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2.3 MECHANICAL ENGINEERING, Medical engineering, 3. MEDICAL AND HEALTH SCIENCES, Orthopaedics
There are a wide range of different types of ankle replacements on the market today each with a
different mechanical design. Unfortunately the results of ankle replacements are not as good as hip
and knee replacements; this is due to the complexity of the ankle joint. In the early days of ankle
replacements some of the prosthetics only lasted 4 months. Recent developments have improved the
longevity of the replacements although, there are still many complications and failures of the
replacements, these include; the prosthetic components migrating into the bone, the components
failing due to stresses induced by the forces and the surgery itself i.e. the incision site.
This paper will analyse the documented medical failures of the replacements from a mechanical
engineering perspective. Three ankle prosthetics are investigated in this paper: the Buechel-Pappas,
the Scandinavian Total Ankle Replacement (STAR) and the Hintegra ankle replacement. Medical
publications are examined to isolate the mechanical failure mechanisms of the replacements and to
categorise and quantify these failures in engineering terms. These failures will include wear
complications and also dislocations of the prosthetic parts among other failures. The paper will conclude by comparing the mechanical reliability of the four prosthetics examined.
Thian, C., Tiernan, S., McEvoy, F., Flavin, R. ''An Engineering Evaluation of Ankle Prosthetics'', 2008, 25th International Manufacturing Conference, September, DIT. Dublin.