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S. Lippacher, H. Reichel, M. Nelitz
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The additional regression analysis showed a
conspicuous effect of the method on D.
Dejour’s classification as well as two-grade
classification which reinforces the poor
agreement between radiographs and MRI. Less
severe dysplasias were documented when
analyzing lateral radiographs than analyzing
MRI-scans.
Besides the D. Dejour classification, different
measurements to assess the morphology of the
femoral trochlea are described in the literature
[3, 4, 5, 12, 18, 22, 24].
Although inter- and intra- observer agreements
of the classification of Pfirrmann, Carrillon and
Biedert [3, 4, 5, 18] seem to be higher, they are
not as workable as D. Dejour’s classification in
clinical practice in our opinion.
So the authors still think that D. Dejour’s
classification is a good instrument for inter
preting trochlear dysplasia. Although it is easy
to apply using D. Dejour’s classification several
issues have to be considered:
1.
The four-grade analysis shows fair intra- and
interobserver agreement while the two-grade
analysis show good to excellent agreement.
2.
The best overall agreement was found for the
two-grade analysis on MRI-scans.
3.
The lateral radiograph tends to underestimate
the severity of trochlear dysplasia compared
to axial MR imaging.
In summary D. Dejour’s classification is valid
for typing trochlear dysplasia and is particularly
useful in separating low-grade from high-grade
cases. For clinical purposes the discrimination
between low-grade and high-grade dysplasia is
an important distinction because prognosis and
treatment mainly depend on the severity of
trochlear dysplasia.
Abstract
Trochlear dysplasia is known to be an important
cause for patellofemoral instability. Dejour’s
radiographic andMRI classifications are widely
used in clinical practice and in orthopaedic
literature to assess the severity of trochlear
dysplasia.
From fifty patients, fifty lateral radiographs as
well as fifty MRI-scans were read twice
independently within four weeks by four
surgeons (two senior and two junior examiners).
Analysis was made four-graded according to
D. Dejour’s four grades of radiological criteria
of trochlear dysplasia as well as two-graded
differentiating between low-grade (type A) and
high-grade trochlear dysplasia (type B-D).
The four-grade analysis shows fair intra- and
interobserver agreement while the two-grade
analysis shows good to excellent agreement.
The best overall agreement was found for the
two-grade analysis on MRI-scans. The lateral
radiograph tends to underestimate the severity
of trochlear dysplasia compared to axial MR
imaging.
D. Dejour’s classification is valid for typing
trochlear dysplasia and is particularly useful in
separating low-grade from high-grade dysplasia.