Use of 3D modelling and 3D printing for the diagnostic process, decision making and preoperative planning of periprosthetic acetabular fractures.

Periprosthetic acetabular fractures represent an uncommon but challenging complication of total hip arthroplasty (THA), mostly related to low-energy trauma and pathological conditions that reduce bone quality. Therefore, particularly in elderly patients, these fractures are associated with periprosthetic osteolysis and bone loss. CT scan is considered the gold standard to define the fracture pattern; however, the presence of the prosthetic implants in situ limits the full view of the articular surface and bone loss. A three-dimensional (3D) modelling software allows precise tridimensional reconstructions of the bony surface, virtually removing the metallic implants trough DICOM image segmentation. We highlight the case of a periprosthetic acetabular fracture around THA which occurred to a 75-year-old woman, in which a 3D modelling software was used to improve the assessment of fracture morphology and bone quality. Moreover, the 3D images were printed in a real-life size model and were used for preoperative implant templating, sizing and surgical simulation.