Pain on the inner side of the knee is one of the most common knee complaints, and it usually points to one of a handful of conditions affecting the ligaments, cartilage, or soft tissue along the medial (inner) part of the joint. The cause depends a lot on how the pain started, where exactly you feel it, and what makes it worse. Here’s what’s most likely going on and how to narrow it down.
MCL Sprain or Tear
The medial collateral ligament (MCL) runs along the inner edge of your knee, connecting your thighbone to your shinbone. It’s the most commonly injured knee ligament, and damage to it causes pain right along that inner border. MCL injuries typically happen during activities that force the knee sideways, like a direct hit to the outside of the knee, a sudden pivot, or an awkward landing.
MCL tears come in three grades. A grade 1 tear means less than 10% of the ligament fibers are torn. Your knee still feels stable, but you’ll notice tenderness and mild pain on the inside. A grade 2 tear is more significant, and you’ll likely have trouble walking because the knee feels less stable than normal. A grade 3 tear is a complete rupture of the ligament. The knee feels very loose and unstable, with intense pain and tenderness. If you felt a pop on the inner side of your knee during a sport or fall, an MCL injury is high on the list.
Medial Meniscus Tear
Each knee has two C-shaped pads of cartilage (menisci) that cushion the joint. The one on the inner side, the medial meniscus, tears more often than the outer one. You can tear it with a sharp twist or rotation of the knee, but it can also wear down gradually with age and repetitive stress.
The hallmark signs of a medial meniscus tear include pain that gets worse when you twist or rotate your knee, swelling or stiffness, a popping sensation at the time of injury, and a feeling that your knee is locking in place or catching when you try to move it. Some people also feel the knee giving way. One useful distinction: meniscus pain tends to sit right at the joint line, the crease where your thighbone meets your shinbone. If you press along that line and it’s tender, the meniscus is a likely culprit.
Pes Anserine Bursitis
If the pain isn’t right at the joint line but sits about 2 to 3 inches below it, on the inner side of your shinbone, you may be dealing with pes anserine bursitis. This is inflammation of a small fluid-filled sac (bursa) that sits where three tendons from your thigh muscles attach to the upper shin.
This condition is especially common in runners, soccer and tennis players, and anyone whose activities involve repetitive knee bending. Tight hamstrings are a major contributor. So are changes in training intensity, poor stretching habits, knock-kneed alignment, and existing MCL injuries. The pain often flares when climbing stairs, getting out of a chair, or after prolonged activity, and the area may be swollen or tender to the touch.
Medial Plica Syndrome
Inside each knee, a thin membrane lines the joint capsule, and this membrane has natural folds called plicae. Most people have four in each knee. The fold in the middle of the knee can become irritated from overuse, repetitive bending, or a direct blow, leading to pain, swelling, and sometimes a feeling of instability.
Plica syndrome is often mistaken for a meniscus tear because the symptoms overlap. The key difference is location: plica pain tends to sit above the joint line, while meniscus pain is right at the joint line. You might also feel a snapping or clicking sensation when bending and straightening the knee. This condition is more common in people who do activities with lots of repetitive knee flexion, like cycling or stair climbing.
Osteoarthritis of the Inner Knee
If your inner knee pain has developed gradually over months or years, especially if you’re over 50, osteoarthritis in the medial compartment of the knee is a strong possibility. This is the most common location for knee arthritis because the inner side of the joint bears more of your body weight during walking.
The cartilage on the inner side wears down over time, narrowing the space between the bones. In advanced cases, this progresses to what’s described as a “bone-on-bone” appearance on X-rays. You’ll typically notice stiffness after sitting for a while, pain that worsens with activity and improves with rest, and a gradual loss of range of motion. Some people develop a bowed-leg alignment as the inner compartment wears unevenly. Standing X-rays are the standard way to evaluate this, because they show cartilage loss more accurately than X-rays taken while lying down.
How to Tell These Conditions Apart
The location of your pain is the single most useful clue. Pain right along the inner edge of the knee suggests the MCL. Pain at the joint line, where the bones meet, points toward the meniscus. Pain 2 to 3 inches below the joint on the shinbone is characteristic of pes anserine bursitis. Pain above the joint line suggests the plica.
How the pain started matters too. A sudden onset during a twist, fall, or impact suggests a ligament or meniscus injury. Pain that crept in gradually over weeks, especially after increasing your activity level, is more typical of bursitis, plica syndrome, or early arthritis. Mechanical symptoms like locking, catching, or the knee giving way strongly suggest a meniscus tear.
Healthcare providers use specific physical tests to sort these out. For a suspected MCL injury, they’ll press on the outside of your knee while it’s slightly bent (a valgus stress test) to see if the inner side opens up more than it should. For a meniscus tear, they’ll bend your knee to 90 degrees and rotate it inward and outward while slowly straightening it (a McMurray test), feeling for clicks or pain that indicate cartilage damage.
What Helps and What to Expect
Most causes of inner knee pain respond well to conservative treatment, at least initially. Rest, ice, compression, and keeping the knee elevated reduce swelling in the first few days. Avoiding the specific activity that triggered the pain prevents further irritation.
For bursitis and plica syndrome, stretching tight hamstrings and strengthening the muscles around the knee (particularly the quadriceps and hip stabilizers) often resolves the problem over several weeks. Correcting training errors, like ramping up mileage too quickly or skipping warmups, prevents recurrence.
MCL injuries heal without surgery in most cases because the ligament has a good blood supply. A mild grade 1 sprain typically resolves within a couple of weeks with rest and gradual return to activity. More severe tears take longer, and a grade 3 complete tear may require bracing for several weeks and a structured rehabilitation program. Meniscus tears are more variable. Small tears in younger people sometimes heal with rest, but tears that cause persistent locking or catching often need arthroscopic surgery to trim or repair the damaged cartilage.
Osteoarthritis doesn’t reverse, but it can be managed effectively for years. Weight loss (even 10 to 15 pounds) significantly reduces stress on the inner compartment. Strengthening exercises, low-impact activities like swimming or cycling, and anti-inflammatory medications control symptoms for most people. When the cartilage is completely gone and pain limits daily life, knee replacement becomes an option.
Signs That Need Prompt Attention
If you can’t put weight on the knee or can’t move it at all, don’t try to push through it. This warrants a same-day medical evaluation. Inner knee pain that persists for more than a few days, is bad enough to disrupt your daily routine, or makes it hard to walk also deserves a visit to your provider. If the knee is visibly deformed, severely swollen within hours of an injury, or the pain followed a serious fall or car accident, go to the emergency room to rule out a fracture or complex ligament injury.