Patient-specific instrument assisted calcaneal fracture minimally invasive internal fixation can carry out preoperative plan accurately and quickly: a retrospective study

Abstract Background: Almost all of the traditional calcaneal fracture minimally invasive internal fixations (MIIF) require a lot of intraoperative fluoroscopy, moreover, the fracture recovery of many patients is not considered ideal. Therefore, we designed a new surgical procedure through the digital surgical simulation and made patient-specific instrument (PSI) for calcaneal fracture patients before surgery, and then we manage the operation through the assistance of PSI during the whole process. The purpose of this study is to verify whether the PSI assisted calcaneal fracture minimally invasive internal fixation can carry out preoperative plan accurately and quickly. Methods: We retrospectively analyzed the Sanders type III or IV fresh calcaneal fracture patients who had been performed MIIF assisted by the PSI in our hospital during January 2016 to December 2018. We collected and analyzed perioperative data including intraoperative fluoroscopy times, whether the internal fixation actual usage (IFAU) same as preoperative plan, surgical time and situation of complication; and collected and analyzed the data of preoperative actual measurement, preoperative-plan and postoperative actual measurement from X-rays and CT, including Böhler angle, Gissane angle, subtalar joint width, calcaneus valgus angle and calcaneal volume overlapping ratio. All patients had been followed up and their AOFAS score had been recorded. Then we performed statistical analyses. Results: The intraoperative fluoroscopy times was 3.95±1.78, the condition of IFAU in 16 patients (16 feet) was the same as preoperative plan, the surgery time was 28.16±10.70 min, no patients developed complications. The preoperative plan Böhler angle, Gissane angle, subtalar joint width and calcaneus valgus angle were not significant different from the postoperative; the preoperative Böhler angle, Gissane angle, subtalar joint width and calcaneus valgus angle were all significant different from the postoperative. The calcaneal volume overlapping ratio with preoperative design was 91.2±2.3%. The AOFAS score of all patients gradually increased as time goes on, and difference of the AOFAS scores between all time-points were significant. Conclusions: The new patient-specific instrument assisted calcaneal fracture minimally invasive internal fixation can carry out the preoperative plan accurately and quickly.