HR Devices

Smith & Nephew Press Conference about the Safety and Effectiveness of Hip Resurfacing with the BHR -
Birmingham Hip Resurfacing Device

Review by Patricia Walter

May 6, 2010

Introduction: Joseph M. DeVivo, President of Smith & Nephew Orthopaedics

Joseph M. DeVivo, President of Smith & Nephew Orthopaedics (NYSE: SNN, LSE: SN), the maker of the BHR Hip introduced the press conference and discussed the safety and effectiveness of the BHR.  He explained that over 125,000 patients worldwide have received a BHR since 1998. The BHR and the issue of metal sensitivity in patients with MOM (metal on metal) implants will be discussed. The purpose of this event is to deliver specific facts about the BHR and its unrivaled track record of success for active patients around the world.

Mr. DeVivo explained that information about hip resurfacing presented at the 2010 American Academy of Orthopedic Surgeons will be discussed.  Recently, there has been negative information in the press about metal on metal devices which includes hip resurfacing devices like the BHR.  The press has taken the failures of a few to cast doubts about all hip resurfacing.   It has omitted the successes of hip resurfacing and that 7 out of 10 surgeons performing hip resurfacing choose the BHR.  Smith & Nephew feel the BHR is a safe and effective device providing successful hip resurfacing for patients worldwide.

Derek McMinn, MD, British surgeon and inventor of the BHR

Derek McMinn, MD, pioneering British surgeon and inventor of the BHR hip explained that the BHR has been proven successful by peer review data and his own clinical data. There are four main pieces of evidence that show the success of the BHR:

1.   The Australian Orthopaedic Association's National Joint Replacement Registry - tracked every hip resurfacing since 1998.  Less than 1/3 of 1 percent of hip resurfacing failures are caused by an adverse tissue reaction.

2. In a 9 center Canadian study presented at the recent 2010 AAOS, 3 resurfacing patients out of 3400, less than 1/10 of 1 percent, experienced a tissue reaction.

3. Long Term data, from the Owestry outcome center, tracked 5000 BHR patients and now 518 BHR patients at 10 years of follow up. The study was carried out by 18 surgeons in 16 different countries. There was a 95% success rate at 10 years.

4.  Mr. McMinn’s own clinical data started in 1997.  He performed 3095 BHRs until end of 2009.  At 12 years follow up, he has a 96% survivorship.

Therefore, according to McMinn, those 4 pieces of data from a large number of surgeons and his own clinical experience shows the BHR works.  There have been adverse reactions reported in all of the studies, but these numbers are incredibly small. However, since MOM resurfacing has been going on in UK since 1991, when he did his first resurfacings, there have been a number of adverse reactions reported. One study from Oxford has over 30 presentations or publications of pseudotumors.  In 2008, one percent of their patients were affected by this condition. Mr. McMinn explained that we need to examine what has happened in Oxford. They presented and published 610 BHRs in 2008. Those patients were operated on by 7 consultants and 30 trainees resulting in a large input from inexperienced surgeons. We know, explained McMinn, from a presentation from the last academy meeting that they have reported on poor surgery. The inclination angle of the cup should be 40 degrees; however, the Oxford pseudotumor group reported angles from 10.1 to 80.6 degrees.  I need to stress, the high inclination angles up to 80.6 angles are completely unacceptable. Every BHR, Metal on Metal, Ceramic on Ceramic and metal on poly device will fail with that type of poor surgery.  

McMinn explains that the adverse reactions for hip resurfacing are reported from 2 categories:

1. Poor results from well established BHRs put in badly causing edge loading, high metal wear and an adverse tissue reaction to lots of debris.

2. Poor results from implants that don’t work. The  4^th generation devices such as the Durom and ASR devices have both been associated with much higher failure rates than the BHR both on individual surgeon reports and Australian national registries. The adverse tissue reactions to the ASR are particularly prevalent. The UK reports around 7% revision rate for ASR resurfacing.  ASR THR mom failures are also double than other devices.  So the UK regulatory bodies are faced with reports of devices that are poor and adverse tissue reactions by well established devices put in badly.

Edwin Su, MD, of the Hospital for Special Surgery

Edwin Su, MD, of the Hospital for Special Surgery, agreed about the importance of hip resurfacing in the lives of patients.    After training with Mr. McMinn and Dr. Amstutz, he has completed over 1300 hip resurfacings with majority being BHRs.  I can say with authority that this procedure can be a life restoring event for the patients. Metal on Metal hip resurfacing done with precise technique and a well designed implant can work.  In appropriate patients, hip resurfacing can achieve nothing short of miraculous life changing results.  Hip resurfacing allows patients to return to active pain free lives. Certain patient types do better with resurfacing than others.  Good solid bone stock means you will do well.  Poor bone stock means there is an elevated risk of a femoral neck fracture. This is common knowledge    Patients under age 65 have best bone stock.  92.7% of all resurfacings are in patients under 65.  Patient selection is very important.  The data shows men do better than women.  Women require smaller components and are more difficult to align during surgery.  Also women’s bones are less dense, so some women are not ideal candidates for hip resurfacing. Australian shows 80% resurfacings are in men.  Resurfacing works better in men than women. Women of child bearing years are not recommend to have hip resurfacing.

Dr. Su explained about the issue of Implant alignment.  If the components are misaligned, there will be an increased risk of metal wear because the surfaces will not be properly lubricated during regular physical activity. There is a resulting risk of adverse tissue reactions and possible revision surgery.  Although this is true for most hip replacement surgery, it is especially true for resurfacing since the implants are less forgiving due to their precise manufacturing.  This rate of adverse tissue reactions is extremely rare in resurfacing and less than ½ of 1 percent.

The literature, explained Dr. Su, shows experienced surgeons who have undergone appropriate training, can place a hip resurfacing device correctly.  A surgeon not doing them on a regular basis has a greater chance of not achieving optimal results. It’s that simple explained Dr. Su.   This is true in any surgery in any specialty. While some implants perform better than others, good outcomes with hip resurfacing most often are achieved by experienced surgeons who have received excellent training and are careful in patient selection.  Dr. Su has offered hip resurfacing since 2006 and has seen spectacular results since then.

Scott Marwin, MD, an orthopedic surgeon with New York University's Hospital for Joint Diseases

Dr.  Marwin explained that the use of the BHR, after 12 years use worldwide and 4 years use in the states, remains an exciting option for some patients.  It has never been suggested for all hip replacement surgery.  Fewer than 10% of all patients are candidates.  Fundamentally, it is a bone conserving procedure and saves a significant amount of healthy bone.  Preservation of the basic structure of femur retains the natural size and angles of the joint and reduces any possibility of leg length discrepancy after surgery.  Also patients’ soft tissue doesn’t have to adjust to a different set of shapes and kinematics that comes with a THR. Many patients forget which side has the BHR implant.  Hip resurfacing also retains the patient’s anatomy which decreases the possibility of a dislocation. In a THR, the long metal neck can act like a lever on the edge of the metal cup and dislocate the ball out of the socket.   The natural femoral neck retained during hip resurfacing means incidence of dislocation is extremely rare.  If a resurfacing patient needs a revision, they can receive a matching THR component to match the existing cup.  Hip resurfacing reduces wear and leads to a longer life for the implant as compared to a THR.  Dr. Marwin has implanted more than 750 hip resurfacing devices and can see what they can do for the active patient.

 

Summary by Joseph M. DeVivo

 The BHR is different than other MOM devices on the market that are not performing up to standard. The BHR outperforms the gold standard for THRs in the core patient age group. Hip resurfacing gives patients their active life style back.  BHR preserves so much healthy bone that it feels like a normal hip. More information can be found a www.hipsresurfacing.com

Question and Answers from Audience

Question:  Terry Stanton, AAOS.  Concerning the medical device alert in Britain - is it warranted and correctly crafted?

Answer: Dr. Su - It casts a general concern over MOM usage, but does not speak specifically to the BHR.  BHR has its own clinical data and has not produced the type of concern other MOM device have.  It stands on its own according to worldwide sources.

Q: Surgeon inexperience and poor technique – more globally in the US, what factor will it play?

A:  Dr. Su - Where the BHR is concerned, as part of the FDA approval, it has mandated a very high level of training.  Every surgeon is trained to same protocol.

Q: Canadian Study presented in New Orleans – follow up was 3 years. Comment on how solid the evidence is since the follow up is shorter.

A.  Mr. McMinn - Important to look at what happens in first 3 years in hands of a new group of surgeons to hip resurfacing.  The Oxford Group is reporting adverse reactions to metal debris in the early years. It is highly significant how a new group of trained surgeons get on.  The fact that there are an incredibly low number of incidents of adverse reactions in a 9 center study with over 3000 patients speaks volumes for the devices and training of the surgeons.  The longer term results are more important. The Australian registry has over 8000 people with an incredible low incidence of adverse reactions with survivorship at  95% for BHR at 8 years.  The Oswestry registry with 518 patients at 10 years, shows a  95.4% implant survivorship.  Phenomenally good results.  In my own group, adverse reactions have occurred in 0.3% of my whole group.  Out of 3095 BHR patients thru 2009, there were 10 adverse reactions.  Unlike the Oxford Group, all the revisions have been fine. None were associated with soft tissue destruction.  These were in the main, fluid collections requiring a bearing change to solve the problem. The patient made a totally uncomplicated recovery.  I saw adverse reactions much later.  Oxford was showing them 2 or 3 years after surgery. 

Q. Metal sensivity and pseudotumros are always curious problems.  In terms of devices, is there is less metal release in different devices?

A. Mr. McMinn - It is very clear who gets the pseudotumors. The retrievals from the Oxford Group show pseudotumors were associated with aged wear of the acetabular cup.  With normal lubrication and normal wear, there are no pseudotumors.  Clearly,  if you want a MOM device to fail,  implant it badly or design it badly so you get age loading and age wear which results in a high metal volume of debris early on.

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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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

The status of DePuy Orthopaedics’ ASR platform as Feb. 2010

Last fall of 2009, DePuy decided to discontinue ASR® XL Acetabular Head System and DePuy ASR® Hip Resurfacing Platform (not available in the U.S.) worldwide. As a result of declining demand for the ASR platform and other market factors, DePuy is in the process of phasing out this platform to focus on the development of next generation hip replacement and resurfacing technologies that best meet the needs of surgeons and patients.

DePuy wants to assure patients who have been treated with a device from the ASR platform that there will be options available to them in the future should they need a revision:

· If a patient who had received the DePuy ASR® XL Acetabular Head System for total hip replacement requires a revision surgery, the acetabular component could be revised with the Pinnacle Hip Solutions platform, which would be compatible with an existing well-fixed femoral stem.

· As with any hemi-resurfacing prosthesis, including the DePuy ASR® hemi arthroplasty, a patient requiring a revision procedure would generally be treated with a total hip replacement.

· For patients outside the U.S. treated with DePuy ASR® Hip Resurfacing (not commercially available in the U.S.), DePuy intends to maintain an inventory of ASR XL heads outside the U.S. for use on compatible DePuy femoral stems. This will allow surgeons outside the U.S. the option of retaining a well-fixed ASR Cup when appropriate as part of the revision procedure.

Lorie Gawreluk
Vice President, Worldwide Communications
DePuy, Inc.

Smith & Nephew's strong profits beat expectations
February 2010

Smith & Nephew (S&N), the hips-and-knees maker, posted higher profits in the final quarter of last year after the replacement joints market stabilized.

The market suffered during the recession, but started to recover in the second half.

Traditional hip and knee ranges, like its Legion knee, did well, particularly in the US, while products designed for younger, more active patients, such as the bone-sparing Birmingham Hip Resurfacing System, were weak.

Younger patients were more likely to put off surgery than retirees because they did not want to take time off work or balked at the cost.

"Our largest business, orthopaedics, saw a good finish to a tough year," said chief executive David Illingworth. "Market conditions were a little less difficult than in the first half."

He said it’s too early to say when patients who deferred operations might have them done, and S&N is struggling to push through price increases as governments and private clients have tightened their budgets. But Illingworth was hopeful that the $12bn  global market for replacement joints would improve, with consumer confidence returning and unemployment now falling.

S&N expects revenues in orthopaedics to grow at the market rate this year after lagging in 2009.

Profits before tax rose to $175m in the fourth quarter from $162m a year earlier, with revenues 11 per cent higher at $1.07bn, helped by strong sales at the wound management division.

Analysts and investors welcomed the results, and the shares closed up 4.3 per cent at 660p.

Thomas P. Gross, M.D. Midlands Orthpaedics p.a. Current status of uncemented femoral components in hip resurfacing Midlands Orthpaedics p.a.

 January, 2010

Uncemented femoral components for metal on metal total hip resurfacing have shown excellent results during the initial 3 years that I have been using this new technology. The early results that I have achieved in 0ver 800 cases since March 2007 are equivalent to the early results that I achieved with the same brand cemented femoral component.

Uncemented fixation of implants to bone is a proven technology that has generally surpassed the durability of cemented fixation to bone in traditional hip replacement surgery. In the long term (at 10 years) a higher percentage of hip implants using uncemented fixation still remain attached to the bone than cemented implants, especially in younger more active patients.

Fixation of total hip implants to bone can be accomplished by cement or by porous ingrowth technology (uncemented). Cement fixation is immediate. Cement is an acrylic material (methylmethacrylate) that is very brittle and also fairly toxic to bone cells. Cemented implants gradually loosen from the bone over time by reaction to the cement itself and due to gradual fatigue failure of this material. This process is faster in more active patients and faster in implant situations where the cement is stressed by shear forces rather than by compression forces.
 
Uncemented components are initially held to the bone by a very tight press-fit which is achieved by accurately preparing the bone so that the implant can be tightly hammered-on. The implants are so tightly wedged–on that the patient can bear full weight on them immediately. They do require a period of six to twelve months of bone ingrowth before they are considered well fixed. There is usually a small chance of failure of this bone ingrowth process in uncemented implants (<1%). But if ingrowth occurs, it is much more durable than cemented fixation and rarely fails in the long term.
 
Because orthopedic surgeons in America have come to a consensus on the superiority of uncemented fixation in total hips, uncemented fixation has virtually completely replaced cemented fixation in stemmed total hip replacements, despite the fact that these implants are more expensive. 99% of acetabular (socket) components that are used today are of the uncemented type, as are about 90% of femoral stems.
 
In hip resurfacing there is universal agreement that uncemented fixation is superior for the acetabular component. However, until recently, uncemented femoral components have not been available, therefore most hip resurfacing operations in the past have employed cemented fixation of the femoral component.
 
At the time that I began hip resurfacing in 1999, there was not yet general agreement that uncemented fixation was superior to cement in hip replacements. However, the evidence was mounting that uncemented fixation was better. I therefore did not think it was logical to use cemented fixation in hip resurfacing, an operation developed specifically with the more active younger patient in mind. The only companies pursuing hip resurfacing at the time were two small English companies: Corin and Midland Medical Technology (maker of the Birmingham implant). I suspect that they did not have the financial resources to develop a more complicated uncemented femoral component with the precision instrumentation required at that time. I originally proposed an uncemented femoral component to Corin 10 years ago, but they were unable to manufacture it at that time.
 
I therefore worked with Biomet on an uncemented femoral component and the precision instrumentation required for this implant for five years. I first began implanting it in March 2007. The Biomet component has a full coating of Titanium plasma spray under the entire under-surface of the femoral component. Recently we have added an additional layer of hydroxylappatite (HA) to increase the speed and extent of bone ingrowth. This is the best implant available to maximize the chance of bone ingrowth. When I started working with Biomet to develop an uncemented femoral component, Corin also started to work on one. They were able to bring it to market in Europe first; however, their component is only partially porous-coated (less than 50%) with Titanium (but it does have complete hydroxyl appetite coating). I personally do not believe this is good enough for long-term fixation (>10 years), but nobody knows for sure yet. It is not yet available in the US.
 
Theoretically, cement is the weak link when long-term (> 10 years) fixation of the femoral component is contemplated. If uncemented femoral components can be shown to achieve reliably high rates of ingrowth in the short term, they will probably outperform cemented femoral components in the long-term.
 
At this point with nearly 2-year follow-up data on a matched group of patients, I see no difference in results whether cement or uncemented fixation is used. At this point we can be fairly certain that bone ingrowth has occurred in these components. Except for two cases where osteonecrosis occurred in the femoral head at 1 year, we have had no failures of bone ingrowth in 430 patients that have are at least one year postop, and 191 that are at least two years postop.

In summary:

• Uncemented femoral resurfacing components are now available from BIOMET for any patient who desires them.
• No other companies are yet selling these in the US
• Corin has had an uncemented femoral component available in Europe for several years.
• At 2 years of follow-up there is no difference in the failure rate between cemented or uncemented femoral component.
• Uncemented fixation of implants is more durable at 10 years than cement in hip replacement surgery especially in young active patients.
• Most clinical data on hip surface replacement to date is based on an uncemented acetabular component and a cemented femoral component. 
• I now use uncemented components on virtually all hip resurfacing operations, unless the patient specifically requests the cemented femoral device. 

Thomas P. Gross, MD