DOS 2016

198

· DOS Abstracts

Assessment of pelvic tilt and acetabular

parameters in patients with retroversion of the

acetabulum using conventional X-rays and the EOS

2D Imaging System.

Anne Soon Bensen, Carsten Jensen, Bo Mussmann, Trine Torfing, Ole Ovesen,

Søren Overgaard

Department of Orthopedic Surgery, The Hospital of South-West Jutland; Department

of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of

Radiology, Odense University Hospital; Department of Radiology, Odense University

Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University

Hospital

Background:

Retroversion of the acetabulum is a subgroup within hip dysplasia (HD).

For diagnosing several X-rays of the pelvis are required. The EOS 2D Imaging System

may be an option. To our knowledge no studies have compared EOS-images of the pelvis

with conventional radiographs in a population with retroversion of the acetabulum.

Purpose / Aim of Study:

1) To compare conventional AP-radiographs and EOS of the

pelvis with regard to pelvic tilt and acetabular parameters describing acetabular retrover-

sion. 2) To evaluate changes in these parameters when changing from standing to sitting

position using EOS.

Materials and Methods:

A cohort of 34 subjects with retroversion of the acetabulum

on standing AP- radiographs, were included. Two EOS- images of the pelvis in stand-

ing and sitting position were obtained. Radiographs and EOS-images were all assessed

for radiographic signs of retroverted acetabulum (cross-over-sign, posterior-wall- sign,

ischial-spine-sign), center-edge-angle < 25°, acetabular-index > 10°, pelvic tilt, rota-

tion and sagittal pelvic parameters.

Findings / Results:

1) Standing AP-radiographs versus EOS- images showed a sig-

nificant difference in AP-pelvic tilt due to magnification (p<0001). No difference in

any of the other parameters between the two modalities were found. 2) EOS-images

showed that the pelvis tilted backwards when subjects were repositioned from standing

to sitting. The presence of radiographic signs of retroversion was significantly reduced

(p<0.0001) but no significant difference in number of patients with center-edge-angle

< 25° or acetabular- index > 10° between the two positions was seen.

Conclusions:

Standard X-rays and EOS showed no significant difference. Using EOS pel-

vic tilt changed significantly from standing to sitting. In perspective: EOS may have the

potential to be used to assess acetabular orientation and HD.

No conflicts of interest reported

149.