CT scan-based 3D fracture mapping in civilian gunshot intracapsular fractures of the femur neck.

Introduction: Displaced intracapsular neck of femur (NOF) fractures secondary to civilian gunshots are rare injuries with universally poor outcomes following surgical fixation. No studies have been published on fracture mapping in NOF fractures secondary to civilian gunshots. Objectives: We performed CT scan-based fracture mapping to identify the most common fracture patterns in these injuries. Methods: Design: Retrospective search of prospectively collected data. Setting: Single Level 1 Trauma hospital. Patient selection criteria: All patients presenting with gunshot fractures to the femur neck between 01 January 2009 and 31 December 2022 were identified. Once identified from Picture Archiving and Communication System (PACS), computed tomography (CT) scans in Digital Imaging and Communication in Medicine (DICOM) format were imported into Mimics 16 software and fracture fragments were segmented and three-dimensional (3D) reconstruction was generated. The reduced fractures were exported to 3-Matic software to merge the fragments and adjust the orientation in three planes. An uninjured femur model was used as a template for reduction. Fracture lines and heat maps were then generated. Our outcome measures were successful mapping of the identified fracture lines. Results: A total of 25 intracapsular femur neck fractures were identified and suitable for CT scan mapping. All patients were male with an average age of 22 (range 18-32). Once generated, fracture maps were used to show the location, distribution and frequency of the fracture lines. In all but two cases the fracture line propagation remained within the confines of the hip joint capsule. In three cases there was fracture extension into the superior aspect of the femur head, and in one case extension into the inferior aspect. Conclusion: This is the first study to perform 3D fracture mapping for intracapsular femur neck fractures secondary to civilian gunshot injuries. The exercise has helped us better understand the commonest fracture patterns and assisted us with surgical planning and execution.