Fusion of three joints in the foot:

Talonavicular joint

Talocalcaneal joint

Calcaneocuboid joint

Fixation varies but is often with 6.5- or 7.0-mm cannulated screws for the STJ and two staples at 90° for the CC and TN joints. Hindfoot should be positioned in slight valgus position, about 5°. The body can compensate for valgus. Varus foot should be avoided at all cost; these patients end up with pain and callus formation under the lateral midfoot and forefoot. The TN fusion requires the longest time for revascularization. As a result of a triple arthrodesis, there is extra stress on the ankle joint. For this reason, the ankle joint should be free of DJD pre-op. Sliding the calcaneus posteriorly on the talus will raise the arch, and sliding the calcaneus anteriorly on the talus will lower the arch.

Subtalar joint arthroereisis implants are designed to limit subtalar joint pronation by blocking the anterior-inferior displacement of the talus. Although they are commonly referred to as subtalar joint implants, they are not inserted into the joint. They are inserted into the sinus tarsi between the posterior and middle facets of the STJ. The goal of STJ arthroereisis implants is to limit pronation and reduce heel valgus by blocking contact of the lateral talar process against the calcaneal sinus tarsi floor. They are sometimes described as an “implantable orthotic.” All subtalar implants are considered both “direct impact” and “axis-altering” implants. They are considered direct impact implants because the implants physically block the motion of the talus. This decreased motion alters the spatial orientation of the STJ axis during gait, making them “axis-altering” too.