Ward SR, Shellock FG, Terk MR, Salsich GB, Powers CM.
To compare the level of agreement between quantitative and qualitative
methods in determining patellofemoral relationships, since controversy exists
regarding the use of quantitative vs. qualitative criteria to interpret images of
the patellofemoral joint (PFJ) obtained using kinematic magnetic resonance (MR)
MATERIALS AND METHODS:
One hundred twenty mid-patellar axial plane images
obtained using kinematic MR imaging from fifteen subjects were randomly selected
for analysis. MR images represented various knee flexion angles ranging from 0 to
60 degrees. Quantitative analysis (bisect offset and patellar tilt angle) was
performed by two examiners using a computer-assisted software program. Based on
data from previously published literature, MR images were characterized as
demonstrating normal, medial, or lateral patellar subluxation, and/or normal,
medial, or lateral tilt. Using similar categories, two different examiners
experienced in reading MR images of the PFJ then applied qualitative criteria to
the same images.
The average agreement between the quantitative and qualitative
assessments of horizontal patellar displacement and patellar tilt ranged from
poor to moderate (Kappa coefficient values of 0.27 and 0.45, respectively).
Quantitative and qualitative techniques demonstrated acceptable intra- and
These findings indicate that the use of quantitative criteria does
not compare well to qualitative criteria in the analysis of kinematic MR images
of the PFJ. One explanation for this discrepancy relates to the fundamental
difference between the techniques. That is, quantitative measurements are based
on the use of osseous landmarks, while the qualitative assessments tend to rely
on a description of patellofemoral relationships based on joint surfaces.
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