Quadrilateral plate fractures of the acetabulum: Proposition for a novel classification system.

Background: Currently, there is no definition or classification system for quadrilateral plate (QLP) fractures; the aim was to anatomically and radiologically characterise the QLP, propose a definition and classify QLP fractures.

Methods: This study included an anatomical component and a radiological component. The anatomical study aimed at defining the characteristics of the QLP; the QLP was identified using four articulating bony pelvis specimens. A titanium mesh was placed on the specimens' quadrilateral surface; standard anteroposterior and oblique views were obtained, and axial CT images, to determine the radiological landmarks. The radiological study included the review of images of patients with QLP fractures; fractures involving the QLP were identified in a series of 609 consecutive patients with acetabular fractures.

Results: We considered QLP fractures where the QLP is separated from both columns of the acetabulum; this was found in 16% (98 cases). They were mostly encountered with associated both columns fractures (60 cases; 61%), Separation of the QLP could be complete or incomplete, or simple or comminuted, so QLP fractures were divided into three types: QLP1, simple with incomplete separation; QLP2, comminuted with incomplete separation; QLP3, comminuted with complete separation (QLP4), simple with complete separation.

Conclusion: The QLP was characterised, and a definition and classification system; Cairo University Hospitals (CUH) Classification was proposed for these fractures. We believe that this classification may prove useful in the future for the identification and management of these fractures.