Reconstruction of talus model with Mimics software for treatment of talar posterior process fracture through posteromedial malleolar approach

Abstract

Objective To evaluate the advantages of reconstructing by mimics software before operation a three-dimensional model of talar posterior process fracture which is to be used in the treatment of talar posterior process fracture through the posteromedial malleolar approach. Methods From May 2015 to February 2019, 7 patients with talar posterior process fracture were treated at Department of Orthopaedic Trauma, Jishuitan Hospital. They were 5 men and 2 women, aged from 20 to 70 years (mean, 39 years). They underwent routine CT examination preoperatively. Their posterior process of talus was reconstructed by Mimics software based on their CT scanning data before operation to determine the size, number and displacement of fracture fragments. Their fractures of posterior process of talus were treated by open reduction and screw fixation in prone position through the posterior ankle approach. The American Orthopedic Foot & Ankle Society (AOFAS) ankle-hindfoot scoring system was used to evaluate functional recovery. Results The operation time for this group ranged from 70 min to 105 min, averaging 87.1 min. Early after operation, the wounds healed well with no injury to nerves or tendons. All patients were followed up for 4 to 24 months (average, 12 months). Follow-up by X-ray examination after 10 to 16 weeks revealed fracture union with no complications like screw breakage, nonunion, malunion or traumatic arthritis. Their AOFAS ankle-hindfoot scores at the final follow-up ranged from 80 to 98 points. Conclusion Preoperative three-dimensional reconstruction of talar posterior process fracture based on CT images using Mimics software can accurately determine the entry point and direction of screw insertion, yielding advantages of clear exposure, easy reduction and convenient screwing in the treatment of talar posterior process fracture through the posteromedial malleolar approach. Key words: Talus; Os trigonum; Fractures, bone; Materialise’s interactive medical image control system; Surgical approach