Meniscus Tear
The meniscus is a critical component of knee anatomy. In each knee there are two menisci, crescent-shaped pieces of fibrocartilage that sit between the thigh bone (femur) and the shin bone (tibia). These structures act as shock absorbers, distribute weight across the knee joint, enhance stability, and help lubricate and nourish the cartilage. Without healthy menisci, the knee experiences uneven pressure, leading to early wear and degeneration. The design of the meniscus allows it to cushion forces from everyday activities like walking and stair climbing, as well as from more strenuous actions such as running or jumping. Because the meniscus bears significant mechanical load, it is vulnerable to injury.
A meniscus tear refers to a split in the meniscal cartilage. Tears vary widely in pattern and severity. Some are small and located on the outer edge of the meniscus, where blood supply is relatively rich. Others are larger, more complex, or occur deeper within the central portion of the meniscus, where blood supply is limited. The pattern of the tear, such as radial, horizontal, flap, or bucket-handle, can influence symptoms and the options for treatment. The meniscus does not heal well on its own, especially in areas with poor circulation. When the cartilage is torn, the knee’s ability to absorb shock and stabilize properly can be compromised, leading to pain and dysfunction.
Symptoms can be subtle or quite pronounced. Many people notice pain along the inner or outer aspect of the knee that worsens with activity. Swelling often develops within the first 24 to 48 hours after injury, although in some cases swelling may be minimal.
A sensation of catching, locking, or a feeling that the knee is “giving way” can occur when a torn fragment interferes with normal joint motion. Some individuals experience stiffness and difficulty fully bending or straightening the knee. Tenderness along the joint line is common, and pain may intensify when squatting or twisting the knee. In chronic tears or degenerative cases, symptoms may come and go, making it difficult to pinpoint an exact cause.
Causes of meniscus tears can be broadly categorized as traumatic or degenerative. In young, active individuals, a tear typically results from a sudden twisting motion while the foot is planted, such as during sports that involve rapid direction changes. Forceful contact or deep squatting under load may also lead to a tear. Up to 66% of Anterior Cruciate Ligament (ACL) tears are associated with meniscus tears.
In contrast, older adults are more likely to experience degenerative tears. With age, the meniscal tissue becomes less resilient and more susceptible to fraying and tearing even during ordinary activities like stepping off a curb or rising from a chair. Individuals with preexisting knee arthritis are at particularly high risk, as the worn joint surfaces place added stress on the menisci.
Diagnosis begins with a comprehensive medical history and physical examination. A clinician will inquire about the mechanism of injury, the onset and pattern of symptoms, and any factors that exacerbate or relieve discomfort. During the physical exam, specific tests are performed to assess for meniscal injury, including maneuvers that place stress on the cartilage to elicit pain, clicking, or restricted motion. The examiner will also evaluate knee stability, ligament integrity, and range of motion to rule out other potential causes of knee pain.
Imaging studies play an essential role in confirming the diagnosis. Plain X-rays do not show meniscal cartilage, but they are useful to assess overall joint health, alignment, and the presence of degenerative changes or arthritis.
Magnetic resonance imaging (MRI) is the gold standard for visualizing the soft tissues of the knee, including the menisci, ligaments, and cartilage. An MRI may identify associated injuries such as ligament tears or cartilage defects that could influence treatment.
Living with a meniscus tear can be challenging, but accurate diagnosis, individualized treatment planning, and appropriate rehabilitation allow many individuals to return to meaningful activity. Early recognition of symptoms and prompt evaluation can prevent further damage and optimize outcomes.
