What Causes Knee Pain?

Knee pain is common, affecting about one in four adults. It accounts for almost 4 million primary care visits each year. Although many suffer from knee pain, it is still essential to determine the root cause. 

Onset may be sudden or chronic, and causes of knee pain range from minor to severe. Many issues are treatable. Pain relief is available, and treatment may significantly improve your quality of life.

Health Report Live provides quality information to seniors who want to understand what may be afflicting them and how to get past it.

This article will discuss common causes of knee pain, prevention, risk factors, treatment and pain relief, knowing when knee pain is serious, and when you may start to feel better.

Causes of Knee Pain 

The most common causes of knee pain are knee joint degeneration that occurs with age, athletic injuries, and repeated stress and overuse of the knee joint. 

Common sports injuries may include:

  • Sprains and strains
  • Knee ligament injuries
  • Torn knee cartilage
  • Meniscus tears
  • Kneecap dislocation
  • Patellofemoral pain syndrome (also known as runner’s knee) 

Chronic conditions that may produce knee pain include tendinitis, bursitis, iliotibial band syndrome, the presence of a baker’s cyst, knee arthritis, osteoarthritis, rheumatoid arthritis, gout, and tumors.

What Does a Knee Injury Feel Like?

Symptoms may vary depending on the knee injury; however, many have similarities. You might not be able to decipher what type of injury has occurred without speaking to a health care practitioner. 

Ligament injuries may cause a popping noise accompanied by leg buckling and swelling. 

Knee joint dislocation injuries may be painful, tender, and swollen. The kneecap may be visibly displaced to the side or with other deformities. You may not be able to unbend your affected leg or walk properly on the affected side. 

Knee cartilage injuries, such as meniscus tears, may cause pain, stiffness, swelling, instability, decreased range of motion, and catching or locking sensation in the knee joint.


The Journal of Orthopaedic and Sports Physical Therapy (JOSPT) claims that participating in knee-health-oriented running drills, strength training, core exercises, plyometrics, and stretches helps prevent knee injuries. 

Other preventative methods include:

  • Maintaining a healthy weight
  • Striving for the best possible technique and posture while exercising
  • Ensuring that your body is in the proper physical shape to play sports safely
  • Limit high-impact exercise by substituting it with low-impact exercises, such as swimming


There are many potentialities as to what causes knee pain. Some causes are chronic issues, while others are acute knee injuries. 

Knee Arthritis

Knee arthritis is the degeneration and inflammation of knee joint cartilage. As the cartilage deteriorates, the space between the bones becomes smaller. 

This condition can eventually cause the bone to rub against bone, creating bone spurs. The knee may become stiff and painful to move.

Rheumatoid arthritis and osteoarthritis are both types of arthritis that may affect the knee joint. Rheumatoid arthritis is an autoimmune disease that may affect multiple joints. Osteoarthritis is the most common type of arthritis that affects the knee. Knee osteoarthritis is caused by gradual knee joint degeneration.

Knee Ligament Injuries

Four main ligaments help keep the kneecap stabilized. These include the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL).

You may hear a popping sound for cruciate ligament injuries, followed by the affected leg buckling and swelling. They do not always cause pain. 

Commonly injured cruciate ligaments are the anterior cruciate ligament (ACL), located in the center of the knee, and the posterior cruciate ligament (PCL), located in the back of the knee. 

A rapid twisting movement often causes ACL injuries. PCL injuries commonly occur with sudden, direct impact.

Medial collateral ligament (MCL) injuries are more common than LCL injuries. Both are frequently sports injuries.


Knee bursitis may cause pain and limit your mobility. 

The bursae surrounding the knee can become inflamed due to overuse, pressure on the knee (such as an extended period in a kneeling position), trauma, a bacterial infection of a bursa, or complications from other underlying medical conditions.


Infection of the knee joint is a potentially severe condition that may not only locally affect the knee. 

Septic arthritis, which refers to joint infection, is a bacterial or fungal infection of a joint that causes inflammation. Symptoms include severe pain with movement of the knee joint, swelling, fever, and redness.

Iliotibial Band Syndrome

This occurs when the iliotibial band (IT band), which runs the exterior hip to the knee, becomes overly tense and rubs against the outside of the thighbone (femur). This can cause knee pain.

It is a common ailment for distance runners but can occur in anyone.

Hip, Foot or Ankle Problems

If you have hip, foot, or ankle problems, it could change how you stand or walk. An altered gait may lead to knee pain, which puts undue stress on the knee joint.

Physical therapy exercises may help to resolve this, depending on the initial issue.

Past Injuries

Previous knee injuries may potentially cause permanent damage to and weaken the knee joint, which is what causes knee pain. A past injury also puts you at higher risk for re-injury. The risk can be reduced with preventative exercises and techniques.

Cancer and Knee Pain

The most common symptom of osteosarcoma is pain and swelling at the tumor’s location within the bone. The knee and upper arm are frequent sites for this type of cancer; osteosarcoma can impact mobility.

Torn Knee Cartilage (Meniscus)

The menisci are two discs of cartilage that act as shock absorbers for the knee. Meniscal tears are frequently seen in athletes who play contact sports and in cases where the knee joint has degenerative issues. 

Patellar Tendonitis and Tear

Patellar tendonitis (inflammation and irritation of the patellar tendon) may be caused by overuse or an acute injury. Patellar tendonitis weakens the tendon and can lead to tears, causing pain at the front of the knee.

Patellofemoral Pain Syndrome

Patellofemoral pain syndrome pertains to pain that occurs between the kneecap and the thighbone. It affects individuals of any age and is a widespread cause of pain in the front of the knee. Squatting or going downstairs are common causes of knee pain related to this syndrome.

Osgood-Schlatter’s Disease

Osgood-Schlatter’s disease often occurs in boys who play sports between 10 and 15 years old. Painful swelling forms where the patellar tendon connects with the shinbone (tibia). 

This condition generally resolves independently with rest and at-home treatments over time. One or both knees can be affected.

Other Common Causes

Several other common causes of knee pain include:

  • Chondromalacia patella, the degeneration of cartilage under the kneecap
  • Sprains and strains
  • Kneecap fractures, which are often caused by blunt trauma
  • Gout and pseudogout

Less Common Causes of Knee Pain

Several other less common causes of knee pain include:

  • Arthrofibrosis, where adhesions cause restricted movement and pain
  • Hoffa’s Syndrome, which leads to despair at the front of the knee
  • Saphenous Nerve Palsy

What Is the Most Common Reason for Knee Pain?

The most common causes of knee pain are deterioration of the knee joint over time, direct injury, or overuse of (or sustained pressure on) the knees. 

What Is the Reason for Knee Pain Without Injury?

There are various possibilities of what causes knee pain without injury:

  • Chronic issues such as knee arthritis, rheumatoid arthritis, patellofemoral pain syndrome, and Iliotibial band syndrome
  • Past knee injuries
  • Overuse
  • Weakness and instability
  • Tightness in surrounding muscles
  • Age-related degeneration
  • Infection
  • Bursitis

Risk Factors

Risk factors vary per condition that causes knee pain. 

Some of the top risk factors include being overweight or obese, as it puts additional stress on all body joints, previous knee injuries, participating in certain sports or occupations, and not having enough muscle strength or flexibility.

How Do I Know if My Knee Pain Is Severe?

Knee problems that present with intense pain, swelling, redness or change of skin color, and fever may be signs of a severe infection. 

Acute knee injuries that present with knee joint deformity or a popping noise at the time of damage may also be severe. If you cannot hold weight on the afflicted leg, medical treatment may be necessary.

Chronic knee pain may be severe if it significantly impacts your daily life and coincides with other systemic issues.

If you are unsure of the gravity of what causes knee pain, contact your health care provider.

What Can You Do for the Pain?

At-home options to help provide pain relief include:

  • Over-the-counter, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (under the brand names Advil and Motrin) or naproxen (under the brand name Aleve)
  • Acetaminophen (under the brand name Tylenol) may also provide pain relief but does not have anti-inflammatory properties
  • The application of topical pain relief creams, such as diclofenac (commonly sold under the brand Voltaren Gel and Pennsaid)
  • Anti-inflammatory supplements such as glucosamine, chondroitin, and turmeric (for those with less severe pain)

Aside from surgery, your orthopedic doctor can assist you with pain relief treatments such as:

  • Corticosteroid injections
  • Hyaluronic acid injections
  • Platelet-rich plasma (PRP)

When Should I See a Pain Management Specialist?

If you have chronic (lasting more than three months) severe pain that impacts your day-to-day activities, your doctor may recommend scheduling an appointment with a pain management specialist. 

Your doctor may prescribe medications, order further testing, use technology that interferes with pain transmission, implement a physical therapy routine, and/or refer you to a pain psychologist.


A health care provider may first need to perform a physical examination to diagnose the cause of your knee pain before you can proceed with treatment.

Some knee problems may be treated at home, and others require medical intervention, such as surgery and prescribed medication.

Home Care

Self-care treatments for acute knee injuries may include the following: 

  • Over-the-counter pain relief and anti-inflammatory medications, such as ibuprofen and topical creams
  • At-home physical therapy exercises
  • Rest
  • Ice
  • Heat
  • Compression
  • Elevation 

At night, your doctor may also recommend sleeping with a pillow underneath your knees.

  • Wearing a knee brace, bandage, or sleeve for support

If you are overweight, your health care provider may recommend losing weight, as it increases stress on the knee joint.

Your doctor may recommend orthotics or other shoe inserts if what causes knee pain is an anatomical or structural issue.

Substituting high impact exercise for low impact exercise, such as swimming, water aerobics, and bicycling, reduces stress on the joints and may help lessen knee joint pain. 

If you are a runner and still choose to participate, make sure to have the proper shoes and run on a flat, cushioned surface, such as a track.

Physical Therapy

Physical therapy exercises help to improve your range of motion, regain mobility, increase flexibility, strengthen, and reduce pain. 

Always make sure to stretch before exercising and cool down afterward. 


Medications used to treat general knee pain include oral and topical NSAIDs and corticosteroid injections.

If what causes knee pain is an infection or systemic disease (such as rheumatoid arthritis), your healthcare provider may prescribe other medications to facilitate recovery and manage pain.

Complementary and Alternative Therapies

Complementary and alternative therapies may include:

  • Massage and stretch sessions
  • Yoga
  • Chiropractic adjustments
  • Exercise
    • Working with a fitness trainer to strengthen weak areas of the body
    • Physical therapy exercises
  • Tai Chi
  • Acupuncture
  • Reiki


If your doctor deems surgery necessary, there are several types that they may discuss with you:

  • Arthroscopic surgery
    • Involves the use of small incisions and the use of a fiber-optic camera
  • Partial or total knee replacement surgery
    • The most damaged parts of the knee or the entire knee joint are replaced with surgical-grade metals and plastics.
  • Osteotomy
    • Bone is taken from the shinbone or thighbone to help fix alignment and relieve knee arthritis pain.

When to Contact a Medical Professional

If you have been experiencing chronic, unresolved knee pain and/or restriction of movement, you may want to schedule an appointment with your health care provider. Your doctor will be able to inform you of the best treatment method and help you manage long-term care.

For potentially acute severe injuries, contact a medical professional immediately (or head to the urgent care or hospital) if you experience any following symptoms.

  • Severe pain
  • Notable swelling
  • Redness
  • Warmth and tenderness around the knee joint
  • Fever
  • Knee joint deformity 
  • A popping sound upon injury
  • Inability to hold weight on the affected leg

What to Expect at Your Office Visit

Your health care provider will perform a physical examination that focuses on your affected knee. They will look for visual signs of injury, such as redness, swelling, and tenderness, and check your range of motion. 

Your health care provider may also order diagnostic tests, such as X-rays, MRI, CT scans, or ultrasound, depending on what they suspect to be the source of pain.

Your doctor may refer you to an orthopedic doctor, sports medicine specialist, or podiatrist if they deem it necessary.

When Will My Knee Feel Better?

The prognosis depends on the root cause. It is essential to contact your health care provider to find out what causes knee pain and begin a treatment course promptly.

For more information on what causes knee pain, Health Report Live has further resources for seniors looking to change their quality of life and resolve knee pain:

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Sean Byers, MD

Sean Byers, MD

Sean Byers is currently a Resident in the Internal Medicine program at UTMB. He studied at the University of Queensland School of Medicine as well as received his Master’s in Public Health with a focus in epidemiology and biostatistics at the University of Southern California. His background is in biology, computer science, public health, and internal medicine.

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  5. Meniscus Tears https://orthoinfo.aaos.org/en/diseases--conditions/meniscus-tears/
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