The evolution of ankle arthroplasty

The results of ankle arthroplasty have generally been disappointing compare d to other forms of arthroplasty. The present survey of results of ankle ar throplasty deals with the anatomical, the kinemasiological the biomechanica l and the biological features of the ankle joint. These features all seem i mportant prerequisites for a successful total ankle prosthesis design. From the study of the results displayed in the literature and those of my own s eries it can be stated that a modern ankle arthroplasty should respect the normal anatomy and kinemasiology. Biomechanically it should work as a norma l ankle joint i. e. cylindrical mobility, congruency and a possibility for normal torque within the ankle mortise. The prosthesis components should on ly be fixed in solid subchondral bone, and preferably without cement. Only compressible forces should act at the bone-prosthesis interface. The axis o f the ankle joint as well as of that of the hindfoot should be aligned to n ormal. Meticulous surgery and special guide instruments are absolute necess ities. Restoration of muscle power and gait postoperatively are essential f or a good and lasting result. The indication for ankle arthroplasty is main ly cases of osteoarthritis (primary or traumatic) and rheumatoid arthritis. Contraindications are talus necrosis, Charcot joints, extreme osteoporosis , severe arteriosclerosis, and Very aggressive arthritis. Mental disorders and neurological disorders may also be contraindications. Furthermore, the patients should agree not to perform sports involving jumping and running o r other ankle demanding activities. The average annual failure rate should not exceed 1 % if these recommendations are followed.