The knee is a complex body part: it’s made up of bones, cartilage, ligaments and tendons that are prone to straining or tearing. Moreover, the knee is one of the largest joints in the body and, therefore, there’s a lot of room for error.

One of the most common complaints in adults is knee pain. The culprits of knee pain can be as simple as overuse of the joint or as complex as a chronic condition, such as arthritis.

Below, we discuss 10 reasons you might be experiencing pain behind your knee, and what to do about it.

1. Leg cramps

When your muscle tightens, this produces a cramp-like sensation. When you’re experiencing a cramp behind your knee, it could be caused by dehydration, nerve problems in your legs, infections, toxins or possibly even liver disease.

Leg cramps, however, can be soothed in the moment or prevented in general. If you’re experiencing one of the less severe types of knee cramps, here are some remedies for dealing with them.

2. Baker’s cyst

Normally, synovial fluid acts as a lubricant for your knee joint. A Baker’s cyst forms when too much synovial fluid is produced and leads to a fluid-filled sac behind the knee.

According to HealthLine, Baker’s cysts can be caused by arthritis or a knee injury and symptoms can include pain, swelling and stiffness. Sometimes, a Baker’s cyst can go away by itself. However, for larger or more painful cysts, steroid injections, physical therapy or cyst drainage may be needed.

3. Iliotibial Band Syndrome

The iliotibial band (IT band) is a ligament that runs along the outside of your thigh. When it rubs against the the bone, it can get swollen and irritated, leading to IT band syndrome.

IT band syndrome is typically caused by exercise. In this case, resting the affected area and letting it heal is the best course of treatment.

4. Osteoarthritis

Osteoarthritis (OA) is a very prevalent condition in older adults, leading to pain, swelling and stiffness in the knee joints.

This “wear and tear” form of arthritis is caused by damage or breakdown of joint cartilage that’s between bones and can cause limitations to an individual’s range of movement.

However, there are ways to manage OA using gentle movement. For example: yoga, swimming or getting on the stationary bike at the gym might help calm intrusive OA symptoms.

5. Inflammatory Arthritis

Another source of knee pain can be inflammatory arthritis (like rheumatoid arthritis, lupus or psoriatic arthritis). Preventative medicine can help manage symptoms of arthritis and prevent further joint damage.

If you have inflammatory arthritis, you might be prescribed nonsteroidal anti-inflammatory (NSAID) drugs to help reduce inflammation and relieve joint pain. Furthermore, steroids such as prednisone can also be used to reduce inflammation and slow joint damage. However, steroids are typically not a long-term solution.

6. Bursitis

Bursitis is a condition that causes swelling, stiffness and warmth/tenderness of the knee. This is typically due to overexertion of the joints.

Bursitis happens when small, fluid-filled sacks (known as “bursa”) that usually cushion the knee become swollen and irritated.

According to MedlinePlus, bursitis treatment includes rest, ice and pain medicines. If these treatments don’t provide relief, your doctor may inject a drug into the area surrounding the swollen bursa.

7. Torn meniscus

A meniscus tear can be caused by a sudden twist or pivot of the knee — especially if your full weight goes into it. According to WebMD, menisci are more susceptible to tears due to aging and arthritis.

Torn menisci can lead to stiffness, swelling and difficulty with range of motion in the knee joint. Treatment of this condition can include conservative management (rest, ice, compression and elevation), physical therapy or surgery.

8. Infection

When bacteria contaminate the lubricating synovial fluid of the knee, a septic joint can occur. According to Healthline, knee infections sometimes happen as a complication of surgery or inflammation.

A knee infection is serious and often will need immediate and aggressive treatment. Treatment for a knee infection will vary widely depending on the underlying cause.

9. Gout and pseudogout

Gout and pseudogout are similar conditions: Gout is due to a buildup of uric acid, while pseudogout is caused by calcium pyrophosphate. When crystals gather in the joint, gout occurs.

Though gout often affects the big toe most prominently, knee pain can also accompany the condition. The knee pain and swelling can be very intense and come with stiffness, redness, and heat.

10. Referred pain

Sometimes your actual knee won’t even be the culprit behind your knee pain. Referred pain is when pain somewhere else is what’s making your knee sore or uncomfortable. For example, pain in your back, hip or foot can radiate into your knee when nerves shift, and your brain isn’t sure what the source of the pain actually is.

Though, in this case, your knee pain will feel very real. You’ll have to address the root of the problem in order to quell it.