Coincidence test with 3D mirror image of unaffected side used for contralateral calcaneal fracture / 中华创伤骨科杂志

ABSTRACT

Objective:To evaluate the clinical significance of the coincidence test with 3D mirror image of unaffected side in the treatment of contralateral calcaneal fracture.Methods:A retrospective analysis was performed of the 35 patients who had been treated for single calcaneal fracture by coincidence test with 3D mirror image of unaffected side from January 2016 to June 2018 at Department of Trauma Orthopedics, The Sixth Hospital of Ningbo. They were 29 males and 6 females with an average age of 44 years (from 18 to 71 years). By Sanders classification, 19 cases were type Ⅱ and 16 cases type Ⅲ. CT scan and reconstruction of both calcaneuses was performed. The image of unaffected calcaneus was mirrored by Mimics software to guide virtual treatment of contralateral calcaneal fracture. Preoperatively the virtual bilateral calcaneuses and the reduced calcaneus were 3D printed to guide the actual operation. The coincidence test with 3D mirror image of unaffected side was used to evaluate fracture reduction after operation. Postoperative parameters such as B?hler Angle, Gissane Angle, calcaneal width, and coincidence of the affected calcaneal bone were recorded at 12 months after surgery. The clinical outcomes were assessed by American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and visual analogue scale (VAS) score.Results:In this cohort, operation time averaged 43.9 min (from 30 to 55 min), time from admission to operation 3.6 d (from 0 to 14 d), and hospital stay 6.3 d (from 3 to 11 d). The patients were followed up for an average of 18.8 months (from 13 to 24 months). All patients achieved bone union after an average of 17 weeks (from 12 to 26 weeks). Re-collapse of subtalar articular surface, talocalcaneal joint fusion, loss of calcaneal height or length, and calcaneal width increase were observed in none of the patients. The VAS scores averaged 2 (from 0 to 4), and the AOFAS scores 93.3 (from 76 to 98). The total coincidence was 95.2%±3.5%. Spearman test indicated a positive correlation between postoperative total coincidence and AOFAS score ( ρ=0.588, P<0.05). Conclusion:The coincidence test with 3D mirror image of unaffected side can be used to treat contralateral calcaneal fracture, with advantages of reduced surgical time, increased surgical accuracy and fine clinical outcomes.