Keywords: Calcaneus Fracture, Post Traumatic Osteoarthritis, Subtalar Arthrodesis
Introduction/Purpose: Post-traumatic subtalar arthritis following calcaneal fractures often leads to pain, deformity, and functional impairment. While subtalar arthrodesis aims to address these symptoms, there is a risk of nonunion, with rates ranging from 10% to 24%. Factors such as poor bone quality, altered anatomy, and compromised vascularity may negatively impact fusion in this population. Limited data exists specifically examining successful fusion rates in patients with a history of calcaneal or talar fracture. The purpose of this study is to evaluate fusion rates following subtalar arthrodesis in patients with post-traumatic arthritis secondary to prior calcaneal and talar fractures and identify factors associated with nonunion. We hypothesized that a prior calcaneal fracture would be associated with lower fusion rates compared to other surgical indications.
Methods: A retrospective case-control study was conducted on adult patients who underwent subtalar arthrodesis (CPT 28725) at a tertiary referral center between January 1, 2014, and December 31, 2024. Patients with at least three months of follow-up and available postoperative imaging (X-ray or CT) were included. Only cases with a primary diagnosis of post-traumatic arthritis following talar or calcaneal fracture were analyzed. Exclusion criteria included additional ankle or hindfoot fusions, neuropathic arthropathy, or calcaneal osteotomies beyond medial displacement. Fusion was defined by CT evidence of >25% bony bridging or radiographic signs plus minimal pain and no hardware loosening per clinic notes. Demographic and operative data (e.g., screw type, biologic use) were recorded. Statistical analysis included Chi-Square and Fisher’s exact tests for categorical variables, and t-tests or Wilcoxon Rank Sum tests for continuous variables, as appropriate.
Results: Of 374 patients who underwent subtalar arthrodesis for all diagnoses, 326 (87.2%) achieved fusion. There were no significant differences in age, BMI, sex distribution, bone graft usage, biologic adjuncts, or screw types between fusion and non-fusion groups (p> 0.05 for all). A history of post-traumatic arthritis secondary to talus fracture was not associated with fusion outcomes (p>0.999). However, post traumatic arthritis secondary to calcaneus fracture was significantly more common among patients who did not achieve fusion (31.3%) compared to those who did (15.3%, OR 2.5, p=0.0066) (Table 1).
Conclusion: Subtalar arthrodesis demonstrated a high overall fusion rate, however, patients with post- traumatic arthritis secondary to calcaneal fractures had significantly higher nonunion risk. These findings suggest that prior calcaneal fracture is a key risk factor for nonunion and should be carefully considered in surgical planning and patient counseling.
