Patient-specific instrument-assisted minimally invasive internal fixation of calcaneal fracture for rapid and accurate execution of a preoperative plan: A retrospective study

Background Traditional methods for minimally invasive internal fixation (MIIF) of calcaneal fractures require extensive intraoperative fluoroscopy, and fracture recovery is usually not ideal. We developed a new surgical procedure using digital surgical simulation and constructed a patient-specific instrument (PSI) for calcaneal fracture that we used during the operation. This study investigated whether PSI-assisted MIIF of calcaneal fracture enables rapid and accurate execution of the preoperative plan. Methods We retrospectively analyzed patients with Sanders type III or IV fresh calcaneal fractures who had undergone PSI-assisted MIIF at our hospital from January 2016 to December 2018. We analyzed perioperative data including intraoperative fluoroscopy time, concurrence of internal fixation actual usage (IFAU) with the preoperative plan, surgery time, and complications. We also compared pre- and postoperative actual measurements from X-ray radiographs and computed tomography images including Böhler, Gissane, and calcaneus valgus angles; subtalar joint width; and calcaneal volume overlap ratio with the preoperative design. All patients had been followed up and their American Orthopedic Foot and Ankle Score (AOFAS) score was available. Results Mean intraoperative fluoroscopy time was 3.95 ± 1.78 h; IFAU in 16 patients (16 ft) was the same as the preoperative plan; mean surgery time was 28.16 ± 10.70 min; and none of the patients developed complications. Böhler, Gissane, and calcaneus valgus angles and subtalar joint width did not differ between pre- and postoperative plans; however, the actual preoperative values of each of these parameters differed significantly from those measured postoperatively. The calcaneal volume overlap ratio with the preoperative design was 91.2% ± 2.3%. AOFAS scores increased with time, with significant differences in the score at each time point. Conclusions The newly developed PSI-assisted calcaneal fracture MIIF method can rapidly and accurately execute the preoperative plan.