Background: This study aimed to create three-dimensional heat map and study the characteristic of fracture lines and represented fragments of OTA/AO type 43C pilon fractures.
Methods: CT scan was performed in105 fractures diagnosed with OTA/AO type 43C pilon fractures between January 2017 and December 2022. Three-dimensional pilon fracture maps were created and converted into fracture heat maps. CT scan graphic parameters including the fracture line height, α angle, β angle, the ratio of the area and size of bone fragment represented by the fracture line to the total articular surface were measured.
Results: The study included 105 patients with 91 males and 14 females. The fractures included C1 (n=16), C2 (n=23), and C3 (n=66). There was no statistically different among the most parameters except in the fracture-line height of the anterior fracture line (p=0.03) and the sagittal fracture line (p=0.02) between C2 and C3 pilon fractures. The average size of the anterolateral fragment, occupied approximately 13.5% of the articular surface area, was (11.5± 2.8) mm × (20.5± 6.3) mm with the average height of 29.8 mm. The average size of the posterolateral fragment, occupied approximately 13.0% of the articular surface area, was (15.7± 4.6) mm × (19.3± 4.0) mm with the average height of 19.1 mm.
Conclusion: This study demonstrates that the articular surface fracture lines in the C type pilon fracture are formed by fixed main fracture lines. The understand of morphological and distribution characteristics of the fracture lines and size of fragments in OTA/AO type 43C pilon fractures would help the surgeons take suitable approach and fixation.

Keywords: pilon fractures, heat map, three-dimensional reconstruction, classification