SLR - July 2020 - Joshua P. Manning

Isolated Subtalar Arthrodesis for Avascular Necrosis of the Talus

Reference: Dekker TJ, Pellegrini MJ, Schiff AP, et al. Isolated Subtalar Arthrodesis for Avascular Necrosis of the Talus. J Surg Orthop Adv. 2019;28(2):132-136.

Scientific Literature Review

Reviewed By: Joshua P. Manning, DPM
Residency Program: Mount Auburn Hospital – Cambridge, MA 

Podiatric Relevance: Avascular necrosis of the talus is a debilitating condition that causes pain, decreased function and potential arthritis. There are several causes of avascular necrosis of the talus including trauma, chronic steroid use, genetic conditions, and idiopathic causes. Most current literature focuses on tibiotalar arthrodesis or tibiotalocalcaneal arthrodesis for operative treatment of talar avascular necrosis. This study reviews 12 cases of isolated subtalar joint arthrodesis due to avascular necrosis of the talus and a subsequent symptomatic subtalar joint; the primary aim was to determine whether union could be achieved and if the etiology of avascular necrosis is prognostic for patient outcome following the procedure. 

Methods: A level IV retrospective cohort study was performed at a single institution identifying patients who underwent isolated subtalar joint arthrodesis and were followed until union due to AVN of the talus and primarily symptomatic subtalar joint arthritis. A total of 12 patients were identified. Records were used to determine the etiology of the avascular necrosis, demographic data, comorbidities, fixation methods, and biologics used in the surgery. Amount of tibiotalar arthritis pre-operatively and at last follow up was recorded using Kellgren and Lawrence grades for all patients. Subtalar fusion was assessed by radiographic bridging seen in plain film x-rays and CT scans, absence of radiographic nonunion signs, intact fixation, and a pain level of 0/10. Secondary outcomes were patient satisfaction, complications and reoperations. 

Results: Of the 12 patients, the etiology of avascular necrosis was trauma in six patients (five talar fractures and one subtalar dislocation) and atraumatic causes in the remaining six (two chronic steroid use, one inflammatory arthritis, one alcohol use, and two idiopathic). The traumatic group had a significantly higher Kellgren and Lawrence grade at the time of subtalar arthrodesis (p = .03). All 12 patients had successful subtalar fusion. 5/6 patients with traumatic etiology went on to have a major second operation, and only 1/6 patients with atraumatic causes required reoperation (p < .05). All reoperations were due to pain or progression of arthritis at the tibiotalar joint. All patients with a talar fracture required reoperation. 

Conclusions: Subtalar arthrodesis is possible with talar avascular necrosis. However, clinical success may not be achieved from subtalar fusion alone in patients with avascular necrosis due to talar fractures. In contrast, patients with atraumatic avascular necrosis can have both successful fusion and clinical success if treated with isolated subtalar arthrodesis. The increased preoperative tibiotalar joint arthritis in the traumatic group is a possible confounding variable, and there are other limitations such as retrospective study design and selection bias, but from this study the authors recommend isolated subtalar joint fusion in atraumatic avascular necrosis without tibiotalar arthritis. 

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