIRMINGHAM HIP™ Resurfacing (BHR) System as a safe and effective hip resurfacing device. The multi-site study, performed by orthopedic surgeons practicing at nine Canadian academic centers, showed that three years after surgery, 99.91% of their 3,400 hip resurfacing patients experienced no implant failure due to metal wear debris. The BHR Hip was the most used resurfacing device in this study.

This week, the Hospital for Special Surgery (HSS) in New York City will be holding a medical education course titled "Total Hip: Replacement and Resurfacing" on May 7 and 8 for leading hip surgery specialists from across the U.S. Chairing the course will be Edwin Su, MD, of the Hospital for Special Surgery, and the teaching faculty will include pioneering British surgeon Derek McMinn, MD, inventor of the BHR hip.

During a press conference and Q&A webcast on Thursday, May 6, at 3 p.m. US EDT, 8 p.m. GMT, Joseph M. DeVivo, president of Smith & Nephew Orthopaedics (NYSE: SNN, LSE: SN), the maker of the BHR Hip, will be joined by Dr. Su and Mr. McMinn, as well as Scott Marwin, MD, an orthopedic surgeon with New York University's Hospital for Joint Diseases. The panel will review current data confirming the safety and effectiveness of hip resurfacing and the BHR Hip. Smith & Nephew Orthopaedics will host the call, and additional details are at the bottom of this release.

The new study recently presented at the AAOS meeting aligns with previously released BHR Hip data from other prestigious sources and further addresses the metal wear debris concerns raised about metal-on-metal hip implants.  The BHR Hip's track record for longevity remains unchallenged in the literature, as well. These sources include:

• The Journal of Bone and Joint Surgery published in January of this year a study tracking 155 consecutive BHR patients over three years. The data showed no revisions of BHR Hips due to metal wear, but patients who received a competing metal-on-metal resurfacing device were revised within three years of surgery at a rate of 3.4-percent due to adverse tissue reactions.(2)
• The Australian Orthopaedic Association's 2008 National Joint Replacement Registry, a record of nearly every hip implanted in that country over the previous 10 years, tracked 6,773 BHR Hips and found that less than one-third of one-percent may have been revised due to the patient's reaction to the metal component.(3)  
• The Australian Registry hip resurfacing data for 2009, 70-percent of which comes from BHR Hip procedures, indicates that for men under age 65, hip resurfacing performs at the same or a better rate than total hip replacement. This registry also shows that the BHR Hip remains successful in 95-percent of cases eight years after surgery, whereas no other implant performs better than 94.7-percent just five years after surgery.(4)
• Great Britain's Oswestry Outcomes Centre's patient registry,  which tracked 5,000 BHR Hips implanted by 148 different surgeons in 37 countries over 10 years (1998-2008), reports that the BHR Hip remains successful in 95.4-percent of all patient segments 10 years after surgery. This registry also reported that 98.6-percent of patients were "pleased" or "extremely satisfied" with their BHR Hip implants 10 years after their resurfacing procedure.(5)
• Mr. McMinn's clinical data, based on 3,095 hip resurfacing patients implanted between 1997 and 2009, shows that more than 12 years after surgery, the BHR hip remains successful in 99-percent of men aged 60 and over, and 97-percent for men under age 60.

"The BHR Hip's outcomes are remarkable when compared to other resurfacing devices," said Dr. Marwin. "The depth and consistency of the data collected globally shows the BHR Hip is truly different."

"For the right patients in my practice, hip resurfacing has proven to be an excellent choice," said Dr. Su. "They have extremely high levels of satisfaction after returning to their regular lifestyle."

To explain the patient advantages seen consistently in the literature, surgeons indicate the key differences between the BHR Hip and other resurfacing devices are its metal composition, its design geometry and its surgical instrumentation.

The BHR Hip has a unique metallurgy heritage which goes back more than 30 years and includes a first-generation metal-on-metal resurfacing process which contributes to long-term survivorship of BHR Hip recipients.

Additionally, the BHR Hip's design geometry replicates the natural hip's ability to pull the body's own joint fluids into the ball and socket interface, which is believed to be another source of its best-in-class performance.

Of particular importance during hip resurfacing surgery is the correct positioning of the acetabular cup, or hip socket. When this component is not properly aligned, studies show that metal wear can accelerate and resurfacing devices can fail before their time.  Surgeons believe that the instrument used to implant the BHR Hip is simpler and more accurate than other devices' instruments, and may contribute to its success.

"Just like the lubricating barrier in a healthy hip, there is a natural fluid layer between the femoral head and the cup that the two metal surfaces glide across during physical activity," said Mr. McMinn. "If the surgeon malpositions the acetabular cup causing edge loading, the lubrication is lost. It's equivalent to running a car engine without lubrication oil. High wear will occur, resulting in premature failure. Overall, it is a combination of the metal composition, the design and the quality of the surgical technique that makes the BHR Hip the safest resurfacing implant on the market."

"The bottom line is that the BHR Hip is not like other metal-on-metal hip implants," said DeVivo. "Not only does it have the longest track record of any resurfacing device, but the most esteemed medical literature shows it outlasts other implants. It's in a class all its own – it's safe and effective, and is the best choice for active patients."



Footnotes

(1) Beaule PE, Smith FC, Powell JN et al. A Survey on the Incidence of Pseudotumours with MOM Hip Resurfacings in Canadian Academic Centres. Podium presentation # 665. Proceedings of the American Academy of Orthopaedic Surgeons Annual Meeting, New Orleans LA. 2010

(2) Langton DJ, Jameson SS, Joyce TJ, Hallab NJ, Natu S, Nargol AVF.  Early failure of metal-on-metal bearings in hip resurfacing and large-diameter total hip replacement, A CONSEQUENCE OF EXCESS WEAR. J Bone Joint Surg Br. 2010; 92-B: 38-46

(3) Table HT 46. Australian Orthopaedic Association National Joint Replacement Registry Annual Report. Adelaide: AOA; 2008.

(4) Table HT 46. Australian Orthopaedic Association National Joint Replacement Registry Annual Report. Adelaide: AOA; 2009.

(5) Robinson E, Richardson JB, Khan M. MINIMUM 10 YEAR OUTCOME OF BIRMINGHAM HIP RESURFACING (BHR), A REVIEW OF 518 CASES FROM AN INTERNATIONAL REGISTER. Oswestry outcome centre, Oswestry, UK.

About Us

Smith & Nephew is a global medical technology business, specialising in Orthopaedics, including Reconstruction, Trauma and Clinical Therapies; Endoscopy and Advanced Wound Management.  Smith & Nephew is a global leader in arthroscopy and advanced wound management and is one of the leading global orthopaedics companies.

Smith & Nephew is dedicated to helping improve people's lives.  The Company prides itself on the strength of its relationships with its surgeons and professional healthcare customers, with whom its name is synonymous with high standards of performance, innovation and trust.  The Company operates in 32 countries around the world.  Annual sales in 2009 were nearly $3.8 billion.

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This press release contains certain "forward-looking statements" within the meaning of the US Private Securities Litigation Reform Act of 1995.  In particular, statements regarding expected revenue growth and trading margins discussed under "Outlook" are forward-looking statements as are discussions of our product pipeline.  These statements, as well as the phrases "aim", "plan", "intend", "anticipate", "well-placed", "believe", "estimate", "expect", "target", "consider" and similar expressions, are generally intended to identify forward-looking statements.  Such forward-looking statements involve known and unknown risks, uncertainties and other important factors (including, but not limited to, the outcome of litigation, claims and regulatory approvals) that could cause the actual results, performance or achievements of Smith & Nephew, or industry results, to differ materially from any future results, performance or achievements expressed or implied by such forward-looking statements.  Please refer to the documents that Smith & Nephew has filed with the U.S. Securities and Exchange Commission under the U.S. Securities Exchange Act of 1934, as amended, including Smith & Nephew's most recent annual report on Form 20F, for a discussion of certain of these factors.

All forward-looking statements in this press release are based on information available to Smith & Nephew as of the date hereof.  All written or oral forward-looking statements attributable to Smith & Nephew or any person acting on behalf of Smith & Nephew are expressly qualified in their entirety by the foregoing.  Smith & Nephew does not undertake any obligation to update or revise any forward-looking statement contained herein to reflect any change in Smith & Nephew's expectation with regard thereto or any change in events, conditions or circumstances on which any such statement is based.

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A Modified Posterior Approach Preserves Femoral Head Oxgenation During Hip Resurfacing 2010

Steffen RT, De Smet KA, Murray DW, Gill HS  2010 Mar 22

Original Link  http://www.ncbi.nlm.nih.gov/pubmed/20334994?dopt=AbstractPlus

Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.

In 11 patients, the oxygenation was measured in the superolateral quadrant of the femoral head during resurfacing with a modified posterior approach, designed to preserve the blood supply, using a gas-sensitive electrode. These were compared with measures from 10 patients in whom the standard posterior approach was used. The modified approach patients maintained a significantly (P < .005) higher amount of relative oxygenation after the approach, 78% (standard deviation [SD], 45%) vs 38% (SD, 26%), and acetabular component implantation, 74% (SD, 56%) vs 20% (SD, 28%). The modified posterior approach, unlike the standard extended approach, does not significantly compromise the blood supply to the head; and we recommend this approach be considered for hip resurfacing.

A Consensus From The Advanced Hip Resurfacing Course, Ghent, June 2009 About Metal-on Metal Hip Resurfacing

K. De Smet, MD, Orthopaedic Surgeon¹; P. A. Campbell, PhD, Associate Professor²; and H. S. Gill, DPhil, University Lecturer in Orthopaedic Mechanics^{3 1} ANCA Medical Center (AMC-Ghent), Krijgslaan 181, 9000 Ghent, Belgium.
² UCLA/Orthopaedic Hospital, 2400 South Flower Street, Los Angeles, California 90007, USA.
³ Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Oxford OX3 7LD, UK.

Abstract

We report the consensus of surgical opinions of an international faculty of expert metal-on-metal hip resurfacing surgeons, with a combined experience of over 18,000 cases, covering required experience, indications, surgical technique, rehabilitation and the management of problematic cases.

Introduction

The last decade has seen an increased use of metal-on-metal hip resurfacing arthroplasty as an alternative to contemporary total hip replacement (THR), especially for patients who wish to participate in high-demand activities. Metal-on-metal bearings are also being used more often for THR. In June 2009, the third Advanced Resurfacing Course was held in Ghent, with a faculty that included 21 orthopaedic surgeons whose combined experience included over 18,000 metal-on-metal hip resurfacing arthroplasties. As the meeting served to bring together surgeons, highly experienced in hip resurfacing, from Australia, Europe and the Americas, the opportunity was taken to establish consensus views on issues of required experience, indications, surgical technique and rehabilitation. The aim of this annotation is to disseminate these consensus findings in order to help surgeons who are considering metal-on-metal bearings for both resurfacing and conventional THR. The findings are presented as a majority opinion, with the percentage of the faculty in agreement given in parentheses.

Required experience

The use of metal-on-metal bearings for THR and resurfacing presents a greater technical challenge than that of conventional metal-on-polyethylene bearings. The consensus (81%) was that an orthopaedic surgeon should have a minimum experience of 200 conventional THRs before starting to use a metal-on-metal hip resurfacing arthroplasty. Opinion varied on the number of these operations needed to overcome the learning curve, and ranged from 20 (36%), to 50 (28%) and more than 50 (30%).

Indications

The overall view (100%) was that the ideal candidate for an metal-on-metal hip resurfacing arthroplasty is a relatively young man with normal anatomy and primary osteoarthritis. Being female was not, by itself, a contra-indication (89%), but use of a small femoral head (< 46 mm) was contra-indicated (70%). Being female and wanting to have children was a contra-indication (66%), as was being female and having a metal allergy (70%). Grossly abnormal anatomy, regardless of gender, was also agreed to be a contra-indication (83%). There was considerable debate about bone quality, the general view being that 'good' femoral bone is a prerequisite, but no agreement was reached on a working definition of acceptable quality.

Surgical technique

The majority opinion (56%) was that the best type of femoral placement guide is that which encircles the femoral neck. There was general agreement (63%) that the current acetabular placement jigs are inadequate. The overall preference (78%) was for cementing the femoral component with a thin cement mantle with fixation holes drilled in the femoral bone, use of pulsed lavage, and reduction of the hip in less than eight minutes from the start of mixing the cement.

Rehabilitation

Full weight-bearing can be allowed on the first post-operative day (73%) and patients should use crutches for as long as needed (57%). Six weeks is the optimal time to return to normal non-sporting daily activities (44%), and six months for returning to impact sports such as running or tennis (61%).

Managing problematic cases

It was difficult to achieve a consensus on this topic, and only the broad recommendations of the discussion are reported. It was generally agreed that these patients need to be followed up and those with symptoms investigated. There was no agreement on the diagnostic value of measurements of metal ions, but it was felt that  'high' concentrations of systematic metal ions indicated a problem with the articulation. Cross-sectional imaging and plain radiographs are required for the investigation of a symptomatic metal-on-metal bearing.

It is hoped that these consensus opinions will prove useful to orthopaedic surgeons and will lead to improved outcomes after surgery for hip replacement.

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.

I have to start by saying that I have never had any issues with the ASR devise at all. I was very surprised about 6 months ago when the issue of ASR withdrawal first surfaced. There is no doubt that the safety margin for the ASR is lower than other resurfacing systems like the BHR due to a 'low arc of cover'- described by Dr. Desmet. This is because the rim of the cup has become 'non -articular' to accommodate the cup holder. Hence the failure rate is higher than the BHR.

The cups coming loose is certainly not true as I have implanted ASR cups in the most complex of cases. I am 100% confident that it is a technical issue.

It has proven to be an excellent tool in my hands and in dysplasia patients ( CROWE 3)- the s-rom with a ASR cup combination that is hard to beat.

The ASR reamers are very poor and not matched to the ASR cups. I have routinely used BHR or equivalent reamers for the ASR cups for 3 yrs since the time noticed the mismatch between the reamers and cup size for the ASR

The ASR has been excellent tool to provide an anatomical metal on metal articulation in small patients. I am very confident that it will work well if installed correctly. I will surely miss the ASR cup for small made patients if it is withdrawn completely.

with best regards
vijay bose
chennai

Knowing the cause of resurfacing failure can ensure successful conversion to THR by Edwin Su, MD
The shell can be retained in cases involving femoral neck fracture, femoral loosening or impingement.

Read Complete Article by clicking here

March 2010

Causes of failure

"The cause of failure must be carefully assessed prior to the conversion surgery in order to ensure an optimal THR outcome," Su said. He noted that femoral neck fracture is the primary cause of short-term failure in resurfacing procedures. He theorized that the rate of these fractures could be reduced with improved surgical techniques, careful patient selection and preoperative evaluation of bone quality. Inadequate acetabular fixation or the so-called "slipped cup" is another cause of early failure, which may also be related to surgical technique.

"The greatest cause of a mid-term failure is femoral component loosening and osteonecrosis probably plays a role in this," Su said. "I think that component malposition is going to play a large role in these mid-term failures as well." He noted that mid-term investigations of patients with acetabular component malpositioning revealed painful metal reactivity requiring revision.

Other causes of failure include metal hypersensitivity and unexplained pain due to impingement, undetected stress fractures or pseudotumors...

...Shell retention or full revision?

In planning conversion procedures, surgeons have the option of retaining the shell from the hip resurfacing.

"I think this is acceptable for a well-positioned, well-fixed and undamaged shell," Su said. "It is applicable in situations such as, a femoral neck fracture and in a femoral loosening...

..."A full revision is necessary when there is component malposition of chronic duration because there will be damage to the metal components," Su said. "It is also best when there is a question of metal hypersensitivity."

Reference:

• Su E. Surface replacement conversion: Assuring an optimal THR outcome. Paper #44. Presented at the 26th Annual Current Concepts in Joint Replacement Winter Meeting. Dec. 9-12, 2009. Orlando, Fla.
• Edwin P. Su, MD, can be reached at Hospital for Special Surgery, 535 East 70th Street, New York, New York 10021; 212-606-1128;