T. Hufner et al., Classification of acetabular fractures. A systematic analysis of the relevance of computed tomography, UNFALLCHIRU, 102(2), 1999, pp. 124-131
The classification of acetabular fractures and especially the diagnosis of
additional lesions can be misleading, when the personal experience is limit
ed and the decisions are based only on conventional radiographs. The introd
uction of Spiral-CT with multiplanar reformations and 3-D views has improve
d the quality of visualization. Due to their higher costs, the need of thes
e additional diagnostic tools is frequently questioned. This paper discusse
s the relevance of plain radiographs, 2-D-CTs, 3-D-CTs and Femursubtraction
-CTs (FsCT) for the classification of aceta bu lar fractures, based on a co
ntrolled study. Methods: Thirty physicians with different levels of experie
nce in acetabular surgery were divided in three groups of 10 each: group I
comprised residents without operative experience in acetabular surgery, gro
up II was physicians with 3-10 years of operative experience, and group III
was experts in acetabular surgery. A total of 10 complete radiographic cas
es of high quality providing all levels of preoperative diagnostics (plain
radiographs, 2-D-CT, CT with multiplanar reformation, 3-D-CT, Fs-CT) of dif
ferent acetabular fracture types were prepared. The task for each candidate
was to classify the fracture according to Letournel and to identify all ad
ditional injuries within the hip joint (e. g. marginal impaction, head frac
tures, etc.). The different diagnostic "levels" could be ordered stepwise a
ccording to personal need and no time limit was given. The case was finishe
d when the candidate presented his final diagnosis. The use of the differen
t radiographs, the preliminary diagnosis, the changes in diagnosis, and the
final decisions were recorded. These findings were correlated with the dif
ferent levels of experience and against a "consensus classification" which
was generated by thorough discussion, and the use of intraoperative informa
tion and postoperative radiographs not accessible to the candidates. Result
s: The "correct" fracture classification based on plain radiographs was: gr
oup I, 11%; group II, 32%; group ill, 61%. Based on 2-D-CT a "correct" diag
nosis was reached by 30% in group I, by 55% in group II, and by 76% in grou
p Iii. With consideration of the "transient forms" in acetabular fractures
based on Letournel and the 3-D-CT used mainly by group I, the rate of "corr
ect" classifications rose to 65% in group I, 64% in group II and 83% in gro
up III. The modifiers were diagnosed "correctly" in group I by 37%, in grou
p II by 56%, and in group III by 73%. The use of the 3-D-CT and especially
the Fs-CT by group I resulted in an improvement in the rate of correct clas
sifications to 61%, whereas in group II the Fs-Ct was used only exceptional
ly. The 2-D-CT was the basis for the diagnosis of the additional lesions in
acetabular fractures within all groups resulting in 73% complete diagnoses
in group III. This study showed the importance of CT for the exact analysi
s and classification of acetabular fractures. In particular, the secondary
reformations in CT and the 3-D-views dramatically improved the rate of "cor
rect" classifications in the group of surgeons with limited personal expere
nce in acetabular surgery. This allows the less experienced an acceptable l
evel of "correct" diagnoses, so that the treatment options can be weighed c
orrectly. Among the "experts" a rate of divergent classifcations of approxi
mately 20% was observed, especially in "transient" forms of acetabular frac
tures.