Why Does The Inside of My Knee Hurt? | 9 Common Causes and How They Happen

Written By on October 25, 2021 — Medically Reviewed By Kris Ceniza (PT)

Written by on October 25, 2021 — Medically Reviewed By: Kris Ceniza (PT)

The knee is one of the most complex joints in the human body. As such, several things could also make it hurt. But, you might be asking something more specific, like “why does the inside of my knee hurt?”

The easy answer is that it could be something as mundane as a knee contusion. Or, it could be a sign that something else is going on in your body.

There are also several factors that can help you pinpoint the cause of this pain. This includes your lifestyle, age, and health status just to name a few.

In any case, we’ve listed 9 common causes of pain on the inside of the knee. We also included symptoms and risk factors for each cause to make everything easier for you.

9 common causes of medial knee pain

1) Knee contusion

This is your typical bruise. Here, the blood vessels leak out some blood to your injury. Knee contusions are common after a direct hit.

The skin will look red or black at first due to the leak. It will turn purple, blue, and/or yellow over time. It often gets better after a few weeks. Most contusions don’t affect knee movements.

This could be the cause of your knee pain if:

  • A direct blow caused the initial injury.
  • The skin looks black, red, or purple.
  • There’s mild swelling in the area.
  • You can walk as usual.
  • You don’t feel any knee instability.

2) Knee tendonitis

Knee tendonitis is the inflammation of one or more knee tendons. The tendons of three muscles attach to the inner knee:

  • Sartorius.
  • Gracilis.
  • Semitendinosus.

If any of them become irritated, they can cause medial knee pain. They can cause pain behind the knee as well.

The most common cause of knee tendonitis is repetitive use. That’s why it’s a common knee injury in athletes, weekend warriors, or people with physically demanding jobs.

This could be the cause of your knee pain if:

  • Your occupation or hobbies need repetitive lower leg movements.
  • Certain movements make your pain worse.
  • The aching pain appeared gradually and worsened over time.
  • You have difficulty walking and/or climbing stairs.
  • The pain worsens with movement and improves with rest.

3) Medial collateral ligament sprain

The medial collateral ligament (MCL) is one of four major ligaments of the knee. It connects the inside edge of the thigh bone to the shin bone. Along with the other ligaments, it keeps the knee stable.

Knee Force Knee Sleeve

Knee ligament injuries are common in contact sports. An MCL injury can happen if the knee suddenly bends inward. Like after a tackle or a collision in running sports, for example.

A mild MCL sprain takes at least 6 weeks to heal. But, it can take longer depending on the severity of your sprain. (1)

This could be the cause of your knee pain if:

  • You had a recent sports injury.
  • You heard a popping sound at the moment of the knee injury.
  • You felt a sharp pain in the area.
  • You feel knee joint instability.
  • There was rapid swelling during the first 24 hours post-injury.
  • The symptoms are on the inside of the knee.

Related: Reviews for the top knee braces for MCL sprain

4) Medial meniscus injury

Menisci are shock absorbers that protect our knee joints. They also help to keep it stable. We have two menisci in each knee:

A meniscus tear commonly occurs in sports with sudden changes of direction. Like soccer, basketball, or tennis. It can also happen due to aging. The cartilage weakens over time, making it prone to tears.

If the torn meniscus is the medial one, you’ll have pain on the inside of the knee. Other common symptoms include swelling, locking, and stiffness.

Depending on the severity, meniscus tears can take at least 6 weeks to heal.

This could be the cause of your knee pain if:

  • You had a popping sensation at the moment of injury.
  • You feel there’s clicking or popping when bending the knee. Note that the popping should not be there prior to your injury.
  • You have knee stiffness and/or locking.
  • The swelling got worse 2-3 days after the injury.
  • You feel knee instability.

5) Knee joint osteoarthritis

Knee osteoarthritis is the wear and tear of the knee joint. It happens due to aging, but some health issues can speed up this process. (2)

This wear and tear can happen in the joint as a whole. Or, in certain compartments of the knee. If it’s in the medial compartment of the knee, you’ll experience knee pain on the inner side of the joint.

This could be the cause of your knee pain if:

  • You’ve had previous knee conditions. Like a torn meniscus or a severe MCL sprain.
  • You’ve had some kind of knee surgery.
  • You have a BMI >25.
  • You’re +60 years old.
  • The pain has increased gradually.
  • The inner knee pain worsens with movement.
  • It also worsens with lack of exercise.
  • Symptoms improve with rest.

Further reading: Everything you need to know about knee osteoarthritis

6) Rheumatoid arthritis

This is an autoimmune disorder. Its main symptoms are joint pain and swelling. Most of the time, it affects the hands, wrists, knees, and ankles. (3)

Rheumatoid arthritis (RA) can hurt on the inside of your knee. But, most of the time, it affects the whole joint. The treatment of RA consists of medication and home care to reduce the swelling.

This could be the cause of your knee pain if:

  • You have family members with RA.
  • You feel knee stiffness in the morning. It can last several hours.
  • There’s knee swelling without a previous injury.
  • You have knee tenderness.
  • You’re a middle-aged woman.
  • You smoke.
  • Your BMI is >25.

Related: Why do you feel knee stiffness while bending?

7) Synovial plica syndrome

The synovial capsule is what surrounds our joints. It’s a soft, thin tissue that functions as our joints’ lubrication and shock absorber.

But, some people have a thick band of fibrous tissue in some parts of their synovial capsule. This fibrous tissue is called “synovial plica.” It appears during fetal development and as many as 50% of people are born with it. (4)

Synovial plicae aren’t painful themselves. But, they can cause pain if they become irritated due to overuse.

This could be the cause of your knee pain if:

  • You exercised more than usual.
  • You have knee cracking or popping.
  • You don’t have a previous knee injury to explain the pain.
  • Pain worsens when moving the knee.
  • You feel pain at a specific point of the joint.
  • You have weakness in your quadriceps.

8) Pes anserine bursitis

Bursae are small fluid-filled sacs between tendons, muscles, bones, and/or skin. Their main job is reducing the friction between those tissues.

Bursitis happens when there’s swelling of a bursa. They often get swollen due to repetitive movements.

That said, our knees have several of these bursae. One of them is the pes anserine, located on the inside of the joint. This small fluid-filled sac often gets swollen after excessive friction. Or, after a direct impact on the area.

This could be the cause of your knee pain if:

  • You have a lump on the inside of your knee.
  • The lump is warm and/or painful to the touch.
  • There’s inside knee pain when bending or crossing your legs.
  • You had an MCL sprain recently.
  • You have osteoarthritis in the medial compartment of the joint.
  • Your BMI is >25.
  • You have diabetes.

9) Referred knee pain

This means that the origin of the pain isn’t directly related to your knee’s anatomy. Inner knee pain, in particular, often has to do with the lower back.

Knee Force Knee Sleeve

The nerves on our lower back are responsible for the sensation of our legs. So, irritation to any of them can cause referred symptoms. These include severe pain, tingling, and/or weakness in the area the nerve supplies.

If you have any of those symptoms, please seek medical attention.

This could be the cause of your knee pain if:

  • The pain runs from the lower back down to the backside of the thigh. Then, to the inner knee. It can go down to the calf as well.
  • The pain isn’t related to a knee movement most of the time.
  • Some back movements can worsen or ease the pain.
  • You have other symptoms in the area. Like tingling or pins and needles.

Related: What causes knee pain while lying down on your side?

Common treatments for inner knee pain

The treatment options will depend on the cause of the pain. But, most of the time, the treatment includes:

Physical therapy

A physical therapist is a medical professional that helps restore the normal function of your knee. They do this using different treatment methods, including:

  • Passive strategies to reduce pain.
  • Different types of exercises that help enhance the healing process.
  • Recommend a knee brace if you need it to assist your recovery.
  • Identify muscle imbalances to strengthen your leg muscles. This will prevent future injury.

A physio can help you regardless of the cause of your inner knee pain. But, it’s best to find a therapist specializing in your needs. For example, if you’re an athlete, a sports therapist will help you the most.


Most people will do conservative treatments before considering surgery. If they aren’t successful, your doctor may suggest surgery. This is a case-by-case decision, though. Here are some examples in which surgery may help:

  • Advanced osteoarthritis.
  • Recurrent bursitis.
  • Chronic synovial plica syndrome.
  • Athletes that need to get back to sports as soon as possible.


Why does the inside of my knee hurt suddenly?

Common causes of sudden inner knee pain include:

– Muscle cramps.
– A sprain/tear.
– A flare-up of a previous condition.
– A sign of a metabolic disorder.

The cause will depend on your lifestyle, age, genetics, and other factors. It’s best to go to a healthcare provider to check what’s going on.

What does an MCL strain feel like?

You’ll feel pain and swelling on the inner side of the knee. Knee instability can be present as well. You may have heard a popping sound at the moment of injury. It can be painful to walk.

Why does my inner knee hurt?

There are several causes of inner knee pain. It could be a muscle cramp, tendonitis, bursitis, a meniscus or ligament injury, osteoarthritis, metabolic disorders…

That’s why it’s best to go to a doctor. They’ll figure out what’s happening with your knee and how to treat it.

Conclusion: What causes pain on the inside of the knee?

The knee joint is a complex structure. Several things could cause pain on the inner side of the knee joint. A healthcare provider will help you figure out the exact cause. And, more importantly, how to treat it!


  1. Naqvi, Usker et al. Medial Collateral Ligament Knee Injuries. [Updated 2021 Mar17]. Statpearls. From: https://www.ncbi.nlm.nih.gov/books/NBK431095/
  2. Hsu H, Siwiec RM. Knee Osteoarthritis. [Updated 2021 Jul25]. Statpearls. From: https://www.ncbi.nlm.nih.gov/books/NBK507884/
  3. Chauhan K, et al. Rheumatoid Arthritis. [Updated 2021 Jun 29]. Statpearls. From: https://www.ncbi.nlm.nih.gov/books/NBK441999/
  4. Casadei K, Kiel J. Plica Syndrome. [Updated 2021 Jul 25]. Statpearls. From: https://www.ncbi.nlm.nih.gov/books/NBK535362/
Mitch Torres (PT)
Mitch is a physical therapist, personal trainer, and nutrition coach. Fascinated with the knee joint, Mitch poured that passion into writing about knee pain and how to overcome it with movement. His goal is to teach you how to apply this knowledge into your daily life, so you can keep knee pain away for good.