The Agility ankle prosthesis was designed by Dr.Frank Alvine was first inserted in a patient in 1984 and it was the first ankle replacement to receive FDA approval. It is used in the majority of ankle arthroplasties performed in the United States. It is a semi-constrained, two part prosthesis which resurfaces the medial, lateral and superior articular surfaces of the ankle joint.
It consists of a titanium tibial component with sintered titanium beads and a cobalt-chromium talar component with sintered cobalt-chromium beads. A modular polyethylene inserts locks into the tibial component. The first ankles were all constructed of titanium but since 1989 cobalt-chromium has been used due to loosening of two talar components in the first 3 years. Thicker tibial component was also used start from the first time due to two broken components in the first 21 ankles implanted.
The tibial articular surface is larger compared to the talar component as this will allow axial rotation. The problem with this was that during the axial rotation, incongruent articulation will take place on the articulating surface. On the other hand, during the dorsiflexion and plantarflexion, congruent articulation can be achieved. When Agility prosthesis is inserted, it is combined with an arthrodesis of the tibiofibular syndesmosis using one, or more, which commonly was two screws.