Prevalence and characteristics of tarsal coalition in East Asians: what are the differences compared to Caucasians?

Abstract Background Previous studies have reported a prevalence of tarsal coalition of 1–2%. Calcaneonavicular coalition is known as main anatomical type. The bilateral occurrence of tarsal coalition is known to be 50–60%. These are the results of studies on Caucasians, there have been few studies targeting large number of East Asians so far. Also, there are not many analyzes of tarsal coalition on both feet especially in East Asia. This study was performed to evaluate the prevalence and characteristics of tarsal coalition in the Korean population using both-side computed tomography. We hypothesized that the prevalence and characteristics of tarsal coalition in East Asians might differ from previously reported results from Caucasians. Methods The medical records of 839 patients who underwent bilateral computed tomography on foot and ankle in our hospital from January 2012 to April 2021 were reviewed. Fifty received a diagnosis of tarsal coalition. The overall prevalence of tarsal coalition and proportions of tarsal coalition patients by gender and age were assessed. Anatomical types of tarsal coalition were classified according to union locations and bilateral occurrence was evaluated for each anatomical type. In addition, proportions of symptomatic patients associated with tarsal coalition were evaluated by anatomical type. Results The overall prevalence of tarsal coalition among the 839 patients was 6.0%. Isolated talocalcaneal coalition was the most common anatomical type (50.0%). Bilateral occurrence was observed in 56.5% of those with tarsal coalition, talocalcaneal coalition had the highest bilateral occurrence (76.0%). Isolated union of the posterior facet was the most common subtype of talocalcaneal coalition (43.2%). Talocalcaneal coalition had a significantly higher proportion of symptomatic patients associated with tarsal coalition than calcaneonavicular coalition (p = 0.019). Conclusion The prevalence of tarsal coalition was found to be 6%. Talocalcaneal coalition was the most common, and most talocalcaneal coalitions involved the posterior facet. Talocalcaneal coalition was significantly more associated than CN coalition with bilaterality and coalition related symptoms. The possibility of tarsal coalition in foot and ankle patients in East Asians should always be considered, and bilateral examination is essential for diagnosis.