1. In the large majority of injuries of the menisci, the diagnosis can be made on clinical grounds alone. Air arthrography is, however, useful as an aid to diagnosis, particularly in mixed lesions, such as tears of the anterior cruciate ligament associated with tears of the menisci, or simultaneous lesions of both menisci. The diagnosis of lesions of the medial meniscus is simpler than the diagnosis of lesions of the lateral meniscus.
2. Arthrography is of less value in the diagnosis of other lesions of the knee joint, but is occasionally useful.
3. Arthrography affords interesting information regarding the movements of the menisci during flexion and extension of the knee. These movements can be studied both with roentgenograms and by fluoroscope. When the knee is flexed, the medial meniscus tends to be drawn backward out of the joint, and for this reason is not trapped.
4. Although the injection of air into a joint may produce a transient effusion, this is in no way harmful. Arthrography is a safe and simple procedure, when done with full aseptic precautions.