How To Perform An Isolated Subtalar Joint Arthrodesis
Surgeons can perform isolated subtalar arthrodesis for a variety of conditions. The list of the most common indications includes: degenerative joint disease, talocalcaneal coalition, post-traumatic arthrosis, inflammatory arthropathy, valgus/varus deformity and hindfoot instability.
For an effective subtalar arthrodesis, proper alignment is essential for any of the indications.7,8 In most cases, one can achieve proper alignment by simple manipulation of the joint. Realignment of significant varus or valgus correction by manipulation alone is limited. Even with joint resection of the talocalcaneal articulation, correction of major hindfoot deformities is limited for an isolated arthrodesis. Movement of the calcaneus with respect to the talus may be the primary focus for realignment of the hindfoot but the calcaneocuboid and talonavicular relationship is affected by any change in position of the calcaneus. In cases of severe valgus or varus, triple arthrodesis would offer greater realignment potential.
Occasionally, surgeons may perform posterior calcaneal osteototmy in addition to an isolated subtalar arthrodesis to provide additional translation of the posterior calcaneus.9 Another unique situation is depression of the posterior facet of the talocalcaneal joint after an intraarticular calcaneal fracture. Hindfoot realignment often requires restoration of heel height via bone block distraction arthrodesis of the talocalcaneal joint.10,11
Preoperative evaluation must include consideration of the goals of the procedure to fuse the talocalcaneal joint. The importance of alignment cannot be overemphasized. The fusion position of the calcaneus with respect to the talus dictates function for the remainder of the foot, especially the midtarsal joint.
If the surgeon uses the procedure for controlling a valgoplanus foot, the subtalar joint would be positioned with the lateral process of the talus up and out of the floor of the sinus tarsi in a more supinated position. If you are utilizing the procedure to correct an over-supinated hindfoot, the opposite would be the case for positioning of the fusion. In the case of a fusion for a previous calcaneus fracture, the surgeon would be elevating the depressed posterior facet by an interpositional bone graft to restore a more anatomic relationship between the talus and calcaneus for the most functional fusion.10,11