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Symptoms and Signs of Knee Pain

Doctor's Notes on Knee Pain

Knee pain is any type of pain (sharp, dull, aching, recurrent, for example) that occurs in the knee either at rest or during use. There are two main types, acute and chronic. Signs and symptoms of acute knee pain include sharp and intense pain; the knee cannot support weight and the patient usually can’t walk. In addition, the knee can swell and be very tender to touch. If ligaments are torn, the person may hear a popping sound. If tendons are involved, the patient may not be able to extend the knee while meniscal injuries may cause the knee to lock. Dislocation of the knee result in limb – threatening emergencies where the knee looks out of place and the patient has severe pain. A dislocated kneecap is visibly out of place, painful, and the patient may not be able to flex or extend the knee. Chronic knee pain has many causes; signs and symptoms include knee pain that occurs more often with activity, the knee may be stiff; some patients may have swelling and pain in other joints. Other symptoms and signs depend on the underlying cause of chronic knee pain and include painful, swelling and warm to the touch knee joints – they also may be unable to have full range of knee motion. Infection of the knee joint can produce symptoms of fever, chills, knee swelling and joint warmth. Other less frequent causes usually result in intermittent pain in the joint and/or tendons that worsen when the knee joint is moved.

There are many causes of acute and chronic knee pain. Causes of acute knee pain include trauma, fractures, strained and/or torn collateral and cruciate ligaments, tendon ruptures, meniscal injuries, knee dislocation and kneecap dislocation. Causes of chronic knee pain include osteoarthritis, rheumatoid arthritis, gout, bursitis, infection, chondromalacia patella (mistracking by the kneecap), tendinitis (jumpers’ knee), Osgood – Schlatter disease (quadriceps tendon inflammation) and iliotibial band syndrome (lateral knee pain due to ligament stress).

Medical Author:
Medically Reviewed on 3/11/2019

Knee Pain Causes

The nerves that provide sensation to the knee come from the lower back and also provide hip, leg, and ankle sensation. Pain from a deeper injury (called referred pain) can be passed along the nerve to be felt on the surface. Knee pain, therefore, can arise from the knee itself or be referred from conditions of the hip, ankle, or lower back. All of the following sources of knee pain arise from the knee joint itself.

In general, knee pain is either immediate (acute) or long-term (chronic). Acute knee pains can be caused by an acute injury or infection. Chronic knee pains are often from injuries or inflammation (such as arthritis) but can also be caused by infection.

Acute knee pain

  • Fractures (broken bones)
    • Description: Fractures of any of the bones of the knee are traumatic injuries typically caused by moderate to high forces (such as car accidents or contact sports).
    • Symptoms and signs: Fractures may be accompanied by swelling or bruising but are almost always extremely painful and tender. The pain is typically so severe that people are unable to walk or even put weight on the knee.
    • Evaluation: Fractures are an emergency and should be checked by a doctor. This evaluation will generally include an X-ray and other relevant studies. A delay in evaluation can result in fracture fragments being moved and associated injuries.
    • Treatment: Depending on the particular fracture, the doctor may either recommend immobilization (with a cast or splint) or surgery to repair it.
    • Prognosis: Fractures often heal with no long-term problems. Some fractures, however, are complicated by arthritis or by injuries to arteries or nerves that can be serious.
  • Sprained and torn collateral ligaments
    • Description: The medial collateral ligament (MCL) is the most commonly injured ligament in the knee. Like all ligaments, this ligament may be sprained or torn. A sprained ligament may be partially ruptured. A torn ligament is completely ruptured.
    • Symptoms and signs: Severe MCL sprains or tears often produce a tearing or ripping sensation along the inner joint line of the knee. You may also notice knee instability and swelling. A force from the outer (lateral) knee to the inner (medial) knee is typically responsible for this injury in contrast to the more rarely injured LCL, which is typically a result of an inner to outer force. In general, bruises occur at the point of impact. Sprained and torn ligaments occur opposite the point of impact. Both MCL and LCL injuries are common in contact sports but can also result from twisting the knee with a planted foot such as in skiing. Injured medial and lateral collateral ligaments are typically tender at the inner and outer knee respectively.
    • Evaluation: After a history and physical examination, conservative treatment with rest, application of cold packs, and elevation of the involved extremity is often recommended. With persisting symptoms, the doctor may suggest an MRI scan or arthroscopy to further evaluate an injured ligament.
    • Treatment: For a mild sprain, early rehabilitation with compression, ice, elevation, anti-inflammatories, and pain-control medications along with an exercise regimen including a stationary bike and leg-strengthening exercises may be all you need. Such an exercise regimen should be under the supervision of a doctor or physical therapist because certain exercises are to be avoided. In contrast to sprains, tears often require surgical repair for best results.
    • Prognosis: The long-term outlook for ligament injury depends on the severity of the injury and the recovery from any surgical repair.
  • Sprained and torn cruciate ligaments
    • Description: An anterior cruciate ligament (ACL) injury is a common sports injury generally caused by a hard stop or a violent twisting of the knee. The posterior cruciate ligament (PCL) is stronger than the ACL and much less commonly torn. The PCL requires strong forces, such as those produced when the dashboard strikes the knee in a car accident, to tear. Due to these severe forces, PCL injury is often associated with other ligament and bone injuries.
    • Symptoms and signs: If you tear your ACL, you may hear a pop. You will also notice your knee give way or become unstable and feel pain.. This will, almost always, be followed by marked knee swelling over the next couple of hours because the ACL bleeds briskly when torn.
    • Treatment: Surgical repair is recommended for athletes who require return to competition. Conservative treatment and knee braces may prove sufficient for those who do not demand quite so much from their knees.
  • Tendon ruptures
    • Description: Both the quadriceps and patellar tendons may rupture partially or completely. Quadriceps tendon rupture typically occurs in recreational athletes older than 40 years (this is the injury President Clinton suffered while jogging), and patellar tendon rupture typically occurs in younger people who have had previous tendonitis or steroid injections to the knee.
    • Symptoms and signs: Rupture of either the quadriceps or patellar tendon causes pain (especially when trying to kick or extend the knee). Those people with complete ruptures are unable to extend the knee. The patella is also often out of place either upward (with patellar tendon rupture) or downward (with quadriceps tendon rupture). The patient can usually notice a difference in appearance when comparing his/her knees.
    • Treatment: Tendon ruptures should be evaluated urgently. Tendon ruptures generally require surgical repair. A partial rupture may be treated with splinting alone.
  • Meniscal injuries
    • Description: Injuries to the meniscus are typically traumatic injuries but can also be due to overuse. Often, a piece of the meniscus will tear off and float in the knee joint.
    • Symptoms and signs: Meniscal injuries may cause the knee to lock in a particular position or either click or grind through its range of motion. Meniscal injuries may also cause the knee to give way. Swelling typically accompanies these symptoms although the swelling is much less severe than with an ACL injury.
    • Treatment: Meniscal injuries often require arthroscopic surgical repair. A locking knee or a knee that "gives" should be evaluated for arthroscopic repair.
  • Knee dislocation
    • Description: Dislocation of the knee is a true limb-threatening emergency. This is also a rare injury. Dislocation of the knee is caused by a particularly powerful blow to the knee. The lower leg becomes completely displaced with relation to the upper leg. This displacement stretches and frequently tears not only the ligaments of the knee but also arteries and nerves. Untreated arterial injuries leave the lower leg without a blood supply. In this case, amputation may be required. Nerve injuries, on the other hand, may leave the lower leg viable but without strength or sensation.
    • This injury can be due to a motor vehicle accident where the patient's knee or leg hits the dashboard.
    • Symptoms and signs: Knee dislocations are severely painful and produce an obvious deformity of the knee. Many dislocations are reduced or put back into anatomic alignment spontaneously. As this occurs, many will report feeling a dull clunk.
    • Treatment: If the knee dislocation has not been put back into place (reduced), the doctor will immediately reduce the dislocation. Medical treatment, however, does not stop here. Whether a dislocation reduces by itself or is put back into place in the hospital, it requires further evaluation and care. After reduction, people with these injuries are observed in the hospital, where they usually do a number of tests to ensure that no arterial or nerve injury has occurred. If such an injury is found, it must be repaired immediately in the operating room.
  • Dislocated kneecap (patella)
    • Description: A common injury caused by direct trauma or forceful straightening of the leg, such as an injury that happens when serving in volleyball or tennis. Patellar dislocation is more common in women, the obese, knock-kneed people, and in those with high-riding kneecaps.
    • Symptoms and signs: If you have this injury, you will notice the patella being out of place and may have difficulty flexing or extending your knee.
    • Treatment: The doctor will pop the patella back into place (reduce the dislocation). Even if the patella goes back into place by itself, however, it needs to be X-rayed for a fracture. After reducing the patella and ensuring the absence of a fracture, the doctors will treat these injuries by splinting the knee for three weeks to allow the soft tissues around the patella to heal followed by strengthening exercises to keep the patella in line.
  • Arthritis: Arthritis of the knee is an inflammatory disorder of the knee joint that is often painful. Arthritis has many causes.
    • Osteoarthritis
      • Description: Osteoarthritis is caused by degeneration of cartilage in the knee. In its extreme form, the menisci (cartilage) will be completely eroded, and the femur will rub on the tibia, bone on bone.
      • Symptoms and signs: Osteoarthritis (OA) causes a chronically painful knee that is often more painful with activity. It can be stiff with prolonged sitting and may become enlarged from new bone formation at the edge of the degenerated cartilage.
      • Treatment: Treatment is aimed at pain control with over-the-counter pain relievers. Anti-inflammatory medications, either over the counter, or by your doctor's prescription, are also quite helpful. Knee bracing can be beneficial for more mobile patients. Injections of hyaluronic acid (viscosupplementation; Synvisc-One) can be helpful in relieving chronic pain from OA. More severe OA can be treated with narcotic pain medicines or a knee joint replacement with a synthetic joint.
    • Rheumatoid arthritis
      • Description: Rheumatoid arthritis (RA) is a disease of the whole body that affects many joints, often including the knee. People who have this disease often have family members who suffer from it as well.
      • Symptoms and signs: In addition to knee pain, rheumatoid arthritis may produce morning stiffness and pain in other joints. The knee can be warm to the touch and swollen.
      • Treatment: Treatment includes pain medications, anti-inflammatory medications, and prescription drugs. (These drugs either try to slow the progression of the disease or try to suppress the immune system or decrease inflammation.) Newer medications, called biologics, are proteins that specifically target the substances that stimulation rheumatoid inflammation. Your health care professional will need to evaluate which one of these medications is best suited for you.
      • Prognosis: It is essential that patients with rheumatoid arthritis be evaluated and treated aggressively early for best outcomes. This generally will include a thorough evaluation by a rheumatologist.
    • Crystalline arthritis (gout and pseudogout)
      • Description: These severely painful forms of arthritis are caused by crystals that form in the knee and other joints. These crystals can form as a result of defects in the absorption or metabolism of various natural substances such as uric acid (which produces gout) and calcium pyrophosphate (pseudogout).
      • Symptoms and signs: Gout and pseudogout cause a rapid-onset, markedly inflamed knee joint. The knee can be exquisitely painful, swollen, and warm with loss of range of motion.
      • Treatment: Treatment is aimed at controlling inflammation with anti-inflammatory medications and at aiding the metabolism of the various chemicals that may lead to crystal formation. Alcohol should be avoided and gout-specific dietary changes can be successful in avoiding flare-ups.
  • Bursitis
    • Description: As a result of trauma, infection, or crystalline deposits, the various bursae of the knee may become inflamed.
    • Symptoms and signs: Acute or chronic trauma causes a painful and often swollen knee from the inflammation of the bursae. A particularly common bursitis is prepatellar bursitis. This type of bursitis occurs in people who work on their knees. It is often referred to as housemaid's knee or carpet layer's knee. Another type of bursitis is anserine bursitis. The anserine bursa is located about 2 inches below the knee along the medial side of the knee. Though it occurs more commonly in the overweight and in women, it also affects athletes and others. Anserine bursitis often causes pain in the region of the bursa and is often worse with bending the knee or at night with sleep.
    • Treatment: Treatment will usually include home care with PRICE therapy and NSAIDs. Severe forms, however, can be treated with periodic steroid injections to the bursae.
    • Prognosis: With optimal treatment and management, patients generally do very well.
  • Infection (or infectious arthritis)
    • Description: Many organisms can infect the knee. Gonorrhea, a common sexually transmitted disease, can infect the knee, as can common organisms residing on normal skin, especially when the immune system is suppressed by underlying diseases or certain medications.
    • Symptoms and signs: Infection of the knee causes painful knee swelling. In addition, people who develop such an infection typically complain of fevers and chills. Less severe infections may not have associated fevers.
    • Treatment: New swelling and pain in the knee must be evaluated for infection based on your doctor's opinion. Treatment usually includes intensive antibiotic therapy and may include aspiration of the joint or surgical drainage of the infection.
    • Prognosis: The outlook depends on how early the appropriate antibiotic therapy is begun. Infection in a knee joint can lead to permanent cartilage damage.
  • Patellofemoral syndrome and chondromalacia patella
    • Description: These two conditions represent a spectrum of disease caused by patellar mistracking.
    • Symptoms and signs: The condition typically occurs in young women and also in athletes of both sexes and elderly people. In patellofemoral syndrome, the patella rubs against the inner or outer femur rather than tracking straight down the middle. As a result, the patellofemoral joint on either the inner or outer side may become inflamed, causing pain that is worse with activity or prolonged sitting. As the condition progresses, softening and decay of the articular cartilage on the underside of the patella occurs, and the syndrome is referred to as chondromalacia patella.
    • Treatment: Home care with PRICE therapy, NSAIDs, and exercises (such as straight leg raises) that balance the muscles around the patella work for most people. Others may benefit from commercial arch supports (for the arch of the foot) or orthotic supports that correct foot mechanics and may reduce abnormal forces on the knee. Severe cases of patellofemoral syndrome or chondromalacia may be treated surgically through a variety of procedures.
  • Jumper's knee
    • Description: Tendonitis (inflammation of the tendon) of the quadriceps tendon at the upper point of the patella, where it inserts, or tendonitis of the patellar tendon either at the lower point of the patella, or at the place where it inserts on the tibia (called the tibial tuberosity, about 2 inches below the knee on the front side), is termed jumper's knee. Jumper's knee is so named because it is typically seen in basketball players, volleyball players, and people doing other jumping sports.
    • Symptoms and signs: Jumper's knee causes localized pain that is worse with activity. It usually hurts more as you jump up than when you land because jumping puts more stress on tendons of the knee.
    • Treatment: Home therapy with the PRICE regimen together with anti-inflammatory drugs is the basis of treatment. Particularly important are rest, ice, and NSAID drugs, which will help stop the pain and break the cycle of inflammation. After controlling the pain, you should slowly start an exercise regimen to strengthen the quadriceps and hamstring muscles and resume your sport of choice a few weeks down the line.
  • Osgood-Schlatter disease
    • Description: Osgood-Schlatter disease occurs most commonly in adolescents participating in sports where repetitive extension of the knee causes inflammation and injury of the tibial tubercle (of the bone itself). It can occur in nonathletes as well and is usually linked to growth spurts during puberty.
    • Symptoms and signs: Children suffering from this syndrome report pain at the tibial tubercle (the tibial tubercle is the protuberant knob on the front of the tibia, a couple of inches below the knee, where the patellar tendon attaches). This pain is typically worse when extending the leg. The tibial tubercle is tender to touch and over time begins to protrude more because the chronic inflammation stimulates the bone to grow.
    • Treatment: Osgood-Schlatter disease is a self-limited condition that usually resolves as the bone stops growing with the end of adolescence (at about 17 years of age in males and 15 years of age in females). Treatment includes PRICE and NSAID therapy. In severe cases, splinting the knee for a few weeks may help reduce the pain and halt the inflammation cycle.
  • Iliotibial band syndrome
    • Description: A fibrous ligament, called the iliotibial band, extends from the outside of the pelvic bone to the outside of the tibia. When this band is tight, it may rub against the bottom outer portion of the femur (the lateral femoral epicondyle).
    • Symptoms and signs: Distance runners typically suffer from this condition. These runners complain of outside knee pain usually at the lateral femoral epicondyle. Early on, the pain will typically come on 10-15 minutes into a run and improve with rest.
    • Treatment: The most important aspect of treating iliotibial band syndrome is to stretch the iliotibial band. One way to do this is to place the right leg behind the left while standing with your left side about 2-3 feet from a wall. Then, lean toward your left for 20-30 seconds using the wall to help you support yourself. In addition to stretching the iliotibial band, PRICE therapy and NSAIDs may be of some help.

Pain Management Knee Pain Dos and Don'ts Slideshow

Pain Management Knee Pain Dos and Don'ts Slideshow

Take a break so your knee has time to heal. You'll only need 1 or 2 days of rest to ease minor knee pain, but severe injuries may keep you off your feet longer. Talk to your doctor if it doesn't get better after a few days.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.