A Closer Look At The Future Of Total Ankle Arthroplasty
- Volume 22 - Issue 5 - May 2009
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These systems rely on three separate components for the ankle joint rather than two components. The tibial and talar components remain, but rather than these components having contact, there is a third polyethylene insert (called the mobile bearing) between these components to allow for freedom of translation and rotation.
Normal biomechanics of the ankle cause shear forces on the classic two-component systems. This shear leads to accelerated breakdown of the polyethylene inserts and high amounts of stress at the osseous component interface, which can ultimately result in failure of the device.
With the inclusion of a fully replaceable mobile bearing in the design of these implants, the prevailing thinking is there will be less stress passing through the prosthesis and its osseous interface. In turn, this will hopefully lead to a longer life for the device. Furthermore, allowing for translation and rotation should allow for more natural ambulation for the patient.
Total ankle implants are becoming more widely used by podiatric surgeons in the U.S. and abroad. With a better understanding of biomechanics and learning from previous failures and successes in total joint replacement implants in other areas of the body, perhaps the total ankle implant may soon become the procedure of choice for chronic ankle conditions as opposed to arthrodesis.
Dr. Johnson is a first-year resident at the Hennepin County Medical Center in Minneapolis.
Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons, and is board-certified in foot and ankle surgery. He is in private practice in Little Rock, Ark.
For further reading, see “A New Solution For The Arthritic Ankle” in the December 2005 issue, “Inside Insights On Ankle Replacement Surgery” in the March 2008 issue, “Total Ankle Arthroplasty: Do The Risks Decrease With Experience?” in the July 2006 issue and “Are Ankle Implants Worth Another Look?” in the April 2003 issue of Podiatry Today.
To check out the archives or get information on reprints, visit the Web site at www.podiatrytoday.com.
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