Pain on the inside of your knee, known as medial knee pain, is one of the most common knee complaints. Several structures sit close together in that area, and the specific location, type of pain, and what triggers it can help narrow down which one is causing trouble. The most common culprits are ligament sprains, meniscus tears, arthritis, and bursitis.
What’s on the Inner Side of Your Knee
The inside of your knee is a busy intersection of soft tissue. A thick band called the medial collateral ligament (MCL) runs along the inner edge, connecting your thighbone to your shinbone and preventing the knee from bending inward. Between those two bones sits a C-shaped pad of cartilage called the medial meniscus, which acts as a shock absorber by spreading the weight of your upper body across the joint surface. Just below the joint line, three tendons merge and attach to the shinbone at a spot called the pes anserine, cushioned by a small fluid-filled sac (a bursa) that reduces friction. A fold of the membrane lining the joint, called a plica, also sits on the inner side.
Any of these structures can become irritated, torn, or inflamed and produce pain that feels like it’s coming from the same general area. What makes diagnosis tricky is that the pain overlaps. Figuring out which structure is involved depends on exactly where the pain sits, how it started, and what movements make it worse.
MCL Sprain
The MCL is the most commonly injured ligament in the knee. It typically gets hurt when the knee is forced inward, such as during a tackle, a skiing fall, or an awkward pivot. You’ll usually know the moment it happens.
A mild sprain (grade 1) causes tenderness along the inner edge of the knee and generally heals within one to three weeks. A moderate sprain (grade 2) produces more intense pain and tenderness along the inner side, often with some swelling and a feeling of looseness when you try to change direction. These take roughly four to six weeks to recover. A severe tear (grade 3) means the ligament is completely torn. Pain is intense, the knee feels unstable, and healing takes six weeks or more. Most MCL injuries, even grade 3 tears, heal without surgery when the knee is braced and followed by progressive strengthening exercises.
Medial Meniscus Tear
A torn meniscus is one of the most frequent knee injuries overall. In younger people it usually results from a twisting motion during sports. In people over 40, the cartilage gradually weakens, and a tear can happen during something as minor as getting up from a chair or squatting in the garden.
The hallmark symptoms are pain that worsens with twisting or rotating the knee, swelling, stiffness, and mechanical symptoms like a catching, clicking, or locking sensation when you try to straighten or bend the leg. Some people describe a feeling of the knee “giving way.” The pain is typically right along the joint line, which you can feel as a crease on the inner side of the knee when it’s slightly bent.
For degenerative tears (the kind that develop gradually in middle age and beyond), the best available evidence strongly supports physical therapy over surgery. Two major clinical trials, METEOR and FIDELITY, compared surgical removal of the torn portion to non-surgical treatment and found surgery was not superior for pain relief or knee function. A third trial, ESCAPE, followed 321 patients aged 45 to 70 for five years and confirmed that 16 sessions of exercise-based physical therapy remained just as effective as surgery. Researchers concluded that removing damaged meniscus tissue may actually speed up joint degeneration over time. Traumatic tears in younger, active people are a different situation and more often benefit from surgical repair.
Knee Osteoarthritis
Osteoarthritis is the gradual wearing down of the cartilage that cushions the joint. The medial compartment (inner side) bears a large share of your body weight during walking, which is why inner-knee arthritis is so common. It develops over years and progresses through recognizable stages.
In the mild stage, you might notice occasional stiffness and aching, especially after sitting for a long time or first thing in the morning, but there’s still enough cartilage to keep the bones from grinding. At the moderate stage, cartilage has significantly thinned. Pain increases during walking, running, squatting, and kneeling, and stiffness after inactivity becomes more pronounced. In the severe stage, cartilage is nearly gone and bone grinds against bone with movement.
If your inner knee pain came on gradually without a specific injury, worsens with activity, and improves somewhat with rest, osteoarthritis is a leading possibility, particularly if you’re over 50 or carry extra body weight. Strengthening the muscles around the knee, maintaining a healthy weight, and staying active with low-impact exercise are the cornerstones of management at every stage.
Pes Anserine Bursitis
This condition causes pain and tenderness on the inside of your knee, but lower than you’d expect. The tender spot sits roughly two to three inches below the joint line, right where the shinbone begins. If you press that area and it’s sore, bursitis is a strong candidate.
It develops from overuse or constant friction on the bursa. Runners are prone to it, especially those who ramp up mileage too quickly, run hills aggressively, or skip stretching. Tight hamstrings are a major contributor. People with knock knees, those who are overweight, and those who already have knee osteoarthritis are also at higher risk. Treatment focuses on rest, ice, stretching the hamstrings, and addressing the training error or biomechanical issue that triggered it.
Plica Syndrome
A plica is a thin fold in the membrane that lines the inside of your knee joint. Most people have four of these folds in each knee and never know they’re there. Sometimes the one on the inner side becomes irritated from repetitive stress, like running or cycling, or from a direct blow such as hitting your knee on a dashboard in a car accident.
Plica syndrome causes pain, swelling, and sometimes a sensation of instability. It’s often confused with a meniscus tear, but there’s a useful distinguishing feature: meniscus pain tends to be right at the joint line, while plica pain is typically above the joint line. Imaging like an MRI is sometimes needed to tell the two apart. Plica syndrome usually responds well to rest, ice, and physical therapy.
How to Tell These Conditions Apart
The location and behavior of the pain are your best clues before you see anyone for a formal evaluation:
- Right along the inner edge, after a specific injury: likely an MCL sprain, especially if the knee feels loose or wobbly.
- At the joint line, with catching or locking: likely a meniscus tear, especially if twisting makes it worse.
- Gradual onset, worsens with activity, improves with rest: likely osteoarthritis, especially in people over 50.
- Below the joint line, about two to three inches down the shinbone: likely pes anserine bursitis, especially in runners or people with tight hamstrings.
- Above the joint line, with repetitive activity: possibly plica syndrome.
A physical exam can further clarify things. One common clinical test for meniscus tears involves bending and rotating the knee to see if it clicks or catches. A meta-analysis found this test is about 70% sensitive and 71% specific, meaning it’s helpful but not definitive on its own. Stress tests that push the knee inward are used to check the MCL. When the diagnosis remains unclear, an MRI can show soft tissue damage in detail.
Signs That Need Urgent Attention
Most inner knee pain improves with rest, ice, and gradual return to activity. But certain symptoms signal something more serious. Get to urgent care or an emergency room if your knee joint looks bent or deformed, you heard a popping sound at the time of injury, you can’t bear weight at all, you have intense pain, or the knee swelled up rapidly. You should also contact your doctor if the knee is badly swollen, red, warm to the touch, or if you have a fever, which can indicate an infection inside the joint.