Meniscal tear

What it means

Inside the knee, between the rounded end of the thigh bone and the flat top of the shin bone, sit two rubbery C-shaped pads of cartilage — the menisci. They cushion the joint, spread load evenly, and help keep the knee stable when it twists. A tear is a split or crack in one of these pads. It can be a small surface fissure or a longer crack that runs through the pad's thickness, and it can sit on the inner (medial) or outer (lateral) side of the knee.

Why it appears on a CT or MRI report

Most tears are diagnosed on MRI. Reports describe which meniscus is torn (medial or lateral), which part (anterior horn, body, or posterior horn), the shape of the tear (horizontal, radial, longitudinal, complex, or bucket-handle), and whether a fragment has flipped or displaced. The radiologist will also note the surrounding tissue: any joint fluid, arthritis changes, ligament injuries (especially the ACL), or bone bruising that might have happened at the same time.

What it usually means

There are two broad patterns. Acute tears happen during a clear event — a twisting injury during sport, a deep squat, or a fall — and often cause a pop, pain, swelling, and sometimes a feeling of the knee catching or locking. Degenerative tears develop slowly as the cartilage wears with age and are common after 40; large studies have found meniscal tears on the MRIs of many adults who have no knee pain at all. So a tear seen on a scan is not automatically a tear that needs surgery. Many degenerative tears settle with physical therapy, anti-inflammatories, and time. Acute tears in younger active people, especially bucket-handle tears that lock the knee, are more likely to be considered for arthroscopic repair or trim. As with most musculoskeletal findings, what the picture shows has to match what the knee actually feels like.

When to follow up

Talk to your doctor if you have knee pain after a twisting injury, persistent swelling, a feeling that the knee catches, clicks, or locks, or instability when walking or going down stairs. They'll match the imaging against the exam to decide between physical therapy, activity changes, injections, or referral for an arthroscopic opinion. Sudden inability to straighten the knee (a locked knee), severe pain after a major injury, or numbness and weakness in the leg deserves prompt care.

A plain-language way to picture it

Imagine two smooth stones with a thick C-shaped rubber gasket between them, sitting on each side. Now imagine twisting the top stone hard while the bottom one stays put — the rubber gets pinched and a crack opens along one side. The stones still rest on it, but every time they move, the crack catches a little. A meniscal tear is that crack: small ones rub quietly, larger ones can flap into the moving parts.