Axial magnetic resonance (MR) imaging of the patellofemoral compartment was performed in 75 patients with arthroscopic correlation.
Proton density and T2(2500/20/80) weighted images were obtained in all patients.
Chondromalacia in stages I and II could not be reliably identified with MR imaging. For the evaluation of stage III and IV
chondromalacia, the accuracy of MR was 89%. Focal or diffuse areas of increased or decreased signal alterations of the hyaline cartilage without a contour
deformity or cartilaginous thinning do not correlate reliably with arthroscopic staging of
chondromalacia. A normal signal intensity is no assurance that softening of the cartilage is not present. The most reliable indicators of
chondromalacia are focal contour irregularities of the hyaline cartilage and/or thinning of the hyaline cartilage associated with high signal intensity changes within frank defects or contour irregularities with T2-weighted images. The poor MR-arthroscopic correlation in earlier stages of
chondromalacia may be due in part to the subjective basis of the arthroscopic diagnosis. In conclusion, stage I and II
chondromalacia of the patellofemoral compartment cannot be reliably evaluated with MR imaging. Stage III and IV
chondromalacia is reliably evaluated with MR using the combination of
proton density and T2-weighted images.