Does Hip Resurfacing Still Have a Role?

Bas A. Masri, M.D., FRCSC
Professor and Head
Department of Orthopaedics
University of British Columbia and Vancouver Acute HSDA
Vancouver, BC

Wow! Cyclic orthopaedics, here we go again. It seems that as a profession we never learn our lessons from previous generations. In the early 1980's, resurfacing was touted as a breakthrough to solve the problems with hip replacement surgery. There was a very short-lived euphoria, followed by a longer-lived era of fixing the problems that came with resurfacing. Even when I started practice 17 years ago, resurfacings of old were still being revised. Alas, resurfacing was not a new procedure at that time either!

 

Resurfacing of the femoral head predated total hip arthroplasty. In fact, Sir John Charnley invented the low friction arthroplasty because resurfacing did not work! He has been credited with initiating the concept of resurfacing back in 1951, yet he abandoned it in favour of total hip arthroplasty because it was not effective. In 1981, Dr. Bill Head wrote "Surface replacement of the hip, although not a new procedure, nevertheless should be considered an experimental one. In 1976 there were approximately 450 cases reported in the world literature, while in 1979 it was estimated that 5000 had been done1." I guess things never change. An experimental procedure with a checkered past, whose popularity skyrockets in three years, only to have early reports of failure two years later. Does this sound familiar? It sure does to me. We have not learned because we repeated the same mistakes in the 2000's. In his resurfacing series, Head reported a failure rate of 14 of 42 hips (33%) at a mean follow-up of 2.4 years, and maximum follow-up of 40 months. Most of the failures were on the femoral side. Those were cemented femoral components, not unlike today's designs. Granted, surgical technique is now better, the implants are better designed and the instrumentation is more precise, so it is reasonable to expect more favourable outcomes on the femur. Yet the fact remains, these are cemented implants that can loosen, avascular necrosis can happen underneath them and the neck can narrow (advocates of resurfacing state that although we don't know what neck narrowing means, it cannot be that bad), and they can ultimately fail. Despite that, we do them in more active patients and we expect them to out-perform hip replacements.

The second reason for failure of the Wagner resurfacings was polyethylene wear and cup loosening. Howie et al2 reported a 70% survivorship at five years and 40% survivorship at eight years, and made the astute observation that we should not really adopt technology without minimum ten-year results with no loss to follow-up. Enthusiasm for resurfacing very quickly faded. However, Drs. McMinn and Amstutz continued to work on resurfacing, and through several iterations and several generations of poorly functioning resurfacings, came up with a concept that can potentially mitigate the problems with polyethylene wear that plagued previous generations of resurfacing. Cementless socket fixation will "theoretically" eliminate loosening. Metal-on-metal bearing surfaces will eliminate wear, and the hips will last forever and provide a more 'normal feeling' hip with better biomechanics, proprioceptive feedback, and better patient outcomes. This theory led, not only to an explosion in the numbers of hip resurfacings, but also in the variety of implants on the market. Reality, however, did not deliver on the promise of resurfacing. The prophecy of better outcome and perpetual function became a harbinger of disaster for patients, and loss of credibility for the profession. Each manufacturer had a resurfacing design and now only one type of implant, the Birmingham Hip Resurfacing has stood the test of time in the Australian Joint Registry, but only in young male patients.

So What Happened with Modern Resurfacing?
While many were concerned about the long-term risk of metal ions from metal wear, no one paid attention to the potential for short-term harm, until the Oxford group drew attention to an alarming early complication of resurfacing, and indeed of all metal-on-metal hip replacements. Inflammatory pseudotumours, more euphemistically termed "Adverse Local Tissue Reactions" or "Adverse Reactions to Metal Debris" were noted. Since then, there has been an explosion of literature about these pseudotomours, which are thought to be related to metal ions locally within the soft tissue, and cause variable amounts of soft tissue destruction. They are much more common in women, and are related to smaller femoral heads and when they occur, they are potentially disastrous. There is also literature suggesting that revision total hip arthroplasty for pseudotumours yield worse outcomes than revisions for other reasons. In our pseudotumour revision experience, we have seen a higher prevalence of failure of ingrowth, sciatic nerve palsy due to pseudotumour involvement of the nerve, femoral nerve palsy and external iliac vein occlusion and permanent swelling of the leg with pseudotumours. We, as well as others, have reported on a very high rate of pseudotumours in asymptomatic individuals with resurfacing and with large head metal-on-metal hip replacements.

Clearly, we still do not know much about pseudotumours and adverse reactions to metal debris. What will be the natural history of asymptomatic pseudotumours? What is the real magnitude of the problem? We simply don't know.

So has the promise of resurfacing been realized? Some studies have reported superior function after hip resurfacing, but they suffer from selection bias. Our randomized controlled trial showed no difference in patient-reported quality of life outcomes whatsoever. In reality, there is probably very little difference in function between resurfacing and total hip arthroplasty when one corrects for patient demographics. Not a single study has reported better biomechanics. In fact, it is more difficult to restore offset in resurfacing, but this is probably of no relevance. Resurfacing promised better proprioceptive feedback, whatever that is. Not a single study has actually proven this. Resurfacing does, however, offer a lower dislocation rate.

What about the long-term outcome of resurfacing? The Australian National Joint Replacement Registry showed equivalent results at ten years for males under the age of 65 and with femoral head diameters over 50 mm. Interestingly, revision of resurfacing was less predictable than primary total hip replacement with re-revision rates of 11% at five years. As such, early failures of resurfacing will have a negative impact on the overall outcome.

Again, has the promise of resurfacing been achieved? Yes, but only for males, under the age of 65 with large stature. As such, patient selection is extremely important, and I would submit that surgeon selection is even more important. This should not be an operation that is only done on occasion. The risks are high; the technique is demanding so as to avoid malalignment that leads to either high rates of metal ion generation or femoral neck fracture. The consequence of failure is worse than those of hip replacements. Thus, if resurfacing is to be done, it should be done by a select few surgeons and not by all.

In 2012, is there a role for resurfacing? In my practice, there is no role because I have yet to identify a patient population in whom the results of resurfacing are better than those of hip replacement. For young large stature males, the results are the same, but the cost is much higher. From a socioeconomic perspective, it makes no sense for all of us as tax-payers to pay for an operation that is significantly more expensive and no better than the tried and true gold standard.

As a youngish male in his late 40's, would I have a resurfacing in 2012? Not on your life!

References

  1. Head W.C., Wagner Surface Replacement Arthroplasty of the Hip: Analysis of 14 failures in 41 hips. J Bone Joint Surg [Am] 1981:63A:420-427
  2. Howie D.W., Campbell D., McGree M., Cornish B.L. Wagner Resurfacing Hip Arthroplasty - The results of 100 consecutive arthroplasties after 8-10 years. J Bone Joint Surg 1990; [Am] 72: 708-714

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