Robert Barrack says, “Our work has found significant differences favoring surface replacement.” But, in Keith Berend’s view: “This is not a viable option for most patients or surgeons.”
This week’s Orthopaedic Crossfire® debate is “Surface Replacement Arthroplasty: Still a Viable Option.” For the proposition is Robert L. Barrack, M.D. from Washington University School of Medicine in St. Louis, Missouri; against the proposition is Keith R. Berend, M.D. from Mt. Carmel New Albany Surgical Hospital in Ohio. Moderating is Thomas Thornhill, M.D. from Harvard Medical School.
Dr. Barrack: “Given the high rate of success of total hip arthroplasty (THA), high risk alternatives are not warranted. So surface replacement (SRA) must demonstrate a similar complication rate, there must be some clinical advantage, and there must be a reasonable learning curve to warrant continued use of this procedure.”
“There are major short term complications with THA that lead to morbidity, dissatisfaction, and lawsuits. Where can we improve? Dislocation and limb lengthening are big problems; dislocation rates are generally accepted as being lower in SRA, but the lower incidence of perceived limb length discrepancy is among the potential advantages.”
“Other potential advantages have been suggested and include a higher level of function/activity, less thigh pain, and less stress shielding. The problems with prior studies are that they’ve been low in numbers, been underpowered, and had a lot of potential for observer bias because of the absence of independent, blinded parties.”
“We need to document: clinical advantage, a reasonable learning curve in the hands of a number of surgeons, and less stress shielding. Also, the clinical results…not just at specialty centers, but in large data sets.”
“We did a national multicenter study to see if there was a discernible clinical difference among current THA implants with advanced bearings compared to surface replacements in young, active patients. We overcame observer bias by using an unbiased, blinded survey center that has expertise in administering questionnaires for federal and state agencies.”
“There were over 800 patients; we found significant differences that favor surface replacement. There is a substantial difference in those that perceived a limb length discrepancy; thigh pain is perceived much more frequently by total hip patients than by SRA patients. THA patients even said that they limped more frequently than SRA patients; also, the SRA patients were much more active.”
“Among the very high activity patients, surface replacements were much more likely to return to their most favored activity. We documented stress shielding in 90 patients, two-thirds with SRA, one-third who wanted SRA but either had a large cyst or limb length discrepancy; and we confirmed substantial stress shielding in the proximal femur for THA patients. At six months SRA has over 100% of the bone density preoperatively…and this is present even in the femoral neck at six months. Based on this, we now let our patients resume impact activities at six months. This study was recognized with the Marshall Urist Award.”
“We have done two studies on the learning curve. After FDA approval we looked at 600 cases from 90 surgeons; then we compiled data from five total joint specialists. Among all surgeons—who had done only an average of six cases—the total complication rate was 7%—which is almost the same complication rate as in a Medicare database for total hips. Among specialists, the complication rate was extremely low—2%—one-fourth that of the general population.
“Data from the Australian registry says that among young males with osteoarthritis (OA) the revision rate at five years is lower with resurfacing than conventional total hip. The facts speak for themselves. There’s no doubt that this is a viable option. It’s been identified by the American Academy of Orthopaedic Surgeons Technology Review as better or equivalent in some patient groups. And the same center that coined the term ‘pseudotumors’ in specific patient groups—Oxford—reported outstanding results in other patient groups.”
“Superb SRA results have been reported from Oxford by Dr. Berend’s mobile-bearing mentors. At their center, among males with OA, they had a 10-year survival rate of 99%. One disclaimer: it is dependent on the prosthesis. Most of this data is from one particular prosthesis; the results are highly variable depending on the device, patient selection, and surgeon. And much like mobile-bearing knees, it is a specialty procedure that isn’t for all patients and not for all surgeons.”
Dr. Berend: “This is not a viable option for most patients or surgeons. The first thing we always hear is that in the patient’s perception is that this is a bone conserving operation. Clearly, if we cut the top of the femoral neck off we’re discarding some bone, versus just capping off the top of the femoral head as we do with a resurfacing. Unfortunately there are multiple studies showing that there is more acetabular bone loss with resurfacing than with conventional total hip replacement. A study from Crawford found over 300% more bone loss on the acetabular side. This is something patients don’t understand. They are told things like a surgical amputation of the femoral head, but they don’t understand that in order to put in a big enough acetabular component and a big enough ball, it requires more bone loss, not less.”
“What about the data Robert mentioned on dislocation rate and better range of motion? It’s actually untrue. We all understand head/neck ratio, and clearly if we just put a cap on the end of the thigh bone, the head/neck ratio is significantly different than if we use even a 32mm head. In a computational study from Kluess the average range of motion with resurfacing was up to 50 degrees less than that of a 32mm total hip. And in the model no resurfacings allowed for flexion of 90 degrees without impingement—either bony or mechanical.”
“Lavigne’s study showed that impingement was significantly higher with resurfacing and range of motion was significantly greater with total hip. Robert discussed functional outcomes, and in his phone survey of patients who had already received resurfacing and had undergone the receiver bias of having selected out a surgeon and an operation that they felt would benefit them, there were some significant advantages. In Lavigne’s randomized, prospective study, there was no difference between either operative groups. In a similar study by Killampalli there were no differences in the level of function, and, interestingly, no differences in the level of activity pursued.”
“In a study by Mont, the outcomes were significantly comparable in terms of satisfaction and activity score, with a slight bias towards a higher activity score in the resurfacing patients. In a meta-analysis by Singer the femoral revision rate was twice that with resurfacing as with total hip. Robert also mentioned the Australian registry; I would agree that in young men, and in the hands of well trained, experienced surgeons, with large diameter acetabular components, the operation is comparable to total hip replacement. It is not better than total hip replacement. When taken in aggregate, the revision rate for resurfacing in every registry study shows that resurfacing does worse than total hip replacement.”
“In Graves’ multinational assessment of the three largest registries (England and Wales, Australia, New Zealand) it is confirmed by all that with the exception of young men with large diameter femoral heads, the revision rate is significantly higher. Robert published a study with Della Valle where they had a 7.5% failure rate with 40 adverse events. The complication rate was higher in patients over 55 and in females. My study found the same thing, with an 8% failure rate, including infection, femoral neck fractures, and loosenings of both the femoral and acetabular components. In our early experience we were concerned, and limited our use of this procedure to young men.”
“I think it’s indisputable that the broadest indications, the most reliable results, the least risk of an early reoperation, and the lowest risk of late mysterious complications, is with crosslinked polyethylene and a total hip replacement with a stem and an acetabular component.”
Moderator Thornhill: “Keith, is it an arrow that you should have in your quiver for some patients?”
Dr. Berend: “In my quiver, no, because the indications are so limited that you’re better off pulling the correct operation out of your bag every time and getting a good result nearly every time. The indications are clear: you must have bigger than a 54mm component, it must be well placed, and it needs to be a male patient under 55. Even with those patients, I’m still concerned about the second decade issues of metal-metal, and the fact that there is probably going to be a latency period. We’re not seeing it early because these are patients that have well positioned components that have a large diameter. But we may see it late. They all have high levels of ions, and they are going to have extraordinarily high levels of ions in the joint itself.”
Moderator Thornhill: “Who should get surface replacement?”
Dr. Barrack: “Males with osteoarthritis that are under 55 and want to be very active (doing activities that most total hip surgeons don’t recommend for their total hip patients). In the last American Association of Hip and Knee Surgeons (AAHKS) survey 80% of hip surgeons either advise or prohibit their patients from impact activities. There’s no evidence that at 10-15 years that this is detrimental for hip resurfacing.”
Moderator Thornhill: “Robert, is there an indication for this in women?”
Dr. Barrack: “It’s rare; it’s an issue of size and morphology.”
Moderator Thornhill: “Keith, Robert said the data show that this is a high activity implant (SRA). Do you agree?”
Dr. Berend: “There is no evidence that high activity levels are not obtainable nor are they bad in the second decade for a conventional total hip replacement. I’m in the 20% of surgeons in the AAHKS survey that don’t restrict their patients. There’s no data to the contrary.”
Dr. Barrack: “You just heard the data to the contrary, and 200 of them were from your older brother. The statistical significance was so high that the high activity level data is supported.”
Dr. Berend: “Those were patients that had already had the operation—meaning that they selected out a surgeon and an operation, and they met the criteria to have an operation…they felt like they were special. It isn’t that the total hips were told they couldn’t run, it’s that the resurfacings had that operation specifically because they felt like they could run…and afterwards they could run.”
Moderator Thornhill: “Boys, hang on! Robert, leg length discrepancy, limb and thigh pain…is that only in the first 6-12 months?”
Dr. Barrack: “These patients were 1-3 years out. Limb length has bias because it is a contraindication. But a patient saying they limp more or are less likely to walk 30 minutes…I don’t think you can attribute that to selection bias.”
Moderator Thornhill: “Thank you both.”
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