3D Printed Models Improve Surgical Planning for Correction of Severe Postburn Ankle Contracture With External Fixator

Abstract

Background: Gradual distraction with external fixators such as Ilizarov frame has been widely used for the treatment of severe postburn ankle contracture (PAC). However, the application of external fixator is complex and conventional surgical planning based on 2D imaging is compromised due to a lack of spatial geometry and tactile feedback. The purpose of this study was to evaluate the surgical planning with patient-specific 3D-printed models (3DPM) for the treatment of PAC with external fixators. Methods: A two-centered retrospective cohort study, composed of consecutive patients who underwent external fixation for the treatment of severe PAC, was implemented. Patients were divided into two cohorts (3DPM group vs. Control group) according to whether 3DPM was used for preoperative surgical planning. The primary outcome variable was operation duration. Other outcome variables included improvement in metatarsal-tibial angle (MTA), range of motion (ROM), American Orthopedic Foot and Ankle Society (AOFAS) scores, and complications. Results: Between January 2008 and June 2018, ten patients with an average age of 23.8±14.1 yeas were treated for PAC at two centers. 3DPM were used for surgical planning in 5 patients. 3DPM group had significantly shorter operation duration than the control group (2±0.3 hours vs. 3.2±0.3 hours, p=0.0001). The comparison of preoperative, after removal of external fixator, and follow-up MTA, ROM, and AOFAS between the 3DPM and control group showed no significant differences. A plantigrade foot was achieved and gait was substantially improved in all patients at the final follow-up. Pin-tract infections occurred in 2 patients (one in each group) during distraction and were treated with wound care and oral antibiotics. Conclusion: The results of this study show that surgical planning using patient-specific 3DPM significantly reduced the operation duration while providing similar improvements in MTA, ROM, and AOFAS scores compared to traditional surgical planning for the correction of severe PAC with external fixators.