The study of broken quadrilateral surface in fractures of the acetabulum

Abstract

Purpose: Three-dimensional computerised tomography (3DCT) can provide comprehensive patho-anatomy of complex bone on a single image. Though important, the key articular quadrilateral [Q] surface has not been a part of the systems developed for classifying acetabulum fractures. The purpose of the study was to simplify the complexity of classification by the direct sign of the broken Q surface which lies opposite the entire floor of the acetabulum.

Methods: The study reviewed 84 acetabular fractures using 3DCT images of the interior lateral view (IL) taken between June 2002 to December 2009. Fractures were traditionally classified using the anatomical disruption, plane of the fracture line breaking through or not through the bone column described by Judet and Letournel.

Results: The 3D images clearly show the primary site of impaction acting on the acetabulum and the whole course of fracture. The image could not illustrate disruption of the lips of acetabulum and congruity of hip joints in 20 cases of wall (W) fracture. There were 30 transverse (T) fractures classified when the acetabulum was divided horizontally from front to back into upper and lower parts and 34 cases of column (C) fracture when the main vertical lines run and collide along the anterior and posterior column.

Conclusions: This study showed that the well-known complex fractures can be satisfactorily classified with the broad flat inner plane of the Q surface.

Fig. 1

a The whole column of innominate bone resembles the inverted modern English Y letter. The iliac wing stands for the forked holder connecting with the component of the anterior and posterior columns. b The thin flat quadrilateral surface lies just opposite the floor of acetabulum

Fig. 2

The images of interior lateral (IL) view (a) and exterior lateral view (b) clearly show boundaries and dimensions of the inner and outer sides of the ilium bone, respectively. Fracture lines splitting the whole ilium can be better verified on IL view

Fig. 3

Pure T fracture of left acetabulum in the interior lateral (IL) view (a) shows incomplete transverse fracture line not emerging through the Q surface. IL view (b) shows complete transverse fracture line emerging through the Q surface into the posterior column. The IL views C1–3 show more severe T- or Y-shaped fractures by secondary fracture line(s)

Fig. 4

a Less severe C fracture, 3D AP image (A₁) shows left central hip dislocation. Interior lateral (IL) view (A₂) shows a triangular shaped fragment of broken Q surface or acetabular floor. b Moderate severe C fracture (B₁) 3D AP image and IL view (B₂) show a moderate severe injury by the extension of the primary vertical fracture line. c Most severe C fracture (C₁) 3D AP image and IL view (C₂) show severe impaction by the aggressive extension of primary and secondary fracture lines breaking through columns

Fig. 5

Interior lateral views showing striking characters of various impaction of C fractures in ascending order of severity

Fig. 6

Most severe pure superior C fracture, 3D AP view (A₁ and A₂) show complete vertical fracture line breaking along anterior part of ilium through acetabular roof; the anterior femoral head is exposed with intact Q surface. 3D AP view (B₁) shows separated fragment of anterior ilium with exposed right femoral head. The IL view (B₂) shows transverse fracture line dividing the Q surface