Learning Curve for Open Reduction and Internal Fixation of Displaced Intra-articular Calcaneal Fracture by Extensile Lateral Approach Using the Cumulative Summation Control Chart

Background: Open reduction and internal fixation (ORIF) of displaced intra-articular calcaneal fracture (DIACF) by extensile lateral approach is widely used but is technically challenging. In this study, the learning curve for ORIF of DIACF by extensile lateral approach was investigated. Methods: Between March 2014 and July 2018, 45 cases consisting of 40 patients underwent operative treatment for DIACF by the extensile lateral approach performed in all instances by a single surgeon. A moving average and cumulative summation control chart (CUSUM) were used for learning curve analyses. Operative failure was defined when at least 1 of the following parameters were unsatisfactory: reduction of Gissane angle and Bohler angle, posterior facet congruency, calcaneal width, subfibular impingement, axial alignment, or calcaneocuboid joint congruency. Results: The mean operating time was 117.4 minutes. Regarding the quality of reduction, the mean preoperative sum of the 7 parameters was 5.1 and improved to 0.6 postoperatively. The CUSUM for operative success peaked in the 20th case. The CUSUM and moving average graphics of operating time peaked at the 9th case and registered nadirs at the 34th case, with slight ascent and decent. The operating time for 20 cases in phase 1 (1-20) and for 25 cases in phase 2 (21-45) of the learning curve did not differ significantly. There was no statistical difference in the severity of fracture pattern. By comparison, in phase 2, patients showed a significantly better postoperative reduction quality. Conclusion: As indicated by multidimensional statistical analyses, primary technical competence in improving the reduction quality of DIACF was achieved after the initial learning period with 20 cases. After the learning curve for ORIF of DIACF, a better reduction quality in the sum of reduction parameters was observed.