Normal articular cartilage consists of three separate zones, variably visualized as distinct layers on MRI depending on spatial resolution. At lower resolutions, truncation artifact, which occurs at interfaces of high tissue contrast, may mimic this trilaminar appearance. Protons within highly organized collagen fibers at the articular surface and superficial zone exhibit accelerated T2 decay, resulting in a decreased SI on T2WI. Fibers within the deeper transitional zone are less organized exhibiting hyperintensity on T2WI. The deep radial zone collagen fibers are also well-organized, correlating again with a decreased SI on T2WI. On T1WI there is little intrinsic tissue contrast between synovial fluid and articular cartilage, therefore FSE T2WI or PDWI, which give an arthrographic effect (partially aided by magnetization transfer), are preferred for visualization of articular cartilage defects. Choice of longer echo times, however, may impair delineation of cartilage from subchondral bone. Other disadvantages with FSE T2WI include the image blur and chemical shift artifacts that may be corrected, respectively, by reducing echo-train length and obtaining FS images. The thinness of articular cartilage renders 3D GRE T1WI a reasonable sequence by which to obtain high spatial resolution scans without interslice gaps. The trilaminar structure of articular cartilage is reliably demonstrated with this technique, although at the cost of longer acquisition times, greater sensitivity to susceptibility artifact, and poorer visualization of nearby other soft tissue structures. Postoperative evaluation is optimally performed with FSE imaging. Low-field MRI has been shown inferior for the detection of cartilaginous lesions due to problems in implementing the above sequences. Direct MR arthrography confirms an unstable fracture when contrast extends underneath the fragment, although the invasiveness of the technique, especially in the serial MRI evaluations that are often performed, impairs its utility.