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Surgeons hopeful reliable solutions will emerge soon for THA dislocation
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CHICAGO — Internationally recognized total hip arthroplasty leaders addressed the problem of unstable hips after primary or revision THA during a symposium moderated by Paul E. Beaule, MD, of Ottawa, Ontario, at the American Academy of Orthopaedic Surgeons Annual Meeting, here. Panel members proposed and debated solutions for this postoperative complication and took a hard look at the roles that surgical approach, components and positioning play.
“Instability and dislocation continue to be problematic, especially for revision hip surgery as well as primary, and it is the most common reason for early revision surgery after primary total hip,” John C. Clohisy, MD, of Washington University, in St. Louis, said.
Symposium participants Robert T. Trousdale, MD, of Rochester, Minn., and Andrew J. Shimmin, MD, of Windsor, Australia, debated the merits of implant techniques, like hip navigation to improve long-term stability, while others proposed that large femoral heads and doing a better job of selecting patients for the procedure would be most efficacious.
Problematic posterior approach
Most surgeons in the audience use a posterior total hip arthroplasty (THA) approach, based on results of the audience response system, with the lateral Hardinge approach being the next most popular approach used.
However, Michael Leunig, MD, of the Schulthess Clinic in Zurich, noted there are higher dislocation rates with that approach.
“The posterior directional dislocation is by far the most usual dislocation route and the consequences are the approach compromises the posterior structures and may contribute to instability,” he said.
Surgeon experience and component design and positioning also can exacerbate THA dislocation problems.
Increased risk over time
In terms of ways to minimize THA instability — subluxation and dislocation — 75% of the audience indicated they believed acetabular component orientation was critical to a stable hip. But there is no one solution or cause of dislocation, Clohisy said.
“If you look at the literature, it is a bit difficult because there are multiple factors that influence the incidence of THA instability,” he said.
In the literature, Sir John Charnley, who studied early and late dislocators, found 3.2% dislocation rates in 185 hips. That same incidence emerged from a 1982 study of more than 10,000 THA patients done at the Mayo Clinic, and a later study out of the same institution conducted by Daniel J. Berry, MD, and colleagues, revealed cumulative THA dislocation risk over time, according to Clohisy.
“At 10 years, the risk was 3.8% and at 20 years 6%,” he said. “Recent research demonstrates the problem still exists.”
Reference:
Beaule PE. Symposium B: Worldwide perspective on hip instability after total hip replacement. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 19-23, 2013; Chicago.
Disclosures: Clohisy is a paid consultant to Biomet, Pivot Medical and receives research or institutional support from Wright Medical Technology and Zimmer. Leunig is a paid consultant to Smith & Nephew and has stock or stock options with Pivot.
Perspective
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Geert Meermans, MD
Dual mobility cups are often used and there is no evidence they are helpful and the long-term results not there yet. I think we should be careful in adopting these new techniques. In the past, we have come up with a couple of phases. It is interesting to see the new techniques. If you just look at the French already, doing about 30% of all the primary hips [with dual-mobility], I think that is a lot. I don’t think that is the proper solution for dislocation.
I think the use of bigger femoral heads is interesting. We are seeing less wear and less dislocation. That is one part of the solution, but I think the biggest issue would be to get better cup placement overall in all our patients. Probably we should leave the concept of a safe zone and go to the patient-specific anatomy and look at each patient, case by case, and see how we can get them in the right anteversion abduction angle. I think it would be a big challenge to see how we can manage them looking at pelvic tilting postoperatively and preoperatively…to get our cups on a patient-by-patient basis in a proper position. That would probably lead to less dislocation and hopefully we can solve the problem.
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