A torn meniscus is diagnosed through a combination of a physical exam and imaging, most commonly an MRI. Your doctor will start by examining your knee in the office using specific hands-on tests, then order imaging if a tear is suspected. The process typically moves from X-rays (to rule out bone problems) to an MRI that can show the meniscus in detail.
What Happens During the Physical Exam
Your doctor will begin by asking how you hurt your knee, what symptoms you’re experiencing, and whether you’ve noticed catching, locking, or swelling. They’ll check for instability, tenderness along the joint line, and any limits on your range of motion. This conversation and basic assessment narrows the possibilities before any specific testing begins.
Several hands-on maneuvers help identify a meniscus tear. The most common is the McMurray test: you lie on your back while the doctor bends your knee to 90 degrees, rotates your lower leg, and then straightens it again. They’re feeling and listening for a click or catch inside the joint and asking whether you feel pain during the movement. It requires no special equipment and takes just a minute or two.
The McMurray test is useful as a first step, but it only identifies a meniscal tear about 61% of the time. Another test, the Thessaly test, involves standing on the affected leg with the knee slightly bent and rotating your body. Some studies have found it to be more accurate, with sensitivity around 90% and specificity around 96%, though other research has produced less impressive numbers. No single physical exam maneuver is reliable enough on its own to confirm or rule out a tear, which is why imaging usually follows.
Why X-Rays Come First
X-rays cannot show a meniscus tear because the meniscus is soft tissue, not bone. But they’re almost always the first imaging step. Their job is to rule out fractures, loose bone fragments, and osteoarthritis, all of which can cause similar symptoms. According to the American College of Radiology, knee X-rays are the appropriate initial imaging study for knee pain in patients five years and older.
If X-rays look normal or show only fluid in the joint (an effusion), that’s when an MRI becomes the next step. About 20% of patients with chronic knee pain get an MRI without having had recent X-rays first, which guidelines consider premature.
How MRI Confirms the Tear
MRI is the gold standard for visualizing a torn meniscus. It creates detailed images of soft tissue inside the knee, showing both the location and severity of a tear. For tears on the inner (medial) meniscus, MRI has a sensitivity of about 91% and specificity of 94%, meaning it correctly identifies the vast majority of tears and rarely flags a healthy meniscus as torn. For the outer (lateral) meniscus, accuracy drops somewhat, with sensitivity around 73% and specificity around 91%.
The MRI itself is painless. You’ll lie still inside a tube-shaped machine for 30 to 45 minutes while it captures images of your knee. No contrast dye is needed for a standard meniscus evaluation. Your doctor will use the results to determine the tear type (radial, horizontal, bucket-handle, and so on), its size, and whether it’s in a region with blood supply, since that affects whether the tear can heal.
Ultrasound as an Alternative
Point-of-care ultrasound is sometimes used in emergency or urgent care settings because it’s fast, inexpensive, and available immediately. For medial meniscus tears, ultrasound has shown sensitivity around 89% and specificity around 90% in some studies, with an overall accuracy of about 89% compared to MRI’s 93%. It can also be performed dynamically, meaning the doctor can move your knee during the scan to watch how the joint behaves in real time.
The main drawback is that ultrasound is highly operator-dependent. Its accuracy varies significantly based on the skill of the person performing it, and it hasn’t been studied as thoroughly for lateral meniscus tears or in older patients. It works best as a quick screening tool, not a replacement for MRI when a definitive diagnosis is needed.
Conditions That Mimic a Meniscus Tear
Part of the diagnostic process is ruling out other problems that cause similar knee pain. Pain along the inner side of the knee could come from a medial collateral ligament sprain, pes anserine bursitis (inflammation of a fluid-filled sac below the joint), or medial plica syndrome. Lateral knee pain might stem from an iliotibial band issue or a ligament sprain on the outer side. A Baker’s cyst behind the knee, osteoarthritis, or even gout can also produce overlapping symptoms. Your doctor’s physical exam and imaging together help distinguish a meniscus tear from these other conditions.
Why Age Matters in Diagnosis
One of the trickiest aspects of diagnosing a meniscus tear is that many tears cause no symptoms at all. About 32% of people aged 50 to 59 with no knee pain have a meniscal tear visible on MRI. That number climbs to 56% in people aged 60 to 90. In people over 70, the majority have an asymptomatic tear. This means that finding a tear on MRI doesn’t automatically mean it’s the source of your pain, especially as you get older.
Because of this, doctors weigh MRI findings against your symptoms, exam results, and age. A torn meniscus on imaging in a 25-year-old athlete who felt a pop during a pivot is almost certainly the problem. The same finding in a 65-year-old with gradual-onset knee aching may be an incidental discovery unrelated to what’s actually causing the pain. A good diagnosis considers the full picture, not just the scan.
What Happens After Diagnosis
Once a tear is confirmed and matched to your symptoms, your doctor will classify it by type, location, and size. These details determine whether the tear is likely to respond to rest and physical therapy or whether surgical repair is worth considering. Tears in the outer third of the meniscus, where blood supply is better, have a higher chance of healing. Tears in the inner two-thirds, where blood flow is minimal, often don’t heal on their own. Your treatment path depends on this information along with your age, activity level, and how much the tear is affecting your daily life.