Pain on the inside of the knee is known as medial knee pain. It is most commonly caused by caused by a sudden trauma (acute knee injury), but can also develop gradually through overuse or poor lower limb biomechanics.
Medial knee ligament sprain
An MCL sprain is a tear to the ligament on the inside of the knee joint. It is caused either by a direct impact to the outside of the knee or from twisting. Symptoms include
- Sudden onset pain located on the inside of the knee.
- Rapid swelling.
- Medial knee ligament injuries are graded from one to three depending on the severity.
- Often they will occur in conjunction with a medial cartilage meniscus injury.
Read more on MCL sprain.
Medial meniscus injury
A torn meniscus is a tear of the semi-circular cartilage in the knee joint. It is commonly injured through direct impact in contact sports or twisting, but can also occur in older athletes through gradual degeneration. Symptoms include:
- Pain on the inside of the knee which may be of sudden onset but can also occur gradually.
- The patient will usually experience pain when fully bending the knee or squatting down.
- There may be swelling present but not always.
- The patient may also complain of the knee locking or giving way.
- There will be tenderness along the joint line.
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Patellofemoral Pain Syndrome (PFPS) is a generic term used to describe pain at the front of the knee around the patella (kneecap). Symptoms include
- An aching pain in the knee join, particularly at the front of the knee around and under the patella.
- There is often tenderness along the inside border of the kneecap.
- Swelling will sometimes occur after exercise.
- Patellofemoral pain is often worse when walking up and down hills or sitting for long periods of time.
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A synovial plica is a fold in the synovial membrane which encloses the knee joint. The plica is found along the inside of the kneecap. It is sometimes confused with, or misdiagnosed as patellofemoral pain syndrome as the symptoms can be similar:
- Pain and discomfort on the inside of the knee.
- A sharp pain at the front inside edge of the kneecap.
- Symptoms may also occur towards the back of the patella.
- You will likely feel a sharp pain when squatting.
- A synovial plica may sometimes feel like a thickened band under the inside of the kneecap.
Read more on Synovial plica.
Pes anserine bursitis/tendinopathy
This is one of the less common causes of pain on the inside of the knee. The pes anserine is the point on the inside of the knee where the tendons of three muscles combine and insert.
- The bursa which lies under the tendon can become inflamed through overuse.
- The tendon may also become inflamed, or more likely degenerate if your injury is chronic.
- Pes Anserine Tendonitis is often difficult to distinguish from a medial ligament injury. This is because the symptoms are similar and both are likely to be painful when stressing the inside of the knee.
Read more on Pes anserine bursitis/tendinopathy.
Osteoarthritis of the knee
Osteoarthritis is a common cause of knee pain and usually affects people over fifty years old. It occurs when cartilage which protects the bones degenerates.
- Pain develops gradually over time and often causes stiffness and sometimes swelling.
- Symptoms start as a deep aching pain in the inner knee which is worse after exercise.
- Stiffness in the joint is common, particularly in the morning, however, this may reduce with movement as the joint produces lubricating synovial fluid.
- Sometimes a clicking or cracking noises are heard when moving the knee.
Read more on Osteoarthritis of the knee.
Referred knee pain
Pain on the inside of the knee can result from injuries or conditions elsewhere, especially, in the hip and lower back. The sciatic nerve gets pinched or compressed radiating pain down the leg.
Read more on sciatica.
Other causes of medial knee pain in young athletes include:
- Slipped capital femoral epiphysis (hip)
- Perthes’ disease (hip)