The meniscus refers to two C-shaped pieces of cartilage within each knee joint, serving as cushions between the shinbone (tibia) and thighbone (femur). These structures absorb shock, distribute weight, stabilize the joint, and reduce friction during movement. A tear in this cartilage represents a common knee injury, often resulting from twisting motions or direct impact.
Common Signs of a Meniscus Tear
A torn meniscus often causes a range of symptoms. Pain in the knee joint is a primary indicator, frequently worsening with activities like twisting, squatting, or going up and down stairs. Swelling around the knee is also common, though it may develop gradually over several hours or days following the injury. This swelling can lead to stiffness or tightness, limiting the ability to fully bend or straighten the leg.
A popping sensation might be felt at the time of injury, and some people report clicking, catching, or locking of the knee during movement. This locking occurs when torn cartilage interferes with joint motion. Additionally, the knee may feel unstable or give way, leading to a feeling of unreliability when bearing weight. These signs collectively suggest the need for medical evaluation.
Clinical Examination by a Doctor
A thorough clinical examination is the initial step a healthcare professional takes to assess for a meniscus tear. During this examination, the doctor will observe the knee for visible swelling or deformity and gently touch the joint line to check for tenderness, which often indicates a tear. The range of motion of the knee will also be evaluated, noting any limitations in bending or straightening the leg.
Specific physical tests, known as provocative maneuvers, are performed to help confirm a meniscus tear by attempting to reproduce symptoms. The McMurray test is a frequently used assessment where the doctor bends the patient’s knee, then straightens and rotates it. Pain, a clicking sound, or a clunking sensation during this maneuver suggests a tear in either the medial or lateral meniscus.
The Apley compression test involves the patient lying face down while the doctor applies downward pressure to the heel and rotates the lower leg. Pain elicited during this compression and rotation can point to a meniscus injury. Another relevant test is the Thessaly test, performed with the patient standing on the affected leg, slightly bending the knee, and then rotating the body. Reproducing knee pain or a locking sensation during these movements further supports the possibility of a torn meniscus. These hands-on tests help pinpoint the location and potential severity of the injury.
Imaging Techniques for Diagnosis
While physical examination provides valuable insights, imaging techniques are often used to confirm a meniscus tear and rule out other knee conditions. Magnetic Resonance Imaging (MRI) is the most effective and common imaging modality for diagnosing meniscus tears. An MRI uses strong magnetic fields and radio waves to create detailed images of soft tissues, including the menisci, cartilage, tendons, and ligaments within the knee joint. This allows for clear visualization of the tear’s location, type, and extent.
X-rays are typically performed first in a diagnostic workup, although they do not directly show meniscus tears. X-rays are useful for ruling out other potential causes of knee pain, such as bone fractures or signs of arthritis. By eliminating bony abnormalities, the focus can then shift more specifically to soft tissue injuries like a torn meniscus, for which MRI provides superior detail.
Diagnostic Arthroscopy
When other diagnostic methods, such as physical examination and imaging, do not provide a definitive diagnosis, or if symptoms persist, diagnostic arthroscopy may be considered. This procedure is a minimally invasive surgical technique that offers a direct, internal view of the knee joint. During an arthroscopy, a small incision is made in the knee, through which a thin tube with a camera and light source, called an arthroscope, is inserted.
The camera transmits real-time images to a monitor, allowing the surgeon to thoroughly examine the menisci, articular cartilage, ligaments, and other structures within the knee. This direct visualization provides exceptional diagnostic precision, enabling the identification of tears that might be difficult to detect with other methods. If a meniscus tear is found during diagnostic arthroscopy, the surgeon can often proceed immediately with repair or removal of the damaged tissue, depending on the tear’s characteristics.