Dr. Su Interview by Patricia Walter Aug. 3, 2013 in Columbus, OHDr. Su Interview by Patricia Walter Aug. 3, 2013 from Surface Hippy Videos on Vimeo.
Dr. Edwin Su Hip Resurfacing Talk Part 1 – Part 6
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 metal-on-polyethylene THR.
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% complication rate
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 revisions.
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 Birmingham series.
“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. Copenhagen. •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 Orthop, 2007;465:63-70 •Edwin Su, MD, can be reached at the Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021; 202-606-1128; email: firstname.lastname@example.org. •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 biases.
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 this article.
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 surgery.
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 bathwater”.
Link to Frequently Asked HR Questions Answered by Dr. Su Link to General Hip Resurfacing Questions Answered by Dr. Su Link to Pre-Op Surgical Questions Answered by Dr. Su Link to Surgical Questions Answered by Dr. Su Link to Post-Op Questions Answered by Dr. Su