Knee Pain: Symptoms, Causes, Diagnosis, and Treatment Guide

Oct 10

15 min read

Updated: 3 days ago

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Quick Answer

Knee pain is discomfort that can come from injuries like ACL tears, fractures, torn meniscus or bursitis, mechanical problems or arthritis, including osteoarthritis and gout. It may cause swelling, warmth, instability or popping. Most minor cases respond to rest, ice, compression, elevation and OTC pain relievers. See a doctor immediately if you cannot bear weight or have fever with swelling.

What the research says

Exercise therapy reduced knee osteoarthritis pain and improved function. A Cochrane review of 54 randomized trials found that land-based exercise reduced knee pain by about 12 points on a 0-100 scale (44 trials, 3,537 participants) and improved physical function by about 10 points right after treatment, with smaller benefits still present 2 to 6 months later (Fransen et al., Cochrane Database of Systematic Reviews, 2015 [2]).
Arthroscopic surgery added little for degenerative knee disease. A systematic review of 13 randomized trials and 12 observational studies found that, compared with conservative management, knee arthroscopy reduced pain by only 5.4 points on a 100-point scale up to 3 months and by 3.1 points (very small or no benefit) up to 2 years (Brignardello-Petersen et al., BMJ Open, 2017 [3]).

What Is Knee Pain?

Knee anatomy diagram labeling the kneecap (patella), bursae, ACL, meniscus and patellar tendon, with common pain zones and the likely source of each. – rinnit.com — Figure 1: Knee anatomy and the common sources of knee pain.

Knee pain is a common complaint that affects people of all ages. It may result from an injury, such as a ruptured ligament or torn cartilage. Medical conditions — including arthritis, gout, and infections — also can cause knee pain.

The location and severity of knee pain vary depending on the cause. Your knee may hurt when you walk, bend it, or rest it. Sometimes the pain fades with self-care. Sometimes it needs medical treatment.

Many types of minor knee pain respond well to self-care measures. Physical therapy and knee braces also can help relieve pain. In some cases, however, your knee may require surgical repair.

What are the symptoms of knee pain?

Knee pain symptoms vary from person to person and depend on what is causing the problem. The signs that often accompany knee pain include:

Symptom	What You Notice
Swelling and stiffness	The knee looks puffy and feels hard to bend
Redness and warmth	The skin over the knee looks red and feels hot
Weakness or instability	The knee feels weak or gives out
Popping or crunching noises	You hear or feel sounds when the knee moves
Trouble straightening	You cannot fully straighten the knee

When should you see a doctor about knee pain?

Call your healthcare professional if you cannot bear weight on your knee or feel as if your knee is unstable or gives out. Also seek care if you have marked knee swelling, or you are unable to fully extend or flex your knee.

See a doctor right away if you notice an obvious deformity in your leg or knee, or if you have a fever along with redness, pain, and swelling. Severe knee pain linked to an injury also needs prompt evaluation.

Warning Sign	What It May Mean
Cannot bear weight	Possible significant injury or instability
Marked swelling	Fluid buildup needing evaluation
Cannot fully bend or straighten	Joint mechanics may be affected
Obvious deformity	Possible dislocation or fracture
Fever with redness, pain, swelling	Possible joint infection needing urgent care

What Causes Knee Pain?

Infographic of the four categories of knee pain causes — injuries, mechanical problems, arthritis, and other — with examples listed under each. – rinnit.com — Figure 2: The four categories of knee pain causes.

Knee pain can be caused by injuries, mechanical problems, types of arthritis, and other problems. The knee joint involves ligaments, tendons, fluid-filled sacs (bursae), bones, and cartilage — and any of these structures can cause pain.

Knee Injuries

An injury can affect any of the ligaments, tendons, or bursae that surround your knee joint, as well as the bones, cartilage, and ligaments that form the joint itself.

An ACL injury is a tear of the anterior cruciate ligament — one of four ligaments that connect your shinbone to your thighbone. The ACL connects the thigh bone (femur) to the shinbone (tibia) and helps stabilize the knee. ACL tears happen most commonly during sports with sudden stops, jumps, pivots, or changes in direction. It is particularly common in people who play basketball, soccer, or similar sports.

Fractures are breaks in the bones of the knee, including the kneecap (patella). They can happen during falls or auto accidents. People with bones weakened by osteoporosis can sometimes fracture a knee simply by stepping wrong.

A torn meniscus involves the meniscus — the C-shaped piece of tough, rubbery cartilage that acts as a shock absorber between the shinbone and the thighbone. It can tear if you suddenly twist your knee while bearing weight on it.

Knee bursitis is inflammation in the bursae — the small sacs of fluid that cushion the outside of your knee joint so that tendons and ligaments glide smoothly over the joint.

Patellar tendinitis is irritation and inflammation of one or more tendons — the thick, fibrous tissues that attach muscles to bones. It happens when the patellar tendon (which runs from the kneecap to the shinbone and allows you to kick, run, and jump) becomes inflamed. Runners, skiers, cyclists, and people in jumping sports may develop it.

Injury	What It Is	Who Gets It
ACL tear	Tear of the ligament connecting shinbone to thighbone	Basketball, soccer, pivot sports
Fracture	Broken knee bones, including the kneecap	Falls, accidents, osteoporosis
Torn meniscus	Tear in the shock-absorbing cartilage	Sudden twist while bearing weight
Knee bursitis	Inflammation of the cushioning fluid sacs	Joint stress or friction
Patellar tendinitis	Inflammation of the tendon from kneecap to shinbone	Runners, skiers, cyclists, jumpers

Mechanical Problems

A loose body forms when injury or degeneration of bone or cartilage causes a piece to break off and float in the joint space. This may not create problems unless the loose body interferes with knee joint movement — then the effect is something like a pencil caught in a door hinge.

Iliotibial band syndrome occurs when the tough band of tissue extending from the outside of your hip to the outside of your knee (the iliotibial band) becomes so tight that it rubs against the outer portion of your thighbone. Distance runners and cyclists are especially susceptible.

A dislocated kneecap occurs when the triangular bone covering the front of your knee (the patella) slips out of place, usually to the outside of your knee. In some cases, the kneecap stays displaced and you can see the dislocation.

Hip or foot pain can also cause knee pain. If you have hip or foot pain, you may change the way you walk to spare your painful joint. But this altered gait can place more stress on your knee joint.

Types of Arthritis

More than 100 different types of arthritis exist. The varieties most likely to affect the knee are summarized below.

Arthritis Type	What Happens
Osteoarthritis	Wear-and-tear condition; knee cartilage deteriorates with use and age; most common type
Rheumatoid arthritis	Autoimmune condition affecting almost any joint, including knees; severity varies, may come and go
Gout	Uric acid crystals build up in the joint; usually big toe but can occur in the knee
Pseudogout	Calcium-containing crystals form in joint fluid; knees are the most common joint affected
Septic arthritis	Infected knee joint causing swelling, pain, and redness, often with fever and no trauma; can quickly damage knee cartilage

Septic arthritis deserves special attention. It often occurs with a fever, and there is usually no trauma before the pain starts. It can quickly cause extensive damage to the knee cartilage. If you have knee pain with any of these symptoms, see your doctor right away.

What are the risk factors for knee pain?

Excess weight, lack of muscle flexibility or strength, and certain sports or occupations are factors that can raise your risk of knee pain and knee problems.

Excess weight. Being overweight or obese increases stress on your knee joints, even during ordinary activities such as walking or going up and down stairs. It also raises your risk of osteoarthritis by accelerating the breakdown of joint cartilage.

Lack of muscle flexibility or strength. A lack of strength and flexibility increases the risk of knee injuries. Strong muscles stabilize and protect your joints, and muscle flexibility helps you achieve full range of motion.

Certain sports or occupations. Some sports put greater stress on your knees than others. Alpine skiing with its rigid ski boots and potential for falls, basketball's jumps and pivots, and the repeated pounding from running or jogging all increase injury risk. Jobs that require repetitive stress on the knees, such as construction or farming, also increase your risk.

Previous injury. Having a previous knee injury makes it more likely that you will injure your knee again.

Risk Factor	How It Affects Your Knees
Excess weight	Adds stress during walking and stairs; accelerates cartilage breakdown
Weak or inflexible muscles	Less stability and protection for the joint
Skiing, basketball, running	Jumps, pivots, falls, and repeated pounding
Construction or farming jobs	Repetitive knee stress day after day
Prior knee injury	Higher chance of injuring the knee again

What are the complications of knee pain?

Not all knee pain is serious. But some knee injuries and medical conditions, such as osteoarthritis, can lead to increasing pain, joint damage, and disability if left untreated. And having a knee injury — even a minor one — makes it more likely that you will have similar injuries in the future.

How can knee pain be prevented?

Although it is not always possible to prevent knee pain, several steps may help ward off injuries and joint deterioration.

Keep extra pounds off. Maintaining a healthy weight is one of the best things you can do for your knees. Every extra pound puts additional strain on the joints, increasing the risk of injuries and osteoarthritis.

Be in shape to play your sport. Take time for conditioning to prepare your muscles for the demands of sports participation.

Practice perfectly. Make sure your technique and movement patterns are the best they can be. Lessons from a professional can be very helpful.

Get strong, stay flexible. Weak muscles are a leading cause of knee injuries. Build up your quadriceps and hamstrings — the muscles on the front and back of your thighs that support your knees. Balance and stability training helps the muscles around your knees work together more effectively. Tight muscles also contribute to injury, so stretching matters. Include flexibility exercises in your workouts.

Be smart about exercise. If you have osteoarthritis, chronic knee pain, or recurring injuries, consider changing the way you exercise. Swimming, water aerobics, or other low-impact activities at least a few days a week may help. Sometimes simply limiting high-impact activities provides relief.

Prevention Step	How It Helps
Maintain a healthy weight	Reduces strain on joints, lowers osteoarthritis risk
Condition for your sport	Prepares muscles for sport demands
Perfect technique	Reduces harmful movement patterns
Strengthen quadriceps and hamstrings	Supports and stabilizes the knee
Stretch regularly	Prevents tight muscles that contribute to injury
Choose low-impact exercise	Limits pounding on the joints

How is knee pain diagnosed?

During the physical exam, your healthcare professional is likely to inspect your knee for swelling, pain, tenderness, warmth, and visible bruising. They will check how far you can move your lower leg in different directions, and push on or pull the joint to evaluate the integrity of the structures in your knee.

Imaging Tests

In some cases, your healthcare professional might suggest imaging tests.

Test	What It Shows
X-ray	First test; detects bone fractures and degenerative joint disease
CT scan	Cross-sectional images from many X-ray angles; finds bone problems and subtle fractures; a special CT can accurately identify gout even when the joint is not inflamed
Ultrasound	Real-time sound-wave images of soft tissue; the knee may be moved into different positions during the exam
MRI	3D images from radio waves and a magnet; especially useful for ligament, tendon, cartilage, and muscle injuries

Lab Tests

If your healthcare professional suspects an infection or inflammation, you are likely to have blood tests. Sometimes a procedure called arthrocentesis is used, in which a small amount of fluid is removed from within your knee joint with a needle and sent to a laboratory for analysis.

What are the treatment options for knee pain?

Treatments will vary depending upon what exactly is causing your knee pain.

Medications

Your healthcare professional may prescribe medications to help relieve pain and to treat the conditions causing your knee pain, such as rheumatoid arthritis or gout.

Therapy

Strengthening the muscles around your knee will make it more stable. Your healthcare professional may recommend physical therapy or different types of strengthening exercises based on the specific condition causing your pain.

If you are physically active or play a sport, you may need exercises to correct movement patterns affecting your knees and to establish good technique during your sport or activity. Exercises to improve flexibility and balance also are important.

Arch supports, sometimes with wedges on one side of the heel, can help shift pressure away from the side of the knee most affected by osteoarthritis. In certain conditions, different types of braces may be used to help protect and support the knee joint.

Injections

In some cases, your healthcare professional may suggest injecting medications or other substances directly into your joint.

Injection	How It Works	What to Expect
Corticosteroids	May reduce arthritis flare symptoms and relieve pain	Relief may last a few months; not effective in all cases
Hyaluronic acid	Thick fluid similar to natural joint lubricant; improves mobility and eases pain	Relief may last as long as six months; study results are mixed
Platelet-rich plasma (PRP)	Concentrated growth factors that appear to reduce inflammation and promote healing	May benefit certain people with osteoarthritis; more studies needed

Surgery

If you have an injury that may require surgery, the operation is usually not necessary immediately. Before making a decision, consider the pros and cons of both nonsurgical rehabilitation and surgical reconstruction in relation to what is most important to you. Your surgical options may include:

Procedure	What It Does
Arthroscopic surgery	Fiber-optic camera and narrow tools through small incisions; removes loose bodies, repairs damaged cartilage, reconstructs torn ligaments
Partial knee replacement	Replaces only the most damaged portion with metal and plastic parts; smaller incisions and quicker healing
Total knee replacement	Removes damaged bone and cartilage from thighbone, shinbone, and kneecap; artificial joint of metal alloys, plastics, and polymers
Osteotomy	Removes bone from thighbone or shinbone to align the knee better; may delay or avoid total knee replacement

What lifestyle changes and home remedies help knee pain?

Infographic of six knee pain home care steps: rest, ice, heat, compression, elevation, and over-the-counter pain relievers. – rinnit.com — Figure 3: Six home care steps for knee pain.

Over-the-counter medications — such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) — may help ease knee pain. Some people find relief by rubbing the affected knee with creams containing a numbing agent, such as lidocaine, or capsaicin, the substance that makes chili peppers hot.

Self-care measures for an injured knee include:

Rest. Take a break from your normal activities to reduce repetitive strain on your knee, give the injury time to heal, and help prevent further damage. A day or two of rest may be all you need for a minor injury. More severe damage is likely to need a longer recovery time.

Ice. Ice reduces both pain and inflammation. A bag of frozen peas works well because it covers your whole knee. You also can use an ice pack wrapped in a thin towel to protect your skin. Although ice therapy is generally safe and effective, do not use ice for longer than 20 minutes at a time because of the risk of damage to your nerves and skin.

Heat. You may experience temporary pain relief by applying a heat pack or hot-water bottle to the painful area on your knee.

Compression. This helps prevent fluid buildup in damaged tissues and maintains knee alignment and stability. Look for a compression bandage that is lightweight, breathable, and self-adhesive. It should be tight enough to support your knee without interfering with circulation.

Elevation. To help reduce swelling, try propping your injured leg on pillows or sitting in a recliner.

Home Care Step	How to Do It
Rest	Pause normal activities; a day or two for minor injuries
Ice	Frozen peas bag or ice pack in a thin towel; max 20 minutes at a time
Heat	Heat pack or hot-water bottle for temporary relief
Compression	Lightweight, breathable bandage supporting without blocking circulation
Elevation	Prop the leg on pillows or use a recliner
OTC pain relievers	Ibuprofen or naproxen sodium may ease pain
Topical creams	Lidocaine or capsaicin creams rubbed on the knee

Can alternative medicine help with knee pain?

Research suggests that acupuncture may help relieve knee pain caused by osteoarthritis. Acupuncture involves the placement of hair-thin needles into your skin at specific places on your body.

How should you prepare for a knee pain appointment?

You are likely to start by seeing your family doctor. Depending on the cause of your problem, he or she may refer you to a doctor specializing in joint diseases (rheumatologist), joint surgery (orthopedic surgeon), or sports medicine.

What You Can Do

Before your appointment, you may want to write a list of answers to these questions: When did you begin experiencing symptoms? Did a specific injury make your knee start to hurt? Have your symptoms been continuous or occasional? How severe are your symptoms? What seems to improve or worsen your symptoms? What medications and supplements do you take regularly?

Taking a family member or friend along can help you remember the information given.

What Your Doctor May Ask

Your healthcare professional may ask some of these questions: Do you exercise or play sports? Was the pain caused by an injury? Do you experience any swelling, instability, or locking of the knee? Are you experiencing symptoms in other areas, or just in your knee? Have you ever had knee pain before, and if so, do you know what the cause was?

Conclusion

Knee pain affects people of all ages and can stem from injuries like ACL tears and torn meniscus, mechanical problems such as loose bodies or iliotibial band syndrome, or arthritis types including osteoarthritis, gout, and septic arthritis. Most minor cases improve with rest, ice, compression, elevation, and over-the-counter pain relievers, while persistent or severe cases may need physical therapy, injections, or surgery.

Ready to take the next step? If your knee hurts, swells, gives out, or you cannot bear weight on it — start with rest and ice, and see a healthcare professional if symptoms persist, worsen, or come with fever. Bring your symptom notes, medication list, and the questions in this guide to make the most of your visit.

Frequently Asked Questions

1. What is knee pain?

Knee pain is a common complaint affecting people of all ages, caused by injuries (like ruptured ligaments or torn cartilage), mechanical problems, or medical conditions such as arthritis, gout, and infections. Many minor cases respond well to self-care measures.

2. What are common knee pain symptoms?

Symptoms include swelling and stiffness, redness and warmth, weakness or instability, popping or crunching noises, and the inability to fully straighten the knee. Location and severity vary depending on the cause.

3. When should I see a doctor for knee pain?

Seek care if you cannot bear weight, have marked swelling, cannot fully bend or straighten the knee, notice an obvious deformity, have fever with redness and swelling, or have severe pain linked to an injury.

4. What causes knee pain?

Causes fall into four groups: injuries (ACL tears, fractures, torn meniscus, bursitis, patellar tendinitis), mechanical problems (loose body, iliotibial band syndrome, dislocated kneecap, altered gait from hip or foot pain), arthritis types, and other conditions like patellofemoral pain syndrome.

5. What is an ACL injury?

An ACL injury is a tear of the anterior cruciate ligament, one of four ligaments connecting your shinbone to your thighbone. It is common in sports with sudden stops, jumps, pivots, or direction changes, such as basketball and soccer.

6. What is a torn meniscus?

The meniscus is a C-shaped piece of tough, rubbery cartilage acting as a shock absorber between the shinbone and thighbone. It can tear if you suddenly twist your knee while bearing weight on it.

7. What is patellofemoral pain syndrome?

It is pain arising between the kneecap and the underlying thighbone. It is common in athletes, young adults whose kneecap does not track properly in its groove, and older adults with arthritis of the kneecap.

8. How is knee pain diagnosed?

Through a physical exam checking swelling, warmth, tenderness, range of motion, and joint integrity, plus imaging tests (X-ray, CT, ultrasound, MRI) and sometimes lab tests such as blood work or arthrocentesis, where joint fluid is drawn for analysis.

9. What are the best home remedies for knee pain?

Rest, ice (no longer than 20 minutes at a time), heat for temporary relief, compression, elevation, OTC pain relievers like ibuprofen or naproxen sodium, and topical creams with lidocaine or capsaicin.

10. What injections treat knee pain?

Corticosteroids (relief may last months), hyaluronic acid (similar to natural joint fluid; relief may last up to six months), and platelet-rich plasma (PRP), which may benefit certain people with osteoarthritis.

11. When is knee surgery needed?

When conservative treatments fail; options include arthroscopic surgery to remove loose bodies or repair cartilage and ligaments, partial or total knee replacement, and osteotomy to realign the knee and relieve arthritis pain.

12. How can I prevent knee pain?

Keep a healthy weight, condition for your sport, practice good technique, strengthen your quadriceps and hamstrings, stretch regularly, and switch to low-impact activities like swimming if you have chronic knee problems.

Sources

Mayo Clinic Staff. Knee pain - Symptoms and causes. Mayo Clinic. Jan. 25, 2023. https://www.mayoclinic.org/diseases-conditions/knee-pain/symptoms-causes/syc-20350849
Fransen M, McConnell S, Harmer AR, et al. Exercise for osteoarthritis of the knee. Cochrane Database of Systematic Reviews. 2015;1(1):CD004376. PMID 25569281. https://doi.org/10.1002/14651858.CD004376.pub3
Brignardello-Petersen R, Guyatt GH, Buchbinder R, et al. Knee arthroscopy versus conservative management in patients with degenerative knee disease: a systematic review. BMJ Open. 2017;7(5):e016114. PMID 28495819. https://doi.org/10.1136/bmjopen-2017-016114

Medical Disclaimer

This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.