tile classification tile classification the tile classification is a system of categorizing pelvic fractures based on fracture pattern, allowing judgment on the stability of the pelvic ring. classification tile classification 1 2 3 a - stable innominate bone avulsion or wing fracture stable ring fracture with intact posterior arch denis iii transverse sacral fracture b - rotationally unstable/vertically stable open-book external rotation injury young-burgess lateral compression type internal rotation injury bilateral c - rotationally and vertically unstable unilateral with intact contralateral side unilateral with incomplete contralateral side bilateral