Learning Curve of Novice Foot and Ankle Surgeon on Minimal Invasive Calcaneus Surgery Using the Sinus Tarsi Approach

Background The sinus tarsi approach has gained popularity for treating calcaneal fractures; however, limited research exists on the learning curve among novice orthopedic surgeons. This study aimed to assess the learning curve of junior orthopedic surgeons who have recently completed their fellowship, focusing on surgical efficiency and clinical outcomes. Materials and Methods From October 2022 to January 2024, 50 cases of calcaneal fractures (12 Sanders type 2, 23 type 3, and 15 type 4) were treated using the sinus tarsi approach at a single Level 1 trauma center. The cumulative sum test was employed to identify case cutoffs for key surgical parameters. Pre- and postoperative X-rays and CT scans were analyzed to measure the Bohler angle, hindfoot varus angle, and posterior facet step-off. Operative time, intraoperative C-arm fluoroscopy use, and postoperative complications, including infections and revision surgeries, were also evaluated. Results Significant postoperative improvements were observed: the Bohler angle increased from 12.2° to 26.3°, hindfoot varus angle decreased from 15.2° to 5.3°, and posterior facet step-off was reduced from 14.1 mm to 0.56 mm. Satisfactory corrections of the Bohler angle and hindfoot varus angle were consistently achieved after 21 cases, while posterior facet step-off correction reached proficiency after 26 cases. Reduction quality was classified as Excellent (n = 24), Good (n = 13), Fair (n = 8), and Poor (n = 5), with Excellent or Good outcomes achieved consistently after 21 cases. The mean operative time was 104 minutes, decreasing from 124.2 minutes to 85.2 minutes after 24 cases. The average number of fluoroscopy shots was 141, decreasing from 206.4 in the first 19 cases to 95.1 thereafter. Complications included six revision surgeries, one infection, four cases of insufficient posterior facet correction, and one case of screw penetration. Conclusion Novice foot and ankle surgeons can achieve surgical proficiency in the sinus tarsi approach for calcaneal fracture fixation after approximately 20 to 26 cases. This learning curve is reflected in optimized operative time, reduced fluoroscopy use, and satisfactory radiographic correction of the Bohler angle, hindfoot varus angle, and posterior facet step-off. Level of Evidence: Level IV, Case series