What is knee pain?
The knee is the joint where the kneecap (patella), thigh bone (femur), and bones of the lower leg (tibia and fibula) meet. Your knees also consist of skin, muscles, tendons, cartilage, ligaments, nerves, and blood vessels, all of which are subject to injury, infection, and other conditions that can cause knee pain.
Ligaments hold together the bones that make up the knee joint. Cartilage is a protective, slippery tissue that covers the ends of bones and allows the knee joint to move smoothly. Nerves control sensation and movement, and blood vessels ensure continuous blood circulation to and from the knees and legs. Healthy knees ensure stability and flexibility of the leg and enable movement of the lower leg. Knee pain can seriously affect your life and is one of the most common reasons for doctor visits.
Knee pain can be acute, develop suddenly, and disappear quickly, or it may build gradually over a long period of time. Chronic knee pain can last for several weeks to months or longer. Knee pain may feel dull and achy, throbbing, piercing, or tingling. You may also experience knee stiffness or paresthesia—pain-like sensations often described as pins and needles, prickling, or burning. Knee pain may be simply irritating and uncomfortable or so debilitating that you cannot put weight on your leg or walk.
The severity of knee pain may vary, depending on the cause. Causes of knee pain include a very wide variety of conditions including normal growth and aging. Knee pain caused by a minor sprain or contusion may disappear with home treatments, such as rest, ice, elevation of the leg, and medications.
In some cases, knee pain may be caused by a serious or life-threatening condition, such as deep vein thrombosis, knee infection, fracture, or dislocation. Seek immediate medical care (call 911) if you, or someone you are with, have difficulty moving the leg or walking; deformity of the knee, lower leg, or thigh; severe pain; severe swelling; or color changes in the knee or leg.
What are the types of knee pain?
Knee pain varies greatly depending on the cause. It can range in severity, as well as the specific sensation, such as dullness or sharpness. Sounds can also accompany different kinds of knee pain. Some common types of knee pain include:
- Knee pain when kneeling: This kind of knee pain is often a sign of bursitis. Bursae are fluid-filled sacs inside certain joints, including the knee. They provide cushioning when you kneel or bend your knee. Bursitis occurs when bursae become inflamed or irritated.
- Knee pain with crepitus: Crepitus is the medical term for joint sounds, such as creaking, crunching or cracking. Alone, it is usually harmless. When it occurs with knee pain, it could be a sign of an injury, such as a meniscus tear. (The meniscus is cartilage.)
- Knee pain on the stairs: Pain when you climb the stairs can be an early sign of osteoarthritis (OA). OA is a degenerative condition that also causes joint stiffness and limited movement.
- Morning knee pain that resolves: When you wake to joint pain that improves during the day, it can be a sign of arthritis. In particular, it’s common with autoimmune problems, such as rheumatoid arthritis and lupus. OA can also cause morning knee pain, but it usually resolves soon after you get up and move.
- Patellofemoral pain syndrome: The common name for this type of knee pain is runner’s knee or jumper’s knee. It causes dull pain around the kneecap with activity. It’s commonly the result of overuse or repetitive stress injury.
- Popping knee pain: When knee pain follows a noticeable pop or snap, it could be a sign of an acute injury. An ACL (anterior cruciate ligament) injury, such as a torn ACL, commonly causes this type of sound and sensation. Severe pain usually follows quickly.
- Sudden, severe morning knee pain: If you go to bed feeling fine and wake up with severe knee pain, it could be a sign of gout. Gout flares can also cause redness and warmth over the joint.
What other symptoms might occur with knee pain?
Knee pain can develop along with other symptoms, which vary depending on the underlying disease, disorder or condition. Additional symptoms can involve other body systems or areas, such as the cardiovascular and neurological systems.
Other symptoms that may accompany knee pain include:
- Bruising, laceration or abrasion
- Burning or prickling feeling
- Change in gait such as limping
- Inability to flex or straighten the knee
- Muscle spasms
- Redness, warmth in joint
- Reduced range of motion or knee stiffness
- Thigh, lower leg, ankle, or hip pain
- Tingling, pain, or other abnormal sensations in the toes
Symptoms that might indicate a serious or life-threatening condition
In some cases, knee pain may occur with other symptoms that might indicate a serious or life-threatening condition, such as deep vein thrombosis, which is a blood clot in the leg that can travel to the lungs and cause a life-threatening pulmonary embolism. Other serious conditions include fracture, dislocation or infection.
Seek immediate medical care (call 911) if you, or someone you are with, have other serious symptoms, with or without knee pain, including:
- Change in consciousness or alertness, such as fainting
- Chest pain
- Discolored, unusually pale or cold leg
- Inability to walk or put weight on your leg
- Popping sound at time of injury
- Red streaks around a tender area or lump
- Red, warm and swollen area of the leg
- Severe pain
- Severe swelling or deformity of the knee, lower leg, or thigh
What causes knee pain?
There are many diseases and conditions that can cause knee pain, but the leading causes are typically related to physical activity, such as overuse, injury, and age-related wear and tear on the muscles, cartilage, tendons and ligaments of the knee.
Trauma- and injury-related causes of knee pain
Knee pain may be caused by injuries and trauma-related problems including:
- Bleeding within the joint space (hemarthrosis)
- Bone fracture (broken bone) or knee dislocation, especially of the patella (kneecap)
- Bursitis (also described as “housemaid’s knee,” which is caused by kneeling on hard surfaces, leading to inflammation of the sacs cushioning the knee)
- Fragments of bone or cartilage within the joint space
- Laceration, abrasion or contusion of the knee
- Ligament sprains and tears, especially of the anterior cruciate ligament (ACL) and medial collateral ligament (MCL) of the knee, which ensure leg and knee stability
- Meniscus tear (tear in the shock-absorbing cartilage of the knee)
- Osgood-Schlatter disease (painful swelling of the anterior tibial tubercle, the bump on the front, upper part of the lower leg bone, that occurs in growing adolescents due to overuse)
- Runner’s knee (kneecap pain usually due to overuse or injury)
- Tendinitis (inflammation or irritation of tendons due to overuse or injury), such as patellar tendinitis
- Tendon avulsion or fracture (tendon rupture or pulling away from the bone), such as that of the biceps femoris tendon or the quadriceps tendon
Infectious causes of knee pain
Knee pain can be caused by various infections including:
- Cellulitis (invasive infection of the skin and surrounding tissues)
- Infection of a knee wound or sore
- Infection of the knee joint (septic arthritis)
- Osteomyelitis (bone infection)
Neurological causes of knee pain
Knee pain can be caused by neurological conditions that cause inflammation, entrapment, compression or damage to the nerves including:
- Peripheral neuropathy (disorder that causes damage and dysfunction of nerves that lie outside the brain and spinal cord) and diabetic neuropathy (neuropathy caused by long-term diabetes)
- Piriformis syndrome (buttock muscle compressing or irritating the sciatic nerve, causing pain, tingling or numbness down the leg)
- Sciatica (compression, injury or inflammation of the sciatic nerve, which causes burning or shooting pain running from the buttocks down the back of the leg)
Other causes of knee pain
Other causes of knee pain include:
- Arthritis including osteoarthritis, rheumatoid arthritis, and gout
- Baker’s cyst (fluid-filled cyst behind the knee)
- Certain connective tissue disorders such as lupus
- Deep vein thrombosis (blood clot in the leg that can break loose from the leg, causing a pulmonary embolism in the lung)
- Fibromyalgia (chronic condition causing widespread muscular pain, stiffness and tenderness)
- Retained foreign body after surgery
When should you see a doctor for knee pain?
Minor knee pain often gets better with self-care. But there are times when it’s best to see a doctor about knee pain. Make an appointment with your doctor if you have mild knee pain that persists for more than a couple of weeks. This includes knee pain that comes and goes over the course of two weeks.
See a doctor promptly when:
- Knee pain occurs with knee buckling or locking
- Knee pain prevents you from fully bending or extending the knee
- Moderate knee pain lasts for more than three days with self-care
Call 911 or go to your nearest emergency room for knee pain when:
- There is obvious knee or leg deformity.
- You cannot bear weight on the affected leg or bend the knee at all.
- You have a fever or redness, swelling and warmth around the knee.
- You have numbness in the toes, foot, or lower leg.
- You have severe knee pain without putting weight on the leg.
- You have sustained a knee injury or any kind of trauma to the knee.
How do doctors diagnose the cause of knee pain?
To diagnose your condition, your doctor or licensed healthcare provider will ask you several questions related to your symptoms including:
- In what part of the knee do you feel pain?
- When did the pain start?
- How long does the pain last?
- Describe the pain. It is sharp or dull, throbbing or aching, constant or occasional?
- Are there any activities that cause the pain?
- Are you experiencing any other symptoms, such as tingling?
- Are any other joints painful?
Your doctor will also perform a physical exam, focusing on your knee and leg. The exam will check for signs of injury and may involve moving your knee in different directions to see how far it will go. After the exam, your doctor may recommend imaging tests, such as X-rays, ultrasounds, CT (computerized tomography) scans, or MRIs (magnetic resonance imaging). If your doctor suspects an autoimmune problem or infection, blood tests may be necessary.
It is not always possible to diagnose an underlying cause or condition. If the problem persists and your provider is unable to determine a cause, seeking a second opinion may give you more information and answers.
How do you treat knee pain?
Knee pain treatment will depend on the cause and the severity of the pain. The goals of treatment are to relieve the pain and correct any underlying problem. For many types of knee pain, doctors start with conservative treatments first. This includes:
- Bracing to immobilize, support and stabilize the knee
- Crutches to keep weight off the knee if necessary
- NSAIDs (nonsteroidal anti-inflammatory drugs), such as ibuprofen (Advil, Motrin) and naproxen (Aleve), which can help relieve pain and swelling
- Rest, ice and elevation to relieve pain and reduce swelling due to minor injuries
Physical therapy is a common method of fixing knee pain. It can help strengthen supporting muscles and restore knee function. If all of these efforts fail to improve knee pain, joint injections may provide relief. Doctors may ultimately recommend surgery, such as knee arthroscopy, depending on the cause of knee pain.
Exercises to fix knee pain
Knee pain stretches and exercises are part of a comprehensive treatment plan for many people. The goal is to keep supporting muscles strong and flexible. Doing so will keep the knee stable, which can relieve pain. It will also help prevent future knee injuries.
Common leg exercises for knee pain include:
- Hamstring curls
- Lateral leg raises
- Leg lifts and leg dips
- Step ups
- Toe raises
- Wall squats
For healthy muscles, it’s just as important to stretch them, especially after exercise. When muscles are tight, they are more vulnerable to injury. Common stretches for knee problems include:
- Hamstring stretches for the back of the thighs
- Quadriceps stretches for the front of the thighs
Check with your doctor or physical therapist about exercises and stretches that are safe for you.
Home remedies for knee pain
Home remedies are often effective for fixing minor knee pain. Self-care treatment includes:
- Rest: When knee pain happens with a specific activity, take a break from it. Allow time for healing before resuming it.
- Ice: Applying an ice pack to your knee for 20 minutes intervals can relieve pain and inflammation. Repeat this several times a day.
- Elevation: You can help reduce swelling by propping your knee up while you are sitting.
- Heat: For some people, heat is more comforting and effective at relieving minor knee pain.
- Over-the-counter pain relievers: NSAIDs target pain and swelling from minor injuries. Acetaminophen (Tylenol) may help with pain if you can’t take NSAIDs, but it won’t help inflammation.
Alternative treatments for knee pain
Glucosamine and chondroitin is a popular supplement for joint pain, especially OA pain. Studies have mixed results about whether or not the combination really works. But it may be worth a try. Discuss it with your doctor before starting to make sure there isn’t a reason for you to avoid it.
What are the potential complications of knee pain?
Complications of knee pain can vary depending on the underlying cause. Pain due to a minor condition, such as a mild muscle strain or bruise, usually responds to rest, ice, and over-the-counter anti-inflammatory medications. However, some underlying causes of knee pain, such as a joint infection or deep vein thrombosis, can lead to serious and possibly life-threatening complications including:
- Adverse effect of treatment
- Loss of hip or knee joint mobility
- Permanent joint instability
- Permanent loss of sensation
- Permanent nerve damage
- Poor quality of life
- Pulmonary embolism associated with deep vein thrombosis
- Spread of infection and serious infections such as gangrene
- Weakness or paralysis
It is important to contact your healthcare provider when you have persistent pain or other unusual symptoms involving your knee. Once you diagnose the underlying cause, following the treatment plan outlined by your healthcare provider can lower your risk of complications.