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Hip resurfacing: Why I do not offer it
Higher complication and failure rates and no appreciable advantages are among the reasons.
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I have done many hip resurfacings in the past, but I currently have stopped doing the procedure. I have the dubious distinction of being the first in Canada to do it.
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In Canada we are not allowed to advertise directly to our patients, but they are subject to the Internet and, of course, they come in asking for the procedure. I am now going to tell you, what I tell my patients when I am telling them why I do not offer them resurfacing.
They say they want it because: it is less invasive; it is bone conserving; it is going to give better function and range of motion; and because it lasts longer.
Invasive or conserving?
Is it less invasive? Well, I think that is nonsense. It is not less invasive. These are often young, big males with big muscles, who want this procedure. My most common observation is as I was doing this procedure was ‘Damn, this would have been such an easy total hip. Why am I struggling to do this?’
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Trying to do the resurfacing arthroplasty is analogous to doing an acetabular revision with a monoblock femoral component in place.
Is it bone conserving? If you take slightly more from the bone stock on the acetabular side, and you take a bit less bone on the femoral side, it is a wash and has no significance. Where is the proof that resurfacing would improve your function and the long-term survivorship after the revision?
There is an unusual phenomenon of bone loss, ie, neck narrowing, that occurs in a percentage of patients and we really do not understand fully why it happens. Another is, and I have seen this in a number of patients, bone resorption that starts at the superior lateral corner of the acetabular component. I think this is a function of the hard-on-hard bearing surface with too much force being seen in the area. Therefore, in some cases we are starting to lose bone.
Function and range of motion
What about better function and range of motion? I think it is not as simple as saying you have a big head, therefore, you get a better range of motion because it is about the head-to-neck ratio. I would submit that you can get a better ratio with a total hip arthroplasty (THA) that is done well, and, in fact, get a better range of motion with less impingement.
To illustrate the clinical significance of the ratio, an independent multi-centered Canadian study I was involved with, led by Dr. Paul Kim, looked at 200 consecutive patients with procedures performed through three different surgical approaches. We found that, in respect to range of motion and clearance and the head-to-neck ratio, that 9 (4.5%) of our patients had significant complications with respect to groin pain likely related to impingement. So, the head-to-neck ratio is significant and important. Also, with respect to functional outcomes another independent series from Andrew J. Shimmin, MD, from Australia, looked at 230 patients and found five major nerve palsies in their series (2.2%) with the Birmingham Hip. It is just not acceptable in my opinion to take our best operation, in terms of cost effectiveness and improvement in quality of life, change it and get major complications.
Does resurfacing last longer? In our series, and this may be due to the learning curve but it is significant, nine hips were revised within the first 2 years for a 4.5% failure rate. That would be unacceptable in THA. The issue to me is where is the evidence in terms of the properly done randomized control trials? Have we looked at THA compared to resurfacing arthroplasty to figure out do they have better function and better long-term outcomes? The data are just not present. I admit it is difficult to do these studies because the patients who come looking for it are biased, they are usually young, bigger, and they are not interested in being randomized in a trial to figure this out. So, we are in a bit of a quandary, and we are lacking the data to have an objective discussion about this.
Metal ions
We have heard about the metal ion issues. I tell my patients, that there is no evidence that carcinogenesis occurs. However, a meta-analysis of over 300,000 hips, showed hypersensitivity in a few cases. Maybe we are looking too hard, but there is some smoking-gun evidence that there are some hypersensitivity issues going on with the metal ions. I think we all agree that we should try to limit this technology from women of potential childbearing age and we are also concerned with renal failure patients. So, if we are concerned about these groups then we must submit to ourselves that there is some underlying concern about these metal ions. In our study, when we looked at these patients; the metal ions did go up over time and cobalt, and chromium were seen in their serum and urine. Two interesting points: the levels do not go up and then go down, they stayed up throughout the course of the study; and we had a lot of outliers in this series a few of whom raised concerns about what does it mean to metal ions this high in your body? This is an unresolved issue in my opinion.
With respect to resurfacing arthroplasty, and this is honestly what I tell my patients, I think there is a higher complication rate, particularly in the early period; there is a higher failure rate, particularly in the early period; and there are no appreciable advantages right now that I can see. Therefore, why would I offer it to you?
For more information:
- Michael J. Dunbar, MD, FRCS(C), PhD, associate professor, Department of Surgery, Division of Orthopaedics, and clinical research scholar, Dalhousie University, can be reached at 902-473-7337; e-mail: michael.dunbar@dal.ca. He has no direct financial interest in any products or companies mentioned in this article.
Reference:
- Dunbar MJ. Hip resurfacing — Con. Presented at the Tenth Annual Insall Scott Kelly Institute Sports Medicine and Total Knee & Hip Symposium. Sept. 14-16. New York.