Indications for MRA include evaluation of osteochondral defects for stability and evaluation of postoperative menisci for retear.Matrix collagen has a leaf-like structure with proteoglycans projecting from a central hyaluronic acid backbone.Tags: Research Paper On Abortion Pro LifeEssay Reflections English ClassSociological Imagination Autobiography EssayFukushima Nuclear Power Plant Disaster Case StudyArgumentative Essay AudiencePuttermesser Papers Wiki
Grade 4 lesions extend into the subchondral bone and may require bone grafting if bony cavitation is extensive.
Subchondral marrow edema is more likely to be associated with higher-grade lesions and, in the setting of acute trauma, indicates that the lesion may be full thickness.
The orientation of the cartilage relative to the orientation of the static magnetic field (B) also affects the thickness, signal intensity, and distinctness of these layers.
Therefore, since much of the cartilage surfaces of the knee are curved (eg, the femoral condyles), appearance of the articular cartilage varies.
Bredella et al reported that the sensitivity, specificity, and accuracy of combined axial and coronal FSE T2-weighted sequences with fat suppression compared with the gold standard of arthroscopy were 94%, 99%, and 98%, respectively.
In their study, 64% of the lesions were given the same grade as that shown during arthroscopy.
This finding is nonspecific, as it is often seen in asymptomatic patients; concurrent underlying marrow signal abnormality increases its specificity.
Cartilage defects appear as synovial fluid-filled, T2 hyperintense gaps that disrupt the articular surface.
The uniformity of the collagen fiber orientation at the articular and the bony surfaces helps to elucidate the reason magic angle phenomenon affects cartilage (Figure 2), and the curvature of the collagen fibers also helps to explain the curved appearance of many cartilage lesions.
Chondromalacia, or cartilage softening, without surface cartilage defect is the earliest stage of cartilage injury and may appear on MRI as focal areas of increased signal intensity on T2-weighted images (Figure 3).