This week’s Orthopaedic Crossfire® debate was part of a landmark event, the first Brazilian CCJR Meeting. The event, which took place in September 2014, was held in Iguassu Falls. The topic is “Metal-Metal Surface Replacement: Still a Viable Option.” For the proposition is Edwin Su, M.D. of Hospital for Special Surgery (HSS). Against the proposition is Adolph Lombardi, M.D. of Joint Implant Surgeons, Inc. Moderating is Aaron Rosenberg, M.D. from Rush University Medical Center.
Dr. Su: “We know that total hip replacement [THR] is one of the most successful operations ever devised. Our own government has said that it’s highly cost effective, and it’s clearly the gold standard in the treatment of arthritis. So why change?”
“The Swedish hip registry and data worldwide shows that the survival rate of these implants dramatically decreases between 10 and 20 years such that about 40% of these implants need revision. Dislocation is still a problem with THR. It is on the rise as a reason for revision, likely because patients are more active and younger, and are doing things with their implants that perhaps the implant was not designed to accommodate.”
“There are many benefits to resurfacing: bone preservation, joint stability, better reproduction of the natural anatomy (in terms of length, offset, and anteversion), more physiologic bone loading, and it leads to a greater activity level. It has been argued by critics that we save femoral bone at the expense of acetabular bone, but we showed in a cadaveric study that we didn’t remove any additional acetabular bone in order to save the femoral head.”
“Regarding joint stability, there are patients who require a high range of motion [ROM]…and large diameter metal-metal hips are no longer being used. In terms of more physiologic loading of bone, the hip replacement takes the load from the top, loads it through the stem, and converts it into hoop stresses. This is a good way to load the bone, but it’s not natural. A hip resurfacing accepts the load from the top and loads it through the femoral neck…as intended. With a resurfacing it’s not going to break, but with a hip replacement you could potentially break that implant.”
“There are also cases of male patients with a varus neck and very high offset that if you try to template it for a THR there is no stem that will match that offset. A hip resurfacing would be able to match that length and offset because it’s just a covering over the patient’s anatomy.”
“There are now several studies looking at the activity level of resurfacing compared to THR. Professor Haddad from London has a study—now at 10 years—comparing THR patients to resurfacing patients. He found significantly higher function and activity scores for the latter group at one, five, and ten years. A study by Bob Barrack looked at a questionnaire administered to patients with hip replacements and hip resurfacings; fewer resurfacing patients reported limitations.”
“Hip resurfacings in certain subgroups are performing well in national joint registries. There is a higher rate of revision in females. In males under the age of 65 there is about a 6% revision rate for resurfacing at ten years; for the same group the revision rate for THR is 8%.”
“Metal-metal hip resurfacing is different than a metal hip replacement. A study done in 2010 by Don Garbuz et al. found that metal levels were much higher in metal-metal THR compared to resurfacing. We now know that there is wear and corrosion at the taper level in metal-metal THR. And the soft tissue reactions with metal-metal THR are very different than we see with metal-metal hip resurfacing.”
Dr. Lombardi: “Ed mentioned all of the pros. Here are the cons: a more difficult operation, a high learning curve, few patients meet the criteria, and there is concern over metal ion toxicity. Are the ‘pros’ really ‘pros?’”
“As for femoral bone preservation, on the acetabular side there is varying literature. A 2006 study from Longhead et al. in The Bone and Joint Journal (formerly The Journal of Bone and Joint Surgery (Br)) says that there is a statistically higher volume of bone reamed from the acetabulum. Another study from Crawford et al. shows 311% more bone removed with resurfacing. A 2009 paper from Brennan et al. on 62 patients said that in resurfacing, use of an appropriately small femoral component avoids oversizing the cup and removing excessive bone.”
“Regarding range of motion, a 2008 study by Kluess et al. involved 3D computer-aided design (CAD) models of the hip and eight different resurfacing systems. They found 31-48 degrees less ROM than with a 32mm THA [total hip arthroplasty]. A 2008 study by Bengs et al. looked at eight hip replacement designs (three resurfacing, five THA); they found statistically greater ROM with THA than with the resurfacing. In their 2009 study, Le Duff et al. found that there was not a difference between resurfacing and THA if the cup was adequately positioned.”
“Turning to gait analysis, Petersen et al. did a study in 2010 and found similar improvements in the mechanics of gait (except for peak abductor moments, which were actually more improved in the THA group). And in 2009 Lavigne et al. randomized 48 patients to either resurfacing or THA and found no difference in the gait analysis.”
“Registry data on hip resurfacing demonstrate an overall increased failure rate compared with THA, except in males younger than 65 who are diagnosed with primary osteoarthritis are likely the key group…and those with a head diameter larger than 50mm. Data from the Nordic registry shows a higher failure rate of hip resurfacings versus THA. The Australian registry shows an eight year cumulative percent revision rate of 5.3% (resurfacing) versus 4% (THA). The Finnish registry showed a higher resurfacing revision risk in females, in ASR [articular surface replacement] implants, and in low hospital procedure volume.”
“As for metal ions, the literature shows a bit higher metal ion release in the large head metal-metals. A 2009 resurfacing study by Della Valle et al. involved 537 cases where they had 40 adverse events, 14 component revisions, and a significant number of complications in patients who were older than 55 and female. A 2009 meta-analysis by Springer et al. involved 20 total hip papers and 15 resurfacing papers; follow-up was about eight years for THA and roughly four years for resurfacing. There were two times the number of revisions for mechanical failure in the resurfacing group as compared to the THA group.”
“In our own experience with 73 metal-metal hips we had an 8% revision rate with an average follow-up of 25 months. We felt that this was unacceptably high and thus we significantly reduced our utilization of hip resurfacing.”
Moderator Rosenberg: “Ed?”
Dr. Su: “One of the points you made was that a THR should have more movement than a hip resurfacing. I agree because the resurfacing has the large femoral neck that you’ve maintained, so the head-neck ratio is smaller. I never tell patients that they’re going to have greater ROM, but I do say that their dislocation rate is lower and that they will have a more stable joint. As for metal ions, that is a valid concern and it requires more discussion with the patient and more maintenance on the part of the surgeon. But the resurfacing data regarding activity is starting to separate out from the THAs at about 10 years.”
Moderator Rosenberg: “So as you go into the larger sizes there have been some reports that this increases the likelihood that the patient will have groin pain. Adolph?”
Dr. Lombardi: “I’ve actually seen more of the iliopsoas tendonitis as I’ve switched my approach from a direct lateral to a direct anterior. I think in our zealousness to put the cup in a more flat position we probably irritate the iliopsoas proximally. When you put in these large cups make sure you feel around and get the cup well seated and feel around anteriorly to ensure that you don’t have exposed metal there.”
Dr. Su: “I agree. With the resurfacing in particular, I think groin pain can be an issue at the outset because you have to twist the leg so much that it’s putting a lot of stress on the iliopsoas. But if you let it relax and you don’t stress that muscle during the recovery, it does go away.”
Moderator Rosenberg: “Ed, you said that you have a separate discussion with patients about metal ions. What do you tell them?”
Dr. Su: “I say that the release of metal ions is inevitable with the bearing of two metal pieces rubbing together. They circulate in the peripheral blood, but the kidneys do a great job of filtering it. Usually we’re seeing ranges in the three or four parts per billion or less. If it goes above that then I get cross sectional imaging to see if they’re having soft tissue reactions or fluid collections.”
Moderator Rosenberg: “Do you think it requires a separate consent form?”
Dr. Su: “We do have one.”
Dr. Lombardi: “We didn’t have a separate form when I was doing large head metal-metals, but we had the exact discussion that Ed has. But if you’re going to do one today I would suggest getting a separate consent form.”
Moderator Rosenberg: “Ed, you’re specific indications have narrowed over time. Is this implant ideal for males only?”
Dr. Su: “There is some data indicating that it is size related. In a skeletally large female it can be done, but I talk to them about the potential for an allergic response…and I try to dissuade them from this procedure. I typically just do it in males.”
Moderator Rosenberg: “What are the contraindications in a younger male?”
Dr. Su: “Osteonecrosis involving more than 30% of the femoral head, small bone size (less than 46mm), dysplasia.”
Moderator Rosenberg: “Thank you, gentlemen.”
Please visit www.CCJR.com to register for the 2014 CCJR Winter Meeting, December 10 – 13 in Orlando.
