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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 4th 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 devices 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 is 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 edge
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 edge loading and edge wear which results in a high
metal volume of debris early on. |
