Dr. Su made this presentation at the 11th Annual Hippy Gathering in San Jose,
CA on March 9, 2013
The presentation and meeting was dedicated to Vicky Marlow, Hip Resurfacing
Patient Advocate, who started the group and organized the Gatherings.
Vicky passed away in February 18, 2013.
Dr. Su responds to the recent Lancet
article - 2012
I would like to take this opportunity to comment on the
Lancet article, "Failure rates of metal-on-metal hip
resurfacings: analysis of data from the National Joint
Registry for England and Wales", by Professor AW Blom,
published on October 2, 2012.
First of all, this is an observational scientific study with
valid research design and questions; however, the
conclusions point out the limitations of registry studies
(more on this to follow). Overall the conclusions of the
study do NOT find any new information that has not already
been known since 2010: that certain hip resurfacing implants
perform better than others; that females do worse than males
with hip resurfacing; and that larger size implants have a
lower revision rate. These key pieces of information have
been well-known and discussed by experienced hip resurfacing
surgeons with their patients for at least 2 years already.
Furthermore, there are scientific congresses and courses
that have help spread this information to surgeons,
including the course that I chaired in May 2010.
What is new in this paper is the comparison to cemented,
hybrid, and uncemented total hip replacements (THR) of
various head sizes; the conclusion is that hip resurfacing
has a higher revision rate than any of these methods of
total hip replacement for most patients, and is not suitable
for most patients. The data cited is that 5 year revision
rates for 55 year old men was 2.6% with a 54mm hip
resurfacing femoral head, and 1.9% with a 28mm cemented
As this study was performed in the UK, I would like to point
out that fully cemented THR is not often performed in the
United States. In fact, it represents less than 5% of all
THR done in this country, and is on the decline. So, these
findings may not be applicable outside of the UK.
In looking at the data presented, there are actually some
comparable rates of survival between hip resurfacing and the
type of THR most commonly performed in the US. Namely, hip
resurfacings with femoral head diameters of 50mm had a 5
year revision rate of 4.2%; 52mm was 3.77%, and 54mm was
3.37%. For hybrid THR with a 28mm head, the 5 year revision
rate was 4.1%, and an uncemented THR was 4.18%. When divided
by gender, the results for males are even better. Men aged
55 years with a resurfacing implant of 50mm had a 7 year
revision rate of 3.27%; a 54mm head diameter was 2.47%.
Limitations of registry studies
The problem with a registry is that it collects a little bit
of information about a lot of people. Therefore, the outcome
measure that Professor Blom uses, revision rate, is a crude
indicator of how the implant is performing. Revision rate
will only include those patients who undergo a second, or
revision operation. It does not include those patients who
have had dislocations of their hip, or thigh pain, as many
of these patients will not have revision surgery for these
problems. It is an established fact that the dislocation
rate after hip resurfacing is about 10x lower than for THR;
thus the registry is not able to capture all the THR
patients who have had a complication such as dislocation or
thigh pain from the stem of the implant. Therefore the
reported superiority of THR has only to do with revision,
and does not include complications.
Besides a complication such as dislocation, the registry
does not have clinical information about how the patients
are functioning. Are the hip resurfacing patients
participating in more activities? Are they more satisfied
with their hips? Is their range of motion superior? Who has
a more normal gait? The registry is not able to answer these
questions – if a hip operation gave superior function, some
patients would consider it a worthwhile operation despite
the slightly higher risk of revision. There have been
several studies that demonstrate that hip resurfacing
patients are more active and have a higher satisfaction rate
than their THR counterparts.
Finally, a registry study is not able to account for surgeon
practices with regard to revision surgery. There is a
particular type of knee replacement, called a hinged knee,
that has a 100% survivorship in a national joint registry.
However, this is because there is no revision possible for
this type of implant – it simply cannot be revised because
it is an implant done for “last-resort” situations.
Therefore, in looking at the registry results, one could
conclude that this is the best implant available, a
conclusion that is clearly erroneous. What this registry is
unable to adjust for is the likelihood of revision based on
the type of implant. I can tell you from experience that
revising a hip resurfacing is the easiest revision to
perform; next is an uncemented or hybrid THR; and hardest to
revise is a cemented THR (because the parts are not easily
exchanged). Therefore, the registry results may be
reflective of the tendency for surgeons to indicate the
easiest type of revision operation.
I believe that there is valuable information from this
study, one that highlights the importance of patient
selection for hip resurfacing. However, I don’t feel that it
provides the entire picture of comparing patient activity,
function, and complications between the two procedures. I
also look to other international studies, particularly the
Australian National Joint Registry. Their 2012 report
demonstrates a revision rate of 4.2% at 7 years, for men
younger than 55 years who had hip resurfacing; their THR
counterparts had a 7 year revision rate of 4.6%. Thus, in
this patient population, hip resurfacing has a lower 7 year
revision rate as compared to total hip replacement.
The study by Blom et al. fails to account for the countless
lives that have been returned to one of function and
activity by hip resurfacing, which is why I don’t agree with
the recommendation of denying my patients this alternative
to total hip replacement.
Dr. Su's experience with hip resurfacing shows 1.3%
November 16, 2011
The retrospective study, which analyzed 925 hip resurfacings
performed by Edwin Su, MD, between 2004 and 2009 with a
minimum follow-up of 2 years, looked at three implants:
Wright Medical’s Conserve Plus Total Resurfacing Hip System,
Biomet Orthopedics’ ReCap Femoral Resurfacing System and
Smith & Nephew’s Birmingham Hip Resurfacing System. Conserve
Plus and the Biomet ReCap were used as part of clinical
trials, while the Birmingham hip was used after FDA approval
of the implant in 2006. Clinical scores and radiographs were
obtained at 1 month, 3 months, 1 year, and every subsequent
year. The hips in the study had a minimum of 2 year follow
up, both radiographically and clinically.
"[The Conserve Plus hip] was not FDA approved by our
government between 2004-2008, so we had to petition for each
patient to have the device, limiting the numbers of patients
receiving that implant," Su, from the Hospital for Special
Surgery in New York, said during his presentation at the
12th EFORT Congress 2011.
Su received training from some of the pioneers of hip
resurfacing, in both California and Europe, to gain the
experience necessary to perform the procedures. He used a
posterior approach during the procedures and was careful to
preserve the retinacular vessels and soft tissues to prevent
the need for reoperation. The implant specific guides were
used to ensure central positioning within the neck to
prevent notching, and cemented femoral fixation was used,
the study stated.
The study showed 12 revisions (1.3%) at a minimum follow-up
of 24 months. The K-M survival curve overall for the
procedure, using all 3 different implants, was 98.6% at 68
months. Su noted that these results compared favorably to
other published papers that describe short-term failure
rates of 8% and 13% for the procedure. The Conserve Plus
series had six revisions out of 157 cases (3.8%), which
involved two cup loosenings, three femoral loosenings and an
adverse metal reaction. The Birmingham series had six
revisions out of 748 cases (0.8%), and the ReCap had no
Limitations for the study include the limited amount of data
collected for certain implants, such as the ReCap, which had
20 implants compared to the Conserve Plus (157 implants) and
the Birmingham series (748 implants). The Conserve Plus
series also had a longer follow-up compared with the
"For a surgeon contemplating adopting resurfacing, one must
be concerned about the learning curve," Su said. "The
exposure is more difficult, it is more time-consuming, and
it is more sensitive to technical errors." However, with
careful patient selection, proper surgical training, and a
good implant, the success rate can be excellent.
•Su E. A single US surgeon experience with the adoption of
hip resurfacing using 3 different implants. Paper #1140.
Presented at the 12th EFORT Congress 2011. June 1-4.
•Berend KR, Lombardi AV, Adams JB and Sneller MA.
Unsatisfactory surgical learning curve with hip resurfacing.
J Bone Joint Surg Am. 2011; 93S:89-92.
•Mont MA, Seyler TM, Ulrich SD, et al. Effect of changing
indications and techniques on total hip resurfacing. Clin
•Edwin Su, MD, can be reached at the Hospital for Special
Surgery, 535 East 70th Street, New York, NY, 10021;
202-606-1128; email: email@example.com.
•Disclosure: Su provides consulting services for Smith and
Nephew Inc. on hip resurfacing products. Smith and Nephew
Inc. and Biomet Inc. have provided research support for
studies involving hip resurfacing.
Read Dr. Su's response to the NY Times article "Concerns
over 'Metal on Metal' Hip Implants" (March 4, 2010)
Dr. Su's response:
I have read and re-read this article with dismay. The writer
has chosen to focus upon rare occurrences of problems with
metal on metal joints. Most of these problems are avoidable
with good implant design and precise surgical technique.
Nonetheless, I do think it is important for yearly checkups
with me, x-rays of your hip, and blood metal level
monitoring. I've written a letter in response below, but I
fear they will not publish it, due to their preconceived
Letter to the Editor
I would like to comment on the article entitled
"Concerns over 'Metal on Metal' Hip Implants", dated March
4, 2010. As a hip surgeon who uses both metal on metal hip
resurfacing and total hip replacement implants, I feel it is
necessary to provide perspective on the issues raised in
First of all, metal on metal hip replacements have a rich
clinical history dating back to the 1970's. Cobalt and
chromium have been in use in hip surgery for over 30 years
because of their durability. In the last 5 years, the use of
metal on metal hip replacements has increased because of the
ability to create an artificial hip with a larger ball,
allowing for a greater stability to the joint and a high
activity level for patients.
While it is true that a metal on metal joint is less
forgiving, the key point is that the implants must be
properly positioned to ensure good function. Surgeons who
are experienced with the use of metal on metal hip implants
will have a low incidence of the problems described in the
article. At Hospital for Special Surgery, we have performed
over 2000 metal on metal hip resurfacings and replacements,
with less than a 1% incidence of problems requiring revision
Secondly, all artificial joint materials are subject to the
creation of debris; all debris material can be bioreactive,
leading to tissue and bone damage. This is not unique to
metal on metal hip implants, but can occur more rapidly if
the implants are not positioned well. I have revised many
more metal on polyethylene hips with tissue and bone damage,
than metal on metal implants!
Finally, there are patients for whom a metal on metal hip
implant may be a better choice than other materials. At
present, all hip resurfacing devices consist of these
metals. For these patients for whom bone preservation is
paramount, the metal surfaces are the only option.
I believe that focusing upon the rare, negative aspects of
metal on metal hip implants without highlighting the
benefits, is a case of "throwing the baby out with the
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