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What causes knee pain? 27 possible conditions

What Is Knee Pain?

Knee pain is a frequent ailment that can be experienced by older adults, young adults, and children. This type of body pain may take place immediately after an injury, or it may appear as an extension of a chronic medical condition. The amount of discomfort people feel may depend on the cause of the pain, area of the knee affected, or their physical condition prior to the pain.

When knee pain occurs in the elderly, it may be a symptom or side effect of another health issue that may directly or indirectly involve the joints and bones. However, this is not always the case. In some older people, the pain can be caused by weakened bone structure that occurs during the aging process.

What Causes Knee Pain?

A number of issues that affect the proper functioning of one or both knees may cause pain. Injury is the most common cause, but other conditions such as arthritis may lead to joint deterioration and discomfort.

Sprains or Strains In the Ligament and Muscle Tissue

These types of injuries often occur when the knee receives blunt trauma or is twisted in the wrong direction. Sprains and strains most often arise during contact sports but may occur during any abrupt or sudden movement.

Damaged Menisci

Menisci are thin layers of cartilage located between the tibia and femur. Resembling a crescent or disc, this connective tissue absorbs most of the stress placed on the lower extremities, but may tear if too much stress is placed on the knees. Menisci also stabilize the knees by preventing abnormal movements that may lead to injury. Tearing of the menisci may interfere with their proper functioning.


Tendinitis is an inflammation that produces redness, tenderness to the touch, and intense pain in the tendons of the knees or any area of the body that have tendons. Activities that require repetitive movements may increase the risk of tendinitis. Other factors for inflamed tendons are poor preparation for exercise and medical conditions such as arthritis.

Osteoarthritis (OA)

OA is a common form of arthritis that may appear in one or more joint bones in the body. It may affect men, women, and children. Women over the age of 55 are at the highest risk for OA. The condition induces pain from the loss of cartilage, which causes the bones to rub together and produce intense discomfort. It may also form from joint malformations present at birth, injuries caused in active sports, or work conditions that require repetitive movements.


Pseudogout, a common type of arthritis in the knees, develops when calcium pyrophosphate crystals (a type of salt) form in the knees’ fluids. Often confused with gout (another condition formed from fluid crystals), pseudogout may be misdiagnosed in some people. It produces painful episodes of swelling and inflammation in the knees as well as other joints.


Inflamed bursae may cause knee pain in some people. Bursae are small pockets of fluid that lubricate the tendons of the hips, shoulders, and knees in order for them to move freely along joints.

Chondromalacia of the Patella

Chondromalacia is a general term used to describe the breakdown or softening of the cartilage found in the body. Chondromalacia of the patella affects only the kneecaps. Damaged kneecaps may become misplaced from constant or persistent use. It often affects females more than males, but may cause bouts of pain for anyone who is very active in life.

High Body Weight

People who are overweight may experience knee pain as they walk or stand. When body weight exceeds normal limits, it may place stress on the joints. The stress may increase the loss of joint tissue as the ends of the tibia and femur rub together and produce friction.

Who Is at Risk For Knee Pain?

Older adults with bone or joint conditions may experience pain in the knees. Women who are over 65 years old may be at a higher risk than those who are younger. Young adults and teenagers may also experience knee pain if they participate in sports or activities that require jumping, running, or similar types of active movements that produce stressful situations on the body.

Children in their teens or preteens may experience pain from active play. The pain is more frequent in children who jump, run, or participate in activities that require repetitive movements.

What Are the Symptoms of Knee Pain?

The symptoms of knee pain may be mild to severe depending on the complexity of the condition or injury.

Common signs and symptoms:

  • stiffness or the inability to bend or straighten the knee(s)
  • skin feels warm to the touch
  • an audible popping, clicking or some other abnormal sound when moving the knee(s)

Serious signs and symptoms:

  • pain accompanied with noticeable swelling, redness, and fever
  • inability to stand
  • limping
  • falling down while attempting to stand
  • feeling numbness in the affected leg (knee)
  • visible signs of injury, such as an abnormal appearance or malformation

How Is Knee Pain Diagnosed?

Physicians may order specific testing or diagnostic methods to locate the cause of pain.

These include:

  • X-rays of the knees to find possible injuries, conditions, and malformations. This type of diagnostic testing uses electromagnetic radiation to see into the body and produce images.
  • Computerized tomography scanning (CT) takes images of the inside of the body at different positions and angles. CT scans may assist with diagnosing problems within joints, bones, and tissues.
  • Ultrasound technology produce images in real-time with the use of high-tech sound waves. This is a technique used for diagnostic purposes.
  • Magnetic resonance imaging (MRI) creates 3-D images of the body. MRI takes a look inside the knee and allows doctors to examine its anatomy.
  • Testing of the joint fluid and any blood found in the knee joints may be used in some cases. A procedure called arthrocentesis is used to examine the fluid taken from the joint capsules, bursae, or synovial membranes.

How Is Knee Pain Treated?

Knee pain treatment includes medications for relieving pain or treating conditions already present. Physical therapy may be ordered for sports-related injuries. Therapy retrains the body to function normally after an injury.

Some people may need injections that contain corticosteroid to improve the symptoms of arthritis. Another type of injection, containing hyaluronic acid (naturally found in the body), is used to provide lubrication for joints that do not produce enough of this acid.

Surgery is an option used for people with severe knee damage that cannot be repaired or rehabilitated. It may include partial or complete knee replacement.

Surgery is not often recommended unless knee pain is truly severe and unmanageable.. This is due to the complications that may occur after the surgical procedure. Some surgical sites may become infected, or a small number of people may experience increased pain until the area completely heals. Age and patient condition may influence these possible complications.

Can Knee Pain Be Prevented?

A healthy diet may help keep the weight down and prevent placing stress on the joints. Warming up the body before lifting weights, running, or doing any other activity that stresses the body may prevent sprains. Resting after strenuous exercises may also help prevent pain in the knees. For people with medical conditions that cause complications in the joints, performing low-impact exercises is ideal.

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See a list of possible causes in order from the most common to the least.


Meniscus Tear of the Knee

The meniscus is a piece of cartilage that provides a cushion between your thighbone (femur) and shinbone (tibia). There are two menisci in each knee joint.

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Runner's Knee

Runner's knee is the common term used to describe any one of several conditions that cause pain around the kneecap (patella).

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Anterior Cruciate Ligament (ACL) Tear

An ACL tear happens when the ligament in your knee that holds the shinbone in place is torn. This type of injury usually occurs in athletes, and may cause bone bruising.

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Posterior Cruciate Ligament Injury

A PCL tear is a tear in the ligament that keeps the knee joint stable. This injury will cause swelling, stiffness, and pain in the knee. Severe tears may require surgery.

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Medial Collateral Ligament Injury of the Knee (MCL Tear)

An injury to the medial collateral ligament (MCL) is often called an MCL sprain. Ligament injuries can either stretch the ligament or tear it.

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This condition is considered a medical emergency. Urgent care may be required.

Since a dislocation means your bone is no longer where it should be, you should treat it as an emergency and seek medical attention as soon as possible.

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Sprains & Strains

Sprains and strains are injuries to the body, often resulting from physical activity. These injuries are common and can range from minor to severe, depending on the incident. Most don't require medical attention.

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This condition is considered a medical emergency. Urgent care may be required.

A fracture is a broken bone that typically occurs when a bone is impacted by more force or pressure than it can support. In an open fracture, the ends of the broken bone tear the skin.

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Sports Injuries

Learn about common injuries that occur in the major regions of the body when playing sports, including concussions, neck strain, torn rotator cuffs, tennis elbow, golfer's elbow, wrist sprains, back pain, hip injuries...

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What is Fibromyalgia?

Fibromyalgia is a chronic disorder characterized by widespread, unexplained pain in tender points in muscles and joints, including the head, neck, and sides of hips.

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Tendons are thick cords that join your muscles to your bones. Tendinitis occurs when tendons become irritated or inflamed. This condition causes acute pain and tenderness, making it difficult to move the affected joint.

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Baker's (Popliteal) Cyst

A popliteal cyst, also known as a Baker's cyst, is a fluid-filled swelling that causes a lump at the back of the knee, leading to restricted movement.

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Ankylosing Spondylitis

Ankylosing spondylitis is a form of arthritis that primarily affects your spine. It causes severe inflammation of the vertebrae that might eventually lead to chronic pain and disability.

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Osteochondroses are a family of disorders that affect the growth of bones in children and adolescents, when bones are still growing. The disruption of blood flow to the joints is often the cause of these disorders.

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What Is Osteoarthritis?

Osteoarthritis, or degenerative joint disease, causes inflammation of the joints in the body. Explore our doctor-reviewed health articles and learn more about osteoarthritis.

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Arthritis is inflammation of the joints (where bones meet) in one or more areas of the body. This condition is most commonly seen in adults, but it can also develop in children and teens.

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Bursitis is an inflammation of the bursae, the fluid-filled sacs that help reduce friction where tendons, skin, and muscle tissues meet bones. Inflammation can cause discomfort and limit range of motion.

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Gout Overview

Gout is a type of arthritis caused by too much uric acid in the blood. When the concentration of uric acid gets too high, sharp urate crystals form and collect in the joints, causing swelling and intense pain.

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Rheumatoid Arthritis Overview

Rheumatoid arthritis (RA) is an autoimmune disease, a disease in which the immune system mistakes the body's own cells for invaders. In RA, the immune system attacks the synovia, the membranes lining the joints.

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Tendon Sheath Inflammation (Tenosynovitis)

Tendons are covered by a protective sheath called synovium, which keeps tendons lubricated. Injury to this area can disrupt this function, causing inflammation.

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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.