Diagnostic processes for meniscal tears aim to determine first and foremost whether a tear is present, or whether the knee symptoms are caused by something else. From that point, diagnostic tests will attempt to determine which meniscus is torn, how severely it is damaged, and what treatment is recommended.
Diagnosing meniscal tears of any size, location or severity will typically center on three primary methods:
A doctor will first assess if a tear has occurred by asking questions about the onset. He or she may inquire as to whether the pain was immediate, whether or not the pain was accompanied by a popping sounds and whether or not the knee over rotated.
A doctor will usually consider and discuss the individual’s medical history before making recommendations for treatment. For example, patients who have suffered several meniscal tears in the past or have degenerated menisci may be more qualified candidates for a meniscectomy than those who have sustained only their first tear.
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After determining the medical history of the patient, the physical exam will typically include determining whether leg locking is present and indicative of a torn piece of cartilage locked in the knee joint, and whether the tear is of the lateral or medial meniscus.
A physician may attempt to gauge a patient’s range of motion by moving the leg in different directions.
The McMurray Test is commonly used as follows:
- A physician will flex the patients leg to or beyond 90 degrees of extension, as though it were straightening.
- Once the leg is straightened, a physician will hold the calf and turn the leg in both directions, so that the tibia rotates on top of the femur both internally and externally.
- Internal rotation tests for tears of the lateral meniscus, while external tests the medial meniscus. As this is performed, the doctor lightly touches, or palpates, the knee.
- In the event of an injury being present, these palpations will produce a thud or click.1
The Apley’s Compression test is commonly used as follows:
- The patient lies on his or her stomach, bending the knee at an even 90 degree angle.
- Downward force will be applied to the foot by the physician while the foot is rotated to the outside.
- If pain presents itself in the inner section of the knee joint, a medial meniscal tear may be present.2
If surgery is considered, a magnetic resonance imaging (MRI) scan for the knee may be ordered. MRI scans allow for deeper viewing of the soft tissues in the knee joint, which can be integral in determining the location and severity of the tear. It will also indicate how much excess fluid is in the knee and whether or not any torn piece of the meniscus has lodged within the joint itself.
Diagnosing a meniscal tear may require the use of several methods. For example, if the knee is swollen or retaining fluid, an MRI will be necessary as the physician will be able to garner less from physical examination alone.
A diagnosis may include the type of tear. Typical meniscus tears may be described as:
- Flap tear. In a flap tear, the tear occurs on the side of the meniscus, splitting the inner tissue away from the edge and causing a flap.
- Degenerative tear. With a degenerative tear, damage to the meniscus over time causes a progressively increasing tear near the outside of the meniscus.
- Bucket handle tear. A bucket handle runs between the outer edge of the meniscus and the interior tissue. As the edge of the meniscus is separated from the rest of the cartilage, if the torn piece of cartilage were lifted up the shape of a bucket handle is formed.
- Radial tear. In a radial tear, a tear occurs on one edge of the meniscus and moves into the tissue, perpendicular to the edge.
Understanding the type and severity of mensicus tear will help guide treatment decisions.