Why We Need Dual-Mobility Bearings for THA
Large-diameter femoral heads have been used as one option for decreasing the likelihood of dislocation after total hip arhroplasty (THA), and they have been effective. However, they have some downsides:
- They are mainly useful for patients with intact abductors, not for those with abductor insufficiency.
- They are metal, and have been associated with mechanically assisted crevice corrosion.
At the ICJR San Diego Course, R. Michael Meneghini, MD, from the Indiana University School of Medicine, Indianapolis, Indiana, shared his insights on another strategy that is an alternative to constrained liners and large metal heads: dual-mobility bearings.
Dual-mobility bearings consist of a highly cross-linked polyethylene ball and a porous metal acetabular component – the opposite of what orthopaedic surgeons are used to with other bearings and liners. Because the dual-mobility bearings have been used and studied in Europe for decades, information about their long-term efficacy is available. One study followed 384 patients with dual mobility bearings for a mean of 15 years. There were no early or late hip dislocations.
A small number of patients in the study experienced wear, intra-prosthetic dislocation, and cup loosening. Dr. Meneghini noted that the bearings and liners used in the study were different from those used today: The liners were made of stainless steel, and the 22-mm bearings had a porous alumina coating. Despite the design issues, there was a 96% cup survivorship at 18 years and an 89% prosthesis survivorship at 15 years.
Dr. Meneghini said that overall, dual-mobility bearings have an established track record, as well as a solid biomechanical basis for improving hip stability and reducing the risk of dislocation.
Click the image above to watch Dr. Meneghini’s presentation.