Crescent fractures of the pelvis treated by open reduction and internal fixation: a critique of Day's guidelines.

Assigning Day's classification to a given case can be difficult in up to 33% patients with crescent fractures due to the obliquity of the iliac fracture line in axial sections. Sacroiliac articular alignment is the primary factor determining the surgical approach. Besides the fracture configuration, additional factors like delay in surgery, locking of the fracture fragments, comminution of the iliac or sacral fragment as well as access to the additional injuries contribute to the decision making.