How To Perform An Isolated Subtalar Joint Arthrodesis

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By Douglas K. Blacklidge, DPM

In regard to arthrodesis of the talocalcaneal joint, one should ensure supine positioning of the patient. Rotate the entire extremity internally with support at the ipsilateral hip to maintain the position, directing the toes toward the ceiling. The foot should extend beyond the operating table from about the ankle level. This positioning facilitates intraoperative fluoroscopy and alignment assessment.
A thigh tourniquet is routinely in place with this procedure but one usually only needs this to be inflated for a portion of the procedure. For most rearfoot/ankle reconstructive procedures, we inflate the tourniquet prior to preparing the joint surfaces for arthrodesis. We generally deflate the tourniquet prior to closure. The practice of not using the tourniquet during soft tissue dissection and closure encourages more meticulous hemostasis and leads to less postoperative bleeding, swelling and their associated complications. An alternative to this practice would be utilizing a postoperative drain.
The surgeon would most commonly perform the procedure for isolated subtalar arthrodesis through a lateral incision. However, in some cases such as severe valgus, a medial incision works well. When one is using the procedure to realign a medial facet subtalar coalition, a medial incision provides better opportunity to resect the coalition and provide realignment. Visualization of the posterior facet surfaces is better from a lateral incision than from a medial incision. The lateral incision allows access to the posterior talocalcaneal articulation as well as the medial talocalcaneal articulation for joint preparation.
I prefer making an incision from just distal to the lateral malleolus, extending distally along the floor of the sinus tarsi and stopping at the anterior process of the calcaneus. If one opts for a medial incision, it should be from posterior to anterior directly over the medial facet of the talocalcaneal joint, just as one would approach a medial facet coalition resection. This incision leads to retraction of the tibialis posterior tendon superiorly and the flexor hallucis longus tendon is inferior to the sustentaculum tali.
The exposure for joint preparation requires the release of the ligamentous structures about the talocalcaneal articulation. Through the lateral incision, elevate the extensor digitorum brevis from the floor of the sinus tarsi and do the same for the interosseous talocalcaneal ligament. Preserve the soft tissues attached to the plantar talar neck. Releasing the soft tissues of the sinus tarsi from the calcaneus and elevating them with the talus preserves the lateral vascular supply to the talus.
Release the calcaneofibular ligament and release the talocalcaneal capsule to gain access to the joints. If one is using a medial approach through the superficial deltoid ligament, release the same soft tissue structures with the exception of the extensor digitorum brevis and calcaneofibular ligament.
After releasing all ligamentous structures and visualizing the joints, use a lamina spreader to distract the posterior subtalar articulation. This facilitates joint surface preparation. Surgeons routinely use osteotomes and bone curettes to remove any articular cartilage down to healthy subchondral bone. At this point, irrigate the surgical site prior to preparing the subchondral bone. Proceed to fenestrate the bone surfaces aggressively with a 2-mm drill bit and score the bone surfaces with a saw or osteotome. This step must be aggressive to break up the subchondral cortical bone plates and encourage bone union across the joint.

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