Heino Brechter J, Powers CM, Terk MR, Ward SR, Lee TQ.
To describe a method for quantifying patellofemoral joint contact area using
magnetic resonance imaging (MRI), we used a repeated measures design using
cadaver specimens. The use of contact area obtained from cadaveric specimens for
biomechanical modeling does not permit investigators to assess the inter-subject
variability in contact area as a result of patellofemoral pathology or
malalignment. Therefore, a method for measuring patellofemoral joint contact area
in-vivo is necessary. Six fresh frozen unmatched human cadaver knees were thawed
at room temperature and minimally dissected to permit insertion of a pressure
sensitive film packet into the suprapatellar pouch. A custom loading apparatus
was designed to apply a compressive load to the patellofemoral joint at 30
degrees of flexion. Simultaneous measurement of contact area was made using both
the pressure sensitive film technique and MRI. The intraclass correlation
coefficient (ICC) and coefficient of variation were used to compare the agreement
between the two methods and to assess the repeatability of the MRI method. Good
agreement was found between the MRI and pressure sensitive film techniques (ICC
0.91; CV 13%). The MRI technique also was found to be highly reproducible (ICC
0.98; CV 2.3%). MRI assessment of patellofemoral joint contact area was found to
be comparable to the established pressure sensitive film technique. These results
suggest that this method may be a valuable tool in quantifying patellofemoral
joint contact area in-vivo. Quantification of the patellofemoral joint stress has
been dependent on patellofemoral joint contact area obtained from cadaver
specimens, thereby negating the potential influence of subject specific
variability. Developing a non-invasive technique to evaluate contact area will
assist researchers and/or clinicians in obtaining patient-specific contact area
data to be used in biomechanical analyses and clinical decision making.
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