Ensure that you have abundant exposure of the joint surfaces (Fig. 4.2). The joints of the hindfoot are curved and undulating. Lack of adequate distraction will likely compromise the removal of cartilage and the adequate preparation of the fusion surfaces.

Prepare the joints from deep to superficial to ensure that visualization is maintained throughout the process. When using an osteotome for joint preparation, use with care to prevent laceration of neurovascular and tendinous structures.

The optimal alignment of a hindfoot arthrodesis is with the heel in approximately 5° of valgus. The talonavicular joint should be aligned such that the forefoot can rest easily in a plantigrade position when the ankle is in a neutral position. If the calcaneocuboid joint is to be incorporated in the fusion, then care should be taken so that the lateral column of the foot is neither elevated nor prominent as a weight-bearing surface. Alignment of all of these components should be checked before provisional fixation is converted to final fixation.

Fixation can be gained with a number of different types of hardware, most commonly with screws. For cannulated screws placed across the subtalar joint, it is helpful to just breach the posterior facet with the guide wire prior to joint reduction to ensure that the guide wire’s trajectory will be satisfactory.

Although standard fixation for talonavicular fixation is at least one screw through the medial portion of the talus across the talonavicular joint and into the talar head and neck, I have found that the addition of a screw placed dorsally through the midsagittal portion of the navicular across the talonavicular joint, talar head, and then into the calcaneus provides excellent compression and stability (Fig. 4.1). In cases where the bone stock of the medial navicular is compromised, this screw position provides for a very stable construct. In placing the screw, care should be taken not to disrupt the deep peroneal nerve and the dorsalis pedis artery.

In cases where screw fixation is not possible or does not provide enough stability, the use of compression staples can provide stability for the construct. Staples can readily be used for talonavicular fusions as well as calcaneocuboid fusions. They can also provide adjunctive fixation for the subtalar joint .

Bone loss can pose a substantial problem when attempting to gain apposed bone surfaces and optimal alignment. These challenges can often be overcome by proper positioning of the joint and backfilling with cancellous graft if the defect is a few millimeters in depth or bulk auto/allograft if larger.

The incision is made from the tip of the lateral malleolus and directed distally to the base of the fourth metatarsal. After the skin incision has been made, great care is taken to find and protect the branches of the sural nerve. Care must also be taken not to damage the peroneus brevis tendon, as it may run in the inferior flap near the incision site. The incision is deepened down to the level of the anterior process of the calcaneus. The extensor digitorum brevis muscle has part of its origin on the dorsal lateral surface of the anterior process. This muscle should be lifted from inferior to superior as a unit from the anterior process, thereby exposing the sinus tarsi. Once the sinus tarsi is exposed, the fibrofatty tissue as well as ligamentous structures are removed with sharp dissection and the use of a rongeur. The joint capsule of the subtalar joint is then incised to allow distraction of the subtalar joint. Initially, some of the articular cartilage may need to be removed before distraction instruments can be inserted. A smooth laminar spreader is then inserted along the posterior facet of the subtalar joint, and distraction is applied. Any restraining capsular structures are incised. Soft tissue tethering may be present medially, and careful release of these with a 15 blade and Cobb elevators can be done. Great care must be taken to prevent damage to the medial neurovascular structures as well as the flexor hallucis longus tendon. Once approximately 1–1.5 cm of distraction is obtained, a toothed laminar spreader may be inserted. This allows for more stable distraction during joint preparation. The position of the laminar spreader should be alternated between the inferior talar neck and the posterior facet. This allows all of the articular cartilage to be removed from the three facets of the subtalar joint.

Once the articular cartilage has been completely removed, the subchondral bone may be prepared. This can be done with initial drilling with a 2.0 mm drill or a 2.0 mm burr. The subchondral bone is further prepared by fish scaling it with a small osteotome. Care should be taken to maintain the joint architecture while preparing the surfaces. This will allow for a more congruent fit when reduction and fixation of joint surfaces is done.