The artificial
ankle joint

Structure and function of the ankle joint

The ankle joint is made up of the bottom of the shinbone (or tibia) and the upper surface of one of the bones in the foot called the talus. The calfbone (or fibula), which runs along the outside of the tibia, is also part of the joint - providing stability along with the joint capsule, ligaments and muscles which surround the joint. In a healthy ankle the three bones (i.e. tibia, talus and fibula) mentioned are covered with smooth cartilage where they meet and form the joint. The capsule also seals the joint and produces a fluid which nourishes, lubricates as well as enables smooth, pain-free movement. Osteoarthritis, rheumatoid processes and trauma may damage and wear the cartilage. This wear is progressive and as such the joint becomes increasingly painful. Putting weight on it hurts more and walking distance reduces over time. Eventually even resting provides little relief from the pain.

The joint replacement

The TARIC® ankle system is a cementless „mobile bearing“ system. The two metal implants (i.e. the tibial component and the talar component) each have a pair of fins which are carefully wedged into place. The components have a special (commercially pure titanium and hydroxyapatite) coating which helps their fixation surfaces bond over time with the bones they are implanted onto / into - providing solid secondary fixation during the post-operative period. The system includes 5 sizes of tibial implant, 4 sizes of talar implant and a range of ultra high molecular weight polyethylene (UHMWPE) bearing inlays. The latter are highly congruent and have to mate with the talar component. Sophisticated instruments enable accurate extramedullary alignment of the tibial and talar resections. A drain (to manage wound secretions) may be inserted before closing the joint and carefully reconstructing the retinaculum with sutures.

Postoperative care

After the terminal cleaning of the joint a redon drainage is inserted in the joint and the capsule is closed with suture. Following the careful reconstruction of the retinaculum and the subcutane adaptation the skin can be closed with a stapler or conventional sutures.
The postoperative care may happen in Vacoped-shoe, which immediately can be released with an extension/flexion of 10-0-10°. For the first 3 weeks a partial weight bearing with 10-30 kg should take place. After 3 weeks the establishing of weight bearing can take place in a Vacoped-shoe. After radiological control the patient will be mobilised after 6 weeks without shoe under full weight bearing. Physiotherapy with active and passive exercises (e.g. CPM-splint) can take place from the first postoperative day for the whole process.