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Wednesday, February 24. 2010
WHAT ABOUT NAVIGATION
Today navigation is still a tool that is not easy to use and
that needs a certain learning curve as resurfacing itself
also has.
So it is not a useful tool today for resurfacing beginners,
where it should be! It would be nice if it would be a help
at the start of the learning curve.
So can somebody with experience use it or should they use
it?
It is like doing a certain approach and having experience
with it, so it feels better and confident.
Most of the experienced surgeons do feel they do not need
it. MAYBE it could help.
BUT there are some things that have to be cleared out still
today:
*there is no correlation in most of the systems between
head and cup.
*Most of the systems only look to the head, and nobody
can tell us today what is now the best place to put the
implant
*It would be the best to use it for the cup because
there we have the most failures!
BUT AGAIN the most problems will be with females, that
easily have twisted pelvis on the table and smaller sizes,
and it is not sure it will have a big influence here.
If it is a system with preop CT of the pelvis to do the
acetabulum, the pictures are taken in SUPINE (lying down
position!). The patients walk and run on their hips, they do
not lie on them, and that can make a complete difference!
So we are not there yet, if something could help me to do
better surgery it would be navigation, but as it is today,
it is not a 100% proven project. I have today so designed
instruments that I call it navigation without navigation; of
course in other sites navigation really could help!
I do not know if the 7 malpositioned cups in my series of
3000 would have benefited with navigation, possibly yes, but
maybe would have had others where then the placement was
worse?
It is the future?, maybe, but not there yet at present for
everybody. That is why not everybody is using it, not just
because we would be to lazy, to old, to stubborn or
whatever.
If it would be used tomorrow in all cases from the start,
the worry is also there, that if the navigation fails we do
not know anymore what to do. All these facts should not be
used for marketing or publicity issues but left to the
orthopaedic community to make it better, try it and try to
succeed better, what prof.Cobb, myself and all others I
think try to do.
KOEN
koen de smet
hipsurgeon amc gent krijgslaan 181 9000 GENT BELGIUM
+3292525903
www.heup.be
anca clinic roma valle giulia ROMA ITALY
www.ancaclinic.it
Tuesday, February 23. 2010
There is some data indicating that navigation can improve
the accuracy of femoral component placement in hip
resurfacing. The real issue is "compared to what?" For an
inexperienced surgeon, navigation may help him avoid
component positioning problems that have been associated
with "the learning curve". However, for an experienced
surgeon, who has an established mechanical alignment system
with a high success rate - it is difficult to demonstrate an
advantage to him with a navigation system. Further, the
registration process takes a little time – so the
cost-to-benefit ratio for the experienced surgeon in a busy O.R. is questionable. The navigation systems are not hard
to learn to use, even for old guys like me!
A bigger challenge is acetabular component positioning.
This is true for total hips, and even more important for
resurfacing. There are 2 parts to the acetabular
positioning problem. The first is identifying the desired
position for that patient and the second is putting the cup
in that position. Keeping the pelvis in one position and
finding accurate pelvic/acetabular landmarks can be
challenging. The lateral opening angle is the easier part.
Most surgeons today agree that between 40 and 50 degrees is
desirable. Version is more complicated because the desired
acetabular version is dependent on femoral version.
Acceptable version is also related to the lateral opening
angle and the resultant bearing contact area. Again, the
issue is experience.
If I have any doubt about component positioning, I get an
intra-operative x-ray. Admittedly, there can be some
challenges to getting a good intra-operative view. For
what it’s worth, we did an x-ray review of my first 500
resurfacings (minimum 1 year follow-up). I have never had a
femoral neck fracture and all sockets are below 50 degrees
lateral opening.
Best wishes.
Thomas P. Schmalzried, M.D.
Tuesday, February 23. 2010
Computerized navigation has been around for a long time, in
total hips, total knees, and now hip resurfacing. A lot of
surgeons, including me, have tried it out and not seen an
advantage in all but very exceptional cases. Yet other
surgeons use it on every case.
This is what I think about computerized navigation: It is a
tool which can narrow the "bell-curve" of component
position, but the curve still has some spread. That helps a
surgeon avoid "outliers", or badly misplaced components.
Navigation does not make component position the exact same
every time, but it helps avoid those outliers. (If it was
the exact same every time there would be no bell-curve at
all.)
So, if a surgeon has no outliers, in other words if he is
doing a good job of keeping his personal bell-curve narrow,
there is no advantage to using computer navigation.
Alternatively, if a surgeon thinks he might accidentally
misalign a component so much that it would be considered an
outlier, the computer may prevent that.
Like any computer, what comes out depends on what went in.
Registering the anatomy (which tells the computer where
everything is) at the beginning of a computer-navigated
operation is not at all an exact science, but depends upon
knowledge and experience. It's the same with mechanical
alignment jigs. With either method, one should hope that the
surgeon is ready to adjust the verdict of the computer or
the jig to place the component accurately in the bones which
are clearly visible.
Are there any downsides to using a computer? Well, there is
the extra time involved, which prolongs the surgery (think
infections, blood clots). There is extra expense. There is
often one more person in the OR, and more traffic in the OR
can lead to infection. There is the possibility of surgical
complacency if the doctor believes in the infallibility of
computers.
I have heard this discussed at resurfacing meetings, and
people whom I respect more than any others in this field
have tried navigation and declared it "useless", and a
"waste of time". While unwilling to go quite that far, it
does make me think I am fine in continuing with mechanical
jigs.
Your question about doctors not having 100% "retention" due
to component malposition requires a reply. Personally, I
have not had any failures in almost 600 resurfacings due to
component malposition. I have 1 femoral neck fracture due to
leg presses 8 weeks after surgery, and one pelvis fracture
resulting from trauma 2 years after resurfacing. That's it.
But malposition is an important cause of fracture,
wear-related failure, and possibly pseudotumors as well, so
should be avoided.
Any surgeon "young" enough to learn hip resurfacing is
certainly young enough to learn the much easier task of
computer navigation, so people who consider someone too
"old" to learn navigation are being silly.
Similarly, a patient who would choose his surgeon based upon
their use of computer navigation is badly misguided. There
are many much more important issues to consider.
Having said all this, I wouldn't be surprised if at some
point in the future surgical navigation becomes more
accurate, easier, cheaper, and quicker. Robots will
substitute for doctors. Surgeons will look back on the old
days and shake their heads in amazement that we used to do
all this by hand.
Peter Brooks MD, FRCS(C)
Cleveland Clinic
Tuesday, February 23. 2010
Using computer navigation in joint surgery is a double
edged weapon. While potentially it can reduce the number of
outliers, it can also cause tremendous deviations and
absurd placements which would never be done with
conventional jigs. I have seen many examples of this done
elsewhere and referred to me for revision surgery.
Generally the input to the computer is made by a technique
known as bone morphing where the surgeon uses pointer probes
to point out the various bony landmarks to the computer. If
the surgeon makes an error in this step then it obviously
carries on in all further steps leading to a faulty
placement. To argue that it removes human error is most
irrational.
We have the brainlab navigation ( market leader in
navigation) in our unit since 2007 and I did a series of
cases at that time ( about 80 cases) . I have to say that
the femoral cap placement was inferior to my placement with
traditional jigs. However I found it useful when one had
distorted anatomy as in previous prox. femoral osteotomy. I
still use it for such cases.
There are many reasons in my opinion by which the
conventional jig is far superior to the navigation in hip
resurfacing.
1. bone morphing with the pointer probes damages the neck
capsule which I protect passionately during hip resurfacing
surgery and which I am sure is one of the key elements for
my success rate.
2. I use navigation routinely during my Total knee
replacements as the aim of the TKR surgery is to allign the
components to the hip and ankle which are not visible in the
surgical wound. In contrast in hip surgery the goal is not
to align hip component to the spine , pelvis or knee/ ankle.
The aim is to align components to local landmarks in the
surgical wound, the location of which is given to the
computer by the surgeon. Then the computer gives back the
same information which the surgeon offered in the first
place. ( this is unlike the TKR where the computer picks up
the hip on merely moving the hip and not morphing).
Arguments that the computer increases accuracy in hip
surgery is frankly absurd and have to be dismissed as
marketing techniques.
3. The concept of incorporating the combined anterversion
is now the key in operating on FAI ( Femoro- acetabular
impingement) which is the pathology in over 95 % of male
patients having primary osteoarthritis. This is a dynamic
assessment and can be done only with a jig using a lat
cortex pin and cannot be done with navigation.
Having said all of the above one must make a distinction
between what Prof. Cobb uses and what others use.
Prof . Cobb is the only one to my knowledge who uses a CT
based navigation. The CT gives information which the surgeon
cannot access unlike imageless navigation with all other
surgeons which depends on surgeon's input based on bone
morphing that defeats the whole purpose of navigation.
In conclusion I would like to say that imageless navigation
has very limited role in hip arthroplasty ( eg previosely
operated cases) and is an excellent tool in Knee
arthroplasty.
CT based navigation for hips which is still not available
commercially ( which prof. Cobb uses) may have a significant
role in hip arthroplasty. This has to be balanced with the
radiation dose for routine CT to be applied universally(
approx 30 -50 conventional x-ray dose )
wishing you the very best
with best regards
vijay bose
chennai
Monday, January 4. 2010
Surgery hits hip pocket
Click Here to Read Complete Article
By Sue Dunlevy From: The Daily Telegraph January 04, 2010
ONE in every 12 hip and knee replacements need corrective operations and new
surgical techniques are more susceptible to problems, according to Australia's
largest health insurer. Medibank Private has reviewed its data on the 3990 hip
replacements and 4860 knee replacements it paid for in 2008 and found "on
average surgeons perform revisions on 8.3 per cent of their total procedures"...
...The National Joint Replacement Registry, which is studying the reliability of
hip and knee replacements, has found newer joint replacements that are
cementless or hybrid are more likely to need further surgery than the older
cemented replacements...
...And research found the more reliable cement joint replacements are used in
just 23 per cent of hip replacement operations...
...The latest report from the National Joint Replacement Registry found that
three types of hip replacements - the ASR, Durom and Recap hip replacements -
had more than twice the risk of revision of other resurfacing prostheses. Hip
replacements with smaller femoral head sizes are also more likely to be revised.
The Allegretto knee, one of the most common knee-replacements used in Australia,
has a 10 per cent revision rate at 2.5 years, which is considerably greater than
other similar prostheses.
Friday, September 18. 2009
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.
Thursday, September 17. 2009
Click Here to Read Complete Story
A hip replacement was supposed to cure Mary Shelton's pain. Instead, the
Bakersfield woman replaced one pain with another.
Shelton and seven other local folks are suing the manufacturer and distributor
of a hip replacement system.
Instead of being pain free, those suing felt strong pains in their groin areas
for months, the lawsuits say...
All the suits are targeting the Durom Hip Resurfacing System. It's manufactured
by Zimmer Inc. of Indiana...
The suits allege that the Durom system is defective because bone and tissues
don't grow into them properly. A cup in the system has to be replaced with parts
from another manufacturer, Faulkner said.
Zimmer stands behind their product. It's not defective, said Irvine attorney
Michelle M. Fujimoto.
In paperwork filed with the court, the company says any problems can be blamed
on the doctors who implanted the product, or on unusual conditions in the
patients themselves...
The Durom system was first sold in 2006.
...the company has reported that about 15,000 have been implanted across the
nation
Tuesday, June 30. 2009
Link
http://www.nytimes.com/2009/06/11/business/11device.html?_r=2&ref=business
Published: June 10, 2009
Two House Democrats introduced a bill Wednesday to create a national database of patients who received artificial hips and knees, a system already used in some other countries to track how patients fare, reduce unnecessary surgeries and weed out inferior products...
...Patient registries, in areas like orthopedics, are expected to play an important role in “comparative effectiveness” reviews that the Obama administration hopes will help identify which medical procedures and products work best.
..."I think it will improve patient safety and outcomes and get rid of poorly performing devices," said Representative Pascrell...
...Makers of artificial joints and a professional association of surgeons who use them say that they support the idea of such a registry. But they said they were working to create one outside of government and argue that it could be more effective than the legislative proposal..
Read More
http://www.nytimes.com/2009/06/11/business/11device.html?_r=2&ref=business
Friday, April 10. 2009
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.
Read More by Clicking Here
Friday, April 10. 2009
"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.
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