The aim of the study was to apply 3D measurements for fracture displacement in minimally to moderately displaced acetabular fractures treated nonoperatively, and to evaluate whether this measurement can be used to estimate the likelihood of conversion to total hip arthroplasty (THA) at follow-up. A multicentre, cross-sectional study was performed on 144 patients who were treated nonoperatively for an acetabular fracture in four level 1 trauma centres between January 2000 and December 2020. For each patient, fracture displacement was measured on CT-based 3D models. The 3D gap area represents fracture displacement (mm2) between all fracture fragments. A receiver operating characteristic curve was generated to determine a 3D gap area threshold representing the optimal sensitivity and specificity to predict conversion to THA. Native hip survival was reported using Kaplan-Meier curves. Predictors of conversion to THA were determined using Cox regression analysis.Aims
Methods
We describe the routine imaging practices of
Level 1 trauma centres for patients with severe pelvic ring fractures, and
the interobserver reliability of the classification systems of these
fractures using plain radiographs and three-dimensional (3D) CT
reconstructions. Clinical and imaging data for 187 adult patients
(139 men and 48 women, mean age 43 years (15 to 101)) with a severe
pelvic ring fracture managed at two Level 1 trauma centres between July
2007 and June 2010 were extracted. Three experienced orthopaedic
surgeons classified the plain radiographs and 3D CT reconstruction
images of 100 patients using the Tile/AO and Young–Burgess systems.
Reliability was compared using kappa statistics. A total of
115 patients (62%) had plain radiographs as well as two-dimensional
(2D) CT and 3D CT reconstructions, 52 patients (28%) had plain films
only, 12 (6.4%) had 2D and 3D CT reconstructions images only, and
eight patients (4.3%) had no available images. The plain radiograph
was limited to an anteroposterior pelvic view. Patients without
imaging, or only plain films, were more severely injured. A total
of 72 patients (39%) were imaged with a pelvic binder Interobserver reliability for the Tile/AO (Kappa 0.10 to 0.17)
and Young–Burgess (Kappa 0.09 to 0.21) was low, and insufficient
for clinical and research purposes. Severe pelvic ring fractures are difficult to classify due to
their complexity, the increasing use of early treatment such as
with pelvic binders, and the absence of imaging altogether in important
patient sub-groups, such as those who die early of their injuries. Cite this article:
We evaluated the impact of stereo-visualisation of three-dimensional volume-rendering CT datasets on the inter- and intraobserver reliability assessed by kappa values on the AO/OTA and Neer classifications in the assessment of proximal humeral fractures. Four independent observers classified 40 fractures according to the AO/OTA and Neer classifications using plain radiographs, two-dimensional CT scans and with stereo-visualised three-dimensional volume-rendering reconstructions. Both classification systems showed moderate interobserver reliability with plain radiographs and two-dimensional CT scans. Three-dimensional volume-rendered CT scans improved the interobserver reliability of both systems to good. Intraobserver reliability was moderate for both classifications when assessed by plain radiographs. Stereo visualisation of three-dimensional volume rendering improved intraobserver reliability to good for the AO/OTA method and to excellent for the Neer classification. These data support our opinion that stereo visualisation of three-dimensional volume-rendering datasets is of value when analysing and classifying complex fractures of the proximal humerus.
