ICJR DEBATES: Dual Mobility Cups Are the Way of the Future
Dr. Raymond Kim and Dr. Thomas Schmalzried go head-to-head over the issue of using dual mobility cups to reduce the risk of instability in total hip arthroplasty patients.
Instability is the most common reason for revision total hip arthroplasty (THA) – it’s responsible for nearly a quarter of these procedures.
One of the strategies for optimizing stability is the use of a larger-diameter femoral heads, but there are tradeoffs, including thinner polyethylene liners, the potential for fatigue failure, and the possibility of taper corrosion.
Raymond H. Kim, MD, from Colorado Joint Replacement in Denver, sees the use of dual mobility bearings, particularly in patients at higher risk for instability, as an alternative to using larger femoral heads.
He argued in favor of dual mobility bearing in a debate with Thomas P. Schmalzried, MD, of St. Vincent Medical Center in Los Angeles, California, at ICJR’s 3rd Annual Pan Pacific Orthopaedic Congress.
Dr. Kim said outcomes research has shown that the use of dual mobility bearings decreases instability compared with conventional implants, and he has adopted their use in his practice for complex primary THAs in patients at high risk for instability, as well as for the following revision THAs:
- Difficult instability revision cases
- Inability to use a 36-mm femoral head due to a small cup size
- Abductor deficiency
- Conversion from a metal-on-metal implant
Dr. Schmalzried agreed that dual mobility bearings are appropriate for a very select group of patients. But he believes there are other ways to reduce instability, chief among them improved surgical technique – which he said is the most cost-effective solution to dislocation in primary THA.
For example, he said surgeons should critically look at component positioning of their past THA patients to understand where they typically place components and how they could improve the placement. He’s also a proponent of using digital imaging intraoperatively to confirm component positioning.
He also noted that dual mobility bearings are more expensive than more conventional bearings, which is a consideration in the current healthcare environment. However, he said, in the case of a revision procedure in a high-risk patient, the additional cost can be rationalized.