Background: Complex fractures of the distal part of the humerus can
be difficult to characterize on plain radiographs and two-dimensional computed
tomography scans. We tested the hypothesis that three-dimensional
reconstructions of computed tomography scans improve the reliability and
accuracy of fracture characterization, classification, and treatment
decisions.
Methods: Five independent observers evaluated thirty consecutive
intra-articular fractures of the distal part of the humerus for the presence
of five fracture characteristics: a fracture line in the coronal plane;
articular comminution; metaphyseal comminution; the presence of separate,
entirely articular fragments; and impaction of the articular surface.
Fractures were also classified according to the AO/ASIF Comprehensive
Classification of Fractures and the classification system of Mehne and Matta.
Two rounds of evaluation were performed and then compared. Initially, a
combination of plain radiographs and two-dimensional computed tomography scans
(2D) were evaluated, and then, two weeks later, a combination of radiographs,
two-dimensional computed tomography scans, and three-dimensional
reconstructions of computed tomography scans (3D) were assessed.
Results: Three-dimensional computed tomography improved both the
intraobserver and the interobserver reliability of the AO classification
system and the Mehne and Matta classification system. Three-dimensional
computed tomography reconstructions also improved the intraobserver agreement
for all fracture characteristics, from moderate (average kappa
[?2D] = 0.554) to substantial agreement (?3D
= 0.793). The addition of three-dimensional images had limited influence on
the interobserver reliability and diagnostic characteristics (sensitivity,
specificity, and accuracy) for the recognition of specific fracture
characteristics. Three-dimensional computed tomography images improved
intraobserver agreement (?2D = 0.62 compared with
?3D = 0.75) but not interobserver agreement
(?2D = 0.24 compared with ?3D = 0.28) for
treatment decisions.
Conclusions: Three-dimensional reconstructions improve the
reliability, but not the accuracy, of fracture classification and
characterization. The influence of three-dimensional computed tomography was
much more notable for intraobserver comparisons than for interobserver
comparisons, suggesting that different observers see different things in the
scans—most likely a reflection of the training, knowledge, and
experience of the observer with regard to these relatively uncommon and
complex injuries.
Clinical Relevance: In our opinion, three-dimensional computed
tomography is helpful for preoperative planning of the operative treatment of
fractures of the distal part of the humerus.