Torn Meniscus

How is a meniscus tear diagnosed?

The diagnosis of a knee injury begins with the history and physical examination. If there is an acute injury, the health-care professional will want to hear about the mechanism of that injury to help understand the stresses that were placed on the knee. With chronic knee complaints, the initial injury may not be remembered, but many patients who participate in athletic events or training can pinpoint the specific timing and details of the injury.

There is a true art to the physical examination of the knee. From inspecting (looking), palpating (feeling), and applying specific diagnostic maneuvers, the health-care professional can often make the diagnosis of a torn meniscus.

Physical examination often includes palpating the joint for warmth and areas of tenderness, assessing the stability of the ligaments, and testing the range of motion of the knee joint and the power of the quadriceps and hamstring muscles. There have been many tests described to assess the internal structures of the knee. The McMurray test, named after a British orthopedic surgeon, has been used for more than 100 years to make the clinical diagnosis of a torn meniscus. The health-care professional flexes the knee and rotates the tibia while feeling along the joint. The test is positive for a potential tear if a click is felt.

Magnetic resonance imaging (MRI) is the test of choice to confirm the diagnosis of torn meniscus. It is a noninvasive test that can visualize the inner structures of the knee, including the cartilage and ligaments, the surface of the bones, and the muscles and tendons that surround the knee joint. One additional benefit of the MRI before surgery is that by knowing the anatomy the surgeon can plan a potential operation and discuss alternatives with the patient.

Plain X-rays cannot be used to identify meniscal tears but may be helpful in looking for bony changes, including fractures, arthritis, and loose bony fragments within the joint. In older patients, X-rays may be taken of both knees while the patient is standing. This allows the joint spaces to be compared to assess the degree of cartilage wear. Cartilage takes up space within the joint and if the joint space is narrowed, it may be an indicator that there is less cartilage present, likely from degenerative disease.

Prior to the widespread use of MRI, knee arthroscopy was used to confirm the diagnosis of a torn meniscus. In arthroscopy, the orthopedic surgeon inserts a small scope into the knee and looks directly at the structures within the joint. The added benefit of arthroscopy is that the injury may be repaired at the same time using additional tools that are inserted into the joint. The disadvantage of arthroscopy is that it is a surgical procedure with all the potential risks that are associated with surgery.

Reviewed on 6/13/2014