Characteristics of Multifragmentary Patellar Fractures: Three-dimensional Computed Tomography-based Fracture Mapping Study

Abstract

Limited literature is available regarding anatomic patterns of articular injuries in comminuted patellar fractures. The present study aimed to map the location and frequency of fracture lines on the coronal and sagittal planes of the articular surface in AO/OTA 34C3 fractures. The directions of the fracture lines from the CT scans of 66 multifragmentary patellar fractures were highlighted in the coronal plane of the articular surface and in the midsagittal plane. The images of all fractures were then oriented to fit and superimposed over a single template. The primary horizontal fracture lines were identified in 63 patients (95.4%) using coronal articular surface fracture mapping. The average value of the primary horizontal fracture line was located between the middle and inferior facets. The secondary horizontal fracture lines ran frequently on the inferior border of the articular facet (83.3%). The secondary vertical fracture lines created satellite fragments and were mostly located on the periphery of the bilateral facet. Sagittal fracture mapping of the primary and secondary horizontal fracture lines with the main coronal fracture line revealed a predominantly X-shaped fracture map. The presence of the free articular type of coronal split fragment was significantly related to inferior pole fractures (OR: 8.15, P = 0.01).