There are many different causes for knee pain when bending the leg. The location of pain and other symptoms can help differentiate possible causes, such as tendonitis, strains, or arthritis.

The type of knee pain a person has when bending their leg depends on the cause. With osteoarthritis, for example, a person may experience general stiffness. With runner’s knee, they may feel more pain when walking upstairs.

Long-term treatments for knee pain can range from rehabilitative exercises and stretching to surgery and bracing.

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The knee is the largest joint in the body and is a complicated structure. For a person to be able to walk, run, and jump, the knee must be healthy. For this reason, it must have enough support to stabilize its movement, and this support comes from the muscles and tendons.

There are several causes of knee pain. The location of the pain can sometimes help a doctor diagnose the issue.

Patellofemoral syndrome

Many people know patellofemoral syndrome as runner’s knee. Often, overuse is the main cause of pain, which tends to be around the kneecap. Typically, the pain is mild at first and gradually worsens over time. A person may experience a dull, aching pain that increases when going upstairs or bending the leg frequently.

Iliotibial (IT) band syndrome

The IT band is a tendon that runs along the outside of the leg from the hip to the knee. It causes pain after it has become irritated. This can happen when it rubs against the hip or knee after losing elasticity.

Athletes prone to IT band syndrome include basketball players, long-distance runners, and soccer players. A person with IT band syndrome tends to feel pain at the side of the knee.

Patellar tendonitis

Patellar tendinopathy, or jumper’s knee, happens when the patellar tendon develops small tears. Jumpers tend to experience this type of knee pain as jumping puts stress on the patellar or quadriceps tendon.

The patella tendon connects the knee cap to the shin bone, so people often feel pain in the center of the knee when they move their leg.

Hamstring strain

The hamstrings are tendons that attach the hamstring muscles to the pelvis, knee, and lower leg. When a person stretches or overuses the hamstring tendons, they may notice some swelling and pain at the back of the thigh.

People at risk of developing hamstring strain include sprinters, soccer players, or anyone who puts a lot of force on their hamstrings. When someone injures their hamstrings, they may feel pain in the back of the knee, around the buttocks, thigh, and lower leg.

Quadriceps tendon injury

When a person injures their quadriceps, they may have small tears in the tendon. In severe cases, a person may experience a complete tear of the tendon. The quadriceps tendon is above the knee cap and connects the quadriceps muscles to the top of the knee.

People who engage in sports with a lot of jumping, such as basketball players, have a higher risk of quadricep tendon injury. The pain in the knee is typically above the knee cap.

Knee bursitis

The bursa is a small fluid-filled sac that sits around the knee joint. It helps cushion and soften the pressure between the bones, tendons, and muscles around the knee. Bursitis is a term for when the bursa inflames and swells.

The most common cause of knee bursitis is from repetitive kneeling. The pain from bursitis tends to occur around the knee cap in the middle of the knee. Other causes of knee bursitis include injury, diabetes, gout, or a weakened immune system.


Osteoarthritis occurs when the joints break down over time. It is a degenerative disease that can cause joint pain and stiffness in the knee, hips, neck, lower back, and hands.

As the joint degrades, a person may notice more swelling and inflammation in their knee. If these symptoms reduce a person’s ability to stay mobile, they may also develop muscle weakness.

Baker’s cyst

A Baker’s cyst, or popliteal cyst, is a fluid-filled growth behind the knee. The cyst develops when the knee produces too much fluid. Several factors can cause this, including arthritis and a tear in cartilage from trauma. When a person bends their leg, they may notice pain behind the knee and in the leg.

Home remedies for knee pain depend on the cause, but generally, they tend to include:

  • Hot and cold therapy: Warming the knee joint with a hot bath can increase flexibility and blood flow. Cooling the joint with an ice pack helps numb nerves, which reduces pain.
  • Using a cane or walker: An aid can help decrease load on the knee, reducing pain and stress on the joint.
  • Avoiding repetitive movement: Try to avoid movements that repeatedly bend the knee and put pressure on it.
  • Wearing supports: Braces and compression wraps can help support and stabilize the knee.
  • Maintaining a healthy lifestyle: People with knee pain who live with obesity may be able to reduce their symptoms by reducing their body weight. The more a person weighs, the more stress they put on their knee joints, which is a risk factor for osteoarthritis.

A person can use several medical treatments to reduce pain in the knee, such as:

  • Over-the-counter pain relievers and anti-inflammatories: These could be tablets or topical creams.
  • Corticosteroids: Doctors inject these straight into the joint to relieve swelling. These are strong anti-inflammatories, so a doctor will decide how many a person needs at a time.
  • Physical therapy and stretching: If someone has torn a ligament and is an older individual, they may benefit more from physical therapy than surgery. Symptoms of patellofemoral syndrome may also reduce when a person engages in stretching, physical therapy, and rest.
  • Fluid drainage: This treatment is more common in bursitis.
  • Antibiotics: Doctors may treat a knee infection with antibiotics.
  • Surgery: A person only receives surgery when medical professionals have exhausted all other treatment options or if they are not necessary.

A person can contact a doctor when their knee pain does not go away within a few weeks. If, however, the pain has come on suddenly and is very intense, they can go to the emergency room right away, especially if they have injured themselves in an accident.

When pain lasts 3 months or longer, doctors consider it chronic pain, which also requires treatment.

Doctors diagnose the cause of knee pain using several methods, including:

  • physical examinations
  • medical history
  • imaging, including MRIs, X-rays, and ultrasounds
  • lab tests

To prevent knee pain when bending the leg, the guidance is similar regardless of the cause. It is generally advisable for people to try:

  • avoid overusing the knee
  • maintain a moderate weight
  • avoid injuries
  • get plenty of sleep

Knee pain when bending the leg has many causes, including hamstring strain, knee bursitis, and osteoarthritis. There are several home remedies a person can use to ease pain, such as using hot and cold therapy, in addition to resting and wearing a support.

If the pain is a symptom of a more serious condition, such as advanced osteoarthritis or a ruptured tendon, a person may need stronger medications or even surgery. Rehabilitative therapy can also help alleviate knee pain. Doctors typically prescribe this with medication.