A medial meniscus tear is a common knee injury involving damage to the C-shaped cartilage pad on the inner side of your knee joint. This cartilage cushions the space between your thighbone and shinbone, and when it tears, it can cause pain, swelling, and mechanical problems like catching or locking. Meniscal tears affect roughly 66 out of every 100,000 people per year, with men injured two and a half to four times more often than women.
What the Medial Meniscus Does
Your knee has two menisci: the medial (inner) and lateral (outer). Both are made of tough, flexible cartilage that acts as a shock absorber and load distributor. The medial meniscus covers about 60% of the inner joint surface and carries roughly half the load on that side of the knee. Remove it, and the contact area between the bones drops by 50% to 70%, doubling the stress on the remaining cartilage. That’s why preserving as much meniscus as possible matters for long-term joint health.
The medial meniscus also plays a stabilizing role, particularly for people who have an injured anterior cruciate ligament (ACL). In an ACL-deficient knee, the posterior horn of the medial meniscus becomes the primary structure resisting forward sliding of the shinbone. Losing the medial meniscus in that situation increases abnormal forward-backward motion by up to 58%. This is why ACL injuries and medial meniscus tears often travel together and why surgeons take both into account when planning treatment.
Compared to the lateral meniscus, the medial meniscus is far less mobile. It shifts only about 2 mm during bending, while the lateral meniscus moves roughly 10 mm. That relative stiffness makes the medial side more vulnerable to getting trapped and torn during twisting movements.
Why Tears Happen at Different Ages
Medial meniscus tears fall into two broad categories: traumatic and degenerative. In younger people, tears typically result from a sudden twist or pivot, often during sports. A planted foot combined with a rotating knee is the classic mechanism. In a study of surgically treated patients, isolated medial tears had an average age of about 32 years, though overall meniscal tear prevalence peaked between ages 20 and 29.
As you get older, the cartilage dries out, stiffens, and loses some of its blood supply. By middle age, something as minor as squatting or stepping off a curb can tear a meniscus that has been gradually weakening for years. These degenerative tears become increasingly common after age 30. In surgical data, more than half of isolated medial meniscus injuries occurred in patients over 30, a rate significantly higher than for lateral tears in the same age group.
Types of Tears
Not all meniscus tears look or behave the same. The shape and direction of the tear determine both how it affects your knee and how well it can be treated.
- Horizontal tears run parallel to the bottom of the meniscus, splitting it into upper and lower halves. These are common in degenerative knees.
- Longitudinal tears run along the length of the meniscus, following its natural curve. When small, they may heal on their own if they’re in a well-supplied area.
- Radial tears cut inward from the free edge, slicing across the structural fibers that give the meniscus its strength. Because these fibers resist the outward push of body weight, a radial tear can significantly compromise load-bearing ability.
- Bucket-handle tears are a displaced version of a longitudinal tear, where the inner fragment flips into the center of the joint like the handle of a bucket. These are the tears most likely to cause true knee locking.
- Flap tears produce a loose piece of cartilage that can fold over and catch between the joint surfaces, causing intermittent catching or giving way.
Complex tears combine more than one pattern and are generally harder to repair.
Symptoms to Recognize
A torn medial meniscus doesn’t always announce itself dramatically. With smaller tears, pain and swelling may take 24 hours or more to develop. The most common symptoms include pain along the inner joint line (the crease on the inside of your knee), swelling or stiffness, and discomfort that worsens with twisting or deep bending.
Mechanical symptoms are what distinguish a meniscus tear from a simple strain. You may feel a pop at the time of injury, notice catching or clicking during movement, have difficulty fully straightening your knee, or experience the knee locking in place. Some people describe the knee suddenly giving way, as though it can’t be trusted to hold weight. Bucket-handle tears are particularly notorious for locking the knee in a bent position because the displaced fragment physically blocks full extension.
How Tears Are Diagnosed
Your doctor will start with a physical exam, pressing along the joint line and performing rotation tests to try to reproduce your symptoms. The McMurray test, which involves bending and rotating the knee while feeling for clicks, detects medial meniscus tears about 69% of the time. The Thessaly test, performed while standing and twisting on a slightly bent knee, catches about 64% of medial tears. Neither test is highly reliable on its own, so imaging usually follows when a tear is suspected.
MRI is the standard imaging tool. Radiologists grade meniscal changes on a three-level scale. Grade 1 shows a small dot of abnormal signal inside the meniscus, and Grade 2 shows a line of signal that stays contained within the cartilage. Neither of these reaches the surface, and neither represents a true tear. Grade 3 signal extends to at least one surface of the meniscus and indicates an actual tear. Only Grade 3 findings are clinically significant in terms of guiding treatment decisions.
Why Some Tears Heal and Others Don’t
The meniscus has an uneven blood supply that directly determines its ability to heal. The outer third, closest to the joint capsule, receives good blood flow. This is called the red-red zone. The middle third, or red-white zone, has partial blood supply. The inner third, the white-white zone, has essentially no blood vessels and relies on joint fluid for nutrition.
Tears in the red-red zone have the best chance of healing, whether on their own or after surgical repair. Tears in the white-white zone rarely heal because the tissue can’t mount an adequate repair response without blood supply. This vascular geography is one of the most important factors surgeons weigh when deciding between repair and removal.
Conservative Treatment
Not every meniscus tear needs surgery. Degenerative tears in particular often respond well to a structured rehabilitation program. The standard approach focuses on building quadriceps strength, improving flexibility, and restoring proprioception (your knee’s sense of where it is in space) over a period of eight to ten weeks. One study found that supervised quadriceps strengthening with stationary cycling three times a week for ten weeks improved knee function by 35% in patients with associated osteoarthritis.
In a trial comparing surgery plus exercise to exercise alone for degenerative medial meniscus tears, both groups showed similar improvement, reinforcing that conservative management is a reasonable first option. Functional improvement tends to continue for about six months, after which some patients experience a decline as underlying arthritis progresses. If a structured rehab program doesn’t relieve symptoms after several months, surgery becomes a more likely next step.
Surgical Options
When surgery is needed, the two main procedures are partial meniscectomy (trimming out the damaged portion) and meniscal repair (stitching the torn edges back together). The choice depends on the tear’s location, shape, and age, as well as the patient’s own age and activity level.
Meniscal repair is preferred when possible because it preserves tissue and protects the joint long-term. Repairs work best for tears in the blood-rich outer zone, particularly longitudinal and bucket-handle patterns. Bucket-handle tears were observed nearly six times more often in the repair group than the meniscectomy group in one comparative study. Younger patients tend to get better results from repair, with superior outcomes documented in patients under 45.
Meniscectomy is more common for complex tears (which made up about 51% of meniscectomy cases compared to 25% of repairs), tears in the avascular inner zone, and degenerative tears in older patients where the tissue quality is too poor for stitching. Surgeons generally avoid arthroscopic surgery for degenerative tears when advanced arthritis is already present, because outcomes tend to be poor and many of these patients end up needing joint replacement soon afterward. That said, age alone isn’t an automatic disqualifier for repair. Studies have shown similar five-year outcomes between repair and meniscectomy even in patients over 40.
Recovery After Surgery
Recovery timelines differ significantly between meniscectomy and repair. After a partial meniscectomy, you can typically bear weight almost immediately, and many people return to normal activities within a few weeks.
Meniscal repair requires more patience because the stitched tissue needs time to heal. How quickly you can put weight on the knee depends on the tear type. For longitudinal tears, partial weight-bearing can begin within the first one to two weeks, with full weight-bearing shortly after. Radial tears require four to six weeks before full weight-bearing. Root tears are the most restrictive, with no weight-bearing initially and full loading delayed until six to eight weeks after surgery.
Range of motion is also initially limited, typically to 0 to 90 degrees of bending for the first several weeks. Horizontal and root tears may take more than six weeks before full bending is allowed. For all repair types, conventional rehab protocols began weight-bearing at four to six weeks, though newer accelerated protocols allow some patients to reach full weight-bearing within four weeks under close supervision. Return to sport after a meniscal repair generally takes four to six months, depending on the tear pattern and the demands of the activity.