“Surface replacement provides several advantages over THR, including bone preservation, greater stability, and a higher activity level, ” says Edwin Su. Michael Dunbar disagrees, saying, “Resurfacing is more invasive, has worse outcomes, produces metal ions and pseudotumors, is hard to revise, and does not provide better function.”
This week’s Orthopaedic Crossfire® debate is “Surface Replacement Arthroplasty: A Viable Option.” For the proposition is Edwin P. Su, M.D. from Hospital for Special Surgery (HSS); against the proposition is Michael J. Dunbar, M.D., F.R.C.S.(C), Ph.D. from Dalhousie University in Halifax, Nova Scotia. Moderating is Clive P. Duncan, M.D., F.R.C.S.(C) of the University of British Columbia.
Dr. Su: “A total hip replacement (THR) is one of the most successful operations ever devised, so we must have clear evidence as to why we might want to change that. The problem with THR is wear and osteolysis. If you look at the Swedish Registry—stratified by patient age—you see in young patients that at 10 years there is a dramatic decrease in the survival of these implants…with almost a 40% revision rate by 20 years.”
“We also know that dislocation is an issue, and dislocation as a reason for revision is increasing. I think that is because patients are more active and younger. The challenge is doing a THR in young, active patients; their increased activity may lead to an earlier need for revision.”
“The benefits of hip resurfacing are bone preservation, joint stability, better reproduction of natural anatomy, and it loads the bone more physiologically. And it may lead to a higher activity level for our patients. It is indisputable that hip resurfacing preserves femoral bone. We did a cadaver study to look at both the acetabular and femoral sides. One of the arguments against resurfacing is that it takes more bone from the acetabulum. But we found that this isn’t true with modern implants. It also leads to a more stable joint.”
“We know that in our patients dislocation can be an issue. Some surgeons were going toward large diameter metal-on-metal THR to solve that problem, but it’s no longer being used in the U.S. So how to achieve stability in a patient that needs it? It is a more physiologic loading of bone. In a total hip it receives load from the top, it’s transmitted through the stem, and is converted into hoop stresses. But a hip resurfacing would load the bone from the top into the femoral neck as it should be. And what will happen if you continually load a THR you can get breakage. With a hip resurfacing that’s not possible.”
“I think it also leads to a better restoration of normal hip mechanics. And some interesting data was presented at the International Society for Technology in Arthroplasty in 2012 by Haddad showing that the activity level in a group of patients randomized to either THR or hip resurfacing was higher in the latter group. Hip resurfacing in certain subgroups are performing well in national joint registries. If you examine the revision rate of hip resurfacing you see that females have a higher revision rate, almost double, than males. Let’s look at the data by age stratification. For hip resurfacings in men under the age of 65, the 10 year results were a 6% revision rate for resurfacing; for THR—same age group—at 10 years it was 8% for males and females. The hip resurfacing group has a lower revision rate in this age population in males in Australia.”
“This data can help us select patients who will have the greatest success with resurfacing, namely, men under 65 with primary osteoarthritis and a large femoral head size.”
Dr. Dunbar: “In the UK from 2004 to’06 almost half of all patients under the age of 55 received a resurfacing, and it was almost a third in Australia. This was not the case in the Scandinavian countries. And I would implore this great nation to avoid this mistake.”
“The primary thrust is that resurfacing is meant for the young male. We should drill down and look at the same slides in an opposite manner to see where this evidence comes from. The major advantage is survivorship. Is that true? In the Australian registry we find data on 12, 000 patients; yes, it’s the older patients that have a higher risk factor. But all-comers included, resurfacing has a worse outcome than primary THR. If you break that out, females come out a disadvantage, so perhaps at best young males are equivalent to a well done total hip. But there’s no advantage in the literature for resurfacing over THR.”
“The data from England and Wales is more profound, and discriminates itself better in terms of the fact that resurfacing is significantly worse than all other constructs in the UK. Even in the U.S. with early reports of the Durom there are high failure rates for resurfacing at five years. So this has not been a panacea to increase our survivorship.”
“One of the reasons that survivorship is reduced is because of the generation of metal ions. It’s a fact that if you use a metal-metal resurfacing you are more likely to produce metal ions. In a paper we did looking at an early series of resurfacing, we saw significantly elevated metal ions. What was more concerning was that those ions remained elevated after two years. We’ve been told in the past that with the bedding in these ions will abate, but this was not our experience. And we know that these ions can cause pseudotumors. A well done report on 129 patients from the Netherlands showed that 28% of patients at five years had some evidence of pseudotumor with MRI imaging.”
“When you do use resurfacing, because of these metal ions, you get into difficult conversations with your patients, and difficult management treatment algorithms. If there is pain, you need to follow metal ions; you must collect serum and urine and that can be difficult to collect and interpret. If they’re elevated and the patient is symptomatic you likely need cross sectional imaging, which is difficult to obtain because of the metal artifact. And you may need to revise the patient because of these high metal ions. Why would you want these headaches for something that’s not going to give you a big advantage?”
“Another reason why we promote resurfacing is that it is less invasive than THA. I believe this is false. In my experience this was THE most invasive procedure we had to do because you could not remove the femoral neck and head to get access to the acetabulum. It’s a massive dissection because these are often young, fit males with large muscles. Some suggest that this has led to neck fracture. Also associated with this is the very unusual phenomenon of neck narrowing.”
“With respect to preservation of the bone stock there’s no question that you don’t violate the femoral canal. But what’s the evidence about the outcome of preserving this bone stock? Looking at the Australian Registry we see 397 cases of resurfacing that went on to failure and then were revised, what were the outcomes of those procedures? The revised cases—despite the preserved bone stock in the femur—did significantly worse than a primary THA.”
“Some say large head can improve function, but where is the evidence? In a Charnley award winning paper (Lavigne, et al.) of head to head, randomized comparison of large head metal-metal total hip to resurfacing, there was no advantage to the resurfacing over the THR in terms of restoring biomechanics, gait, etc.”
“If you think about it, yes, there is a larger femoral head with a resurfacing that may give you an advantage, it’s not the femoral head by itself that’s the issue…it’s the ratio of the head to the neck. In some cases you have an advantage using a total hip with respect to ROM because the clearance is greater.”
Moderator Duncan: “Ed?”
Dr. Su: “There are concerns with resurfacing with regard to the metal-metal bearing. It requires increased monitoring, timely discussions with your patients, and an understanding on their part that they will have elevation in their metal ion levels for their entire lives. But some of the data you presented from the registries…those were the population at large and they didn’t stratify into the best patient scenarios. So that’s where we can benefit from the registries, i.e., tailor our indications for the patients who are going to do the best.”
Dr. Dunbar: “We do have to be very careful in interpreting the registry data because it can homogenize the data. But it does look at an entire nation’s experience. To your point that it reduces the dislocation rate, I think that perhaps dislocation rate shouldn’t be an issue in that if you do a high enough volume with the right approach and appropriate surgical technique, then dislocation is not a big issue. Instead, we’ve chased our tail trying to reduce dislocation rate by changing the implants. We’re finding out that if we have a group of low volume surgeons using an implant that’s supposed to be forgiving it actually turns out to be unforgiving because mal-positioning on a metal-metal resurfacing is what causes the runaway metal ions. The difference is that you’re an expert on this technique; I don’t do as many. We need to discuss the entire surgical audience who might take these on.”
Moderator Duncan: “Mike, under what circumstances will you agree to do a surface replacement?”
Dr. Dunbar: “Someone who had had some sort of fixation previously within the femoral canal…or someone with a profound level of offset that you may feel you can’t reconstitute with a typical or even an advanced implant. In that case I’d send them to a high volume resurfacing surgeon.”
Moderator Duncan: “Ed, what is in the future in terms of technological and training advances that may allow us to revisit this with more enthusiasm (because it has waned in North America)?”
Dr. Su: “The challenge is to remove the metal from the equation, as well as remove the production of cobalt and chromium. In the past we’ve used metal-poly, however we didn’t have highly crosslinked poly so they were subject to massive osteolysis. There are other material possibilities.”
Moderator Duncan: “Tell us about your follow-up surveillance of these patients.”
Dr. Su: “Those with a metal-metal resurfacing return annually; those with metal-poly hips return every five years. So those in the former category get annual X-rays and I monitor their metal levels at 1, 3, 5, 7, 10 years. If it’s above a certain level then I will get cross sectional imaging to look at the soft tissues.”
Moderator Duncan: “So the femoral side fails. Are you going to leave the acetabular component alone and go with a metal-metal revision or revise both sides of the joint?”
Dr. Su: “In the past I’ve removed both components and revised the acetabulum. There is a dual mobility option…an off label option where we can use that large poly head to articulate with and save the socket.”
Moderator Duncan: “Thank you both.”
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I’m a 57 year old male patient, extremely active & considering my options. I’m also a type 1 diabetic, since age 12, but have NO complications & have received the resurface blessing from my endocrinologist. Very informative debate. Fascinating though, how it appears there isn’t clear consensus yet, on the physical superiority alone, of either procedure.
I am a 76yo male who had HR by Dr. Su in the fall of 2008. For 10 years I have been pain free with no restrictions. My cobalt & chromium levels are w/I limits. Only know my experience, but highly recommend HR by Edwin Su. The surgeon makes the difference.