Complication Rates of Open Subtalar Fusion with and Without Combined Calcaneal Osteotomy in Severe Hindfoot Deformity

Category: Hindfoot; Ankle Arthritis Introduction/Purpose: Subtalar arthrodesis (STA) is a common procedure used to correct rigid, arthritic hindfoot deformity. The deformity is often able to be corrected through the subtalar arthrodesis-site, however in severe deformity, calcaneal osteotomy (CO) may also be required to realign the hindfoot. CO may predispose the patient to additional risk of wound complication due to the proximity of sinus tarsi and open lateral calcaneal osteotomy incisions. Despite the relatively common nature of hindfoot deformity, there is no study to date assessing the complication profile and outcomes of combined STA and CO when compared STA alone. The purpose of this study was to compare STA alone versus STA and CO to examine union rates and complications for a procedure with known nonunion risk. Methods: A retrospective review of all STA performed two institutions between January 2011 and August 2021 was performed. All STA performed during that time period were identified using a CPT code search and chart review. 22 patients were identified with combined STA and CO as part of a simultaneous procedure. We then performed a matched pair analysis for STA only as a control group identifying 22 patients with STA only. Complications including delayed union or nonunion, removal of hardware, wound complications, and the need for revision surgery were recorded. The two groups were matched for age, gender, presence of diabetes, and smoking status. Differences were analyzed using a two-tailed Fisher’s exact test. Results: There were 22 patients in the STA and CO group with 22 included matched pairs as our control group . There were no significant statistical differences between the two groups when comparing for age and comorbidities. The STA group had 4 recorded complications, while the STA and CO group had 1 recorded complication in the follow-up period. There was no significant difference in complications between the STA and the combined STA and CO group (p= 0.6361). Radiographic union was identified with CT scan. All but 1 patient achieved union in the STA and CO group (nonunion ST only and not CO). 0 nonunions were identified in the STA control group. Post hoc power analysis demonstrates 81% power regarding union compared to historical controls. Conclusion: There was no statistically significant increase in complications when a calcaneal osteotomy was performed in addition to a subtalar arthrodesis, with no specific concern for wound complication. This data supports that performing a calcaneal osteotomy in combination with a subtalar arthrodesis may be utilized to prevent undercorrection of hindfoot deformity without additional wound complication risk. This study is limited by small study groups due to the severity of deformity required to have an additional calcaneus osteotomy. However it also highlights the importance of deformity correction as no additional risk of revision surgery was added