Knee Problems and Injuries

Topic Overview

Most people have had a minor knee problem at one time or another. Most of the time our body movements do not cause problems, but it's not surprising that symptoms develop from everyday wear and tear, overuse, or injury. Knee problems and injuries most often occur during sports or recreational activities, work-related tasks, or home projects.

The knee is the largest joint in the body. The upper and lower bones of the knee are separated by two discs (menisci). The upper leg bone (femur) and the lower leg bones (tibia and fibula) are connected by ligaments, tendons, and muscles. The surface of the bones inside the knee joint is covered by articular cartilage, which absorbs shock and provides a smooth, gliding surface for joint movement. See an illustration of the structures of the knee.

Although a knee problem is often caused by an injury to one or more of these structures, it may have another cause. Some people are more likely to develop knee problems than others. Many jobs, sports and recreation activities, getting older, or having a disease such as osteoporosis or arthritis increase your chances of having problems with your knees.

Sudden (acute) injuries

Injuries are the most common cause of knee problems. Sudden (acute) injuries may be caused by a direct blow to the knee or from abnormal twisting, bending the knee, or falling on the knee. Pain, bruising, or swelling may be severe and develop within minutes of the injury. Nerves or blood vessels may be pinched or damaged during the injury. The knee or lower leg may feel numb, weak, or cold; tingle; or look pale or blue. Acute injuries include:

• Sprains, strains, or other injuries to the ligaments and tendons that connect and support the kneecap.
• A tear in the rubbery cushions of the knee joint (meniscus).
• Ligament tears. The medial collateral ligament (MCL) is the most commonly injured ligament of the knee.
• Breaks (fracture) of the kneecap, lower portion of the femur, or upper part of the tibia or fibula. Knee fractures are most commonly caused by abnormal force, such as a falling on the knee, a severe twisting motion, severe force that bends the knee, or when the knee forcefully hits an object.
• Kneecap dislocation. This type of dislocation occurs more frequently in 13- to 18-year-old girls. Pieces of bone or tissue (loose bodies) from a fracture or dislocation may get caught in the joint and interfere with movement.
• Knee joint dislocation. This is a rare injury that requires great force. It is a serious injury and requires immediate medical care.

Overuse injuries

Overuse injuries occur with repetitive activities or repeated or prolonged pressure on the knee. Activities such as stair climbing, bicycle riding, jogging, or jumping stress joints and other tissues and can lead to irritation and inflammation. Overuse injuries include:

• Inflammation of the small sacs of fluid that cushion and lubricate the knee (bursitis).
• Inflammation of the tendons (tendinitis) or small tears in the tendons (tendinosis).
• Thickening or folding of the knee ligaments (Plica syndrome).
• Pain in the front of the knee from overuse, injury, excess weight, or problems in the kneecap (patellofemoral pain syndrome).
• Irritation and inflammation of the band of fibrous tissue that runs down the outside of the thigh (iliotibial band syndrome).

Conditions that may cause knee problems

Problems not directly related to an injury or overuse may occur in or around the knee.

• Osteoarthritis (degenerative joint disease) may cause knee pain that is worse in the morning and improves during the day. It often develops at the site of a previous injury. Other types of arthritis, such as rheumatoid arthritis, gout, and lupus, also can cause knee pain, swelling, and stiffness.
• Osgood-Schlatter disease causes pain, swelling, and tenderness in the front of the knee below the kneecap. It is especially common in boys ages 11 to 15.
• A popliteal (or Baker's) cyst causes swelling in the back of the knee.
• Infection in the skin (cellulitis), joint (infectious arthritis), bone (osteomyelitis), or bursa (septic bursitis) can cause pain and decreased knee movement.
• A problem elsewhere in the body, such as a pinched nerve or a problem in the hip, can sometimes cause knee pain.
• Osteochondritis dissecans causes pain and decreased movement when a piece of bone or cartilage or both inside the knee joint loses blood supply and dies.

Treatment

Treatment for a knee problem or injury may include first aid measures, rest, bracing, physical therapy, medicine, and in some cases surgery. Treatment depends on the location, type, and severity of the injury as well as your age, health condition, and activity level (such as work, sports, or hobbies).

Review the Emergencies and Check Your Symptoms sections to determine if and when you need to see a doctor.

Emergencies

• Your knee joint-not your kneecap-has been pulled out of joint (dislocated).
• Signs of shock develop:
  • In children.
  • In adults and older children.
• Severe bleeding does not slow during the first 15 minutes of steady direct pressure.
• Your leg has been partially or completely amputated.
• After an acute (sudden) injury, there is an obvious broken bone with pieces of bone visible in a wound or a bone sticking through the skin. Note: Do not try to push the bone back into the skin. Cover the area with a clean bandage.

Check Your Symptoms

If you answer yes to any of the following questions, click on the "Yes" in front of the question for information about how soon to see a health professional.

Review health risks that may increase the seriousness of your symptoms.

If you have any of the following symptoms, evaluate those symptoms first.

• Calf or leg pain: Go to the topic Leg Problems, Noninjury.
• Leg injury: Go to the topic Leg Injuries.
• Bleeding: Go to the topic Cuts or Puncture Wounds.

	Yes	Do you think you have broken your knee or pulled your kneecap out of place? When to See a Doctor See significance of a fracture or dislocation if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Has your kneecap moved out of position (dislocated)? Yes Does your knee look twisted, bent out of shape, or out of its normal position after a recent injury? Yes Is your knee cut or scraped and you think you have broken or dislocated it? Call your health professional today if you answer "Yes" to the following question. Yes Did your knee pop, move, or get pulled out of its normal position and then return to its normal position? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you have knee pain or tenderness? When to See a Doctor See significance of knee pain or tenderness if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have severe pain? Yes Is a young child unable to walk or carefully protecting his or her knee after a known or suspected injury? Call your health professional today if you answer "Yes" to any of the following questions. Yes Do you have pain with swelling or bruising that began within 30 minutes of an injury? Yes Do you have moderate pain that is getting worse? You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions. Yes Do you have moderate pain that has not gotten better after 24 hours of home treatment? Yes Does moving or bending your knee still cause mild pain after 48 hours of home treatment? You need an appointment within the next 1 to 2 weeks if you answer "Yes" to the following question. Yes Have you had intermittent mild pain without other symptoms for 2 weeks? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Is your knee, lower leg, or foot pale, white, blue, or cold? When to See a Doctor See significance of pale, white, blue, or cold skin if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have knee pain and your lower leg or foot is pale, white, blue, or cold? Yes Did your lower leg or foot turn pale, white, blue, or cold after you had a splint or cast applied? Note: See first aid for a cast or splint that may be too tight. If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you have numbness or tingling in your knee, lower leg, or foot? When to See a Doctor See significance of numbness or tingling if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have knee pain with numbness or tingling in your knee, lower leg, or foot? Yes Have you had knee pain with steady numbness or tingling for 1 hour or longer? Yes Do you have new numbness or tingling, and the skin below your knee is pale, white, blue, or cold? Yes Are you unable to move your knee normally (not because of pain or because a splint is in the way)? Call your health professional today if you answer "Yes" to any of the following questions. Yes Is numbness or tingling getting worse? Yes Have you have steady numbness or tingling below your knee for 1 hour or longer, but you do not have other symptoms? You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to the following question. Yes Have you had numbness or tingling that comes and goes during the past 24 hours? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Has your knee given out, buckled, or felt unstable after an injury? When to See a Doctor See significance of a knee that buckles or feels unstable if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have severe pain? Yes Has a lot of swelling developed within 30 minutes of an injury? Yes Does your knee look twisted or bent out of its normal position? Yes Is your knee so unstable that you cannot stand or walk (bear weight)? Call your health professional today if you answer "Yes" to the following question. Yes Did your knee suddenly give out or buckle, but it seems all right now? You need an appointment within the next 1 to 2 weeks if you answer "Yes" to any of the following questions. Yes Has your knee felt unstable for a long time, but you have never had it checked by a doctor? Yes Has your knee felt unstable for a long time, and the problem has gotten worse since you had it checked by a doctor? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you have swelling of your knee? When to See a Doctor See significance of swelling if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to the following question. Yes Is the skin below the swollen area cold or pale? Call your health professional today if you answer "Yes" to the following question. Yes Has a lot of swelling or bruising developed within 30 minutes of an injury? You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions. Yes Have you had new swelling in the back of your knee for longer than 48 hours? Yes Do you have moderate swelling after 48 hours of home treatment? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Did you feel or hear a snap, pop, or grinding in your knee? When to See a Doctor See significance of a snap, pop, or grinding if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have severe pain? Yes Has a lot of swelling developed within 30 minutes of an injury? Yes Does your knee look twisted or bent out of its normal position? Yes Are you unable to stand or walk (bear weight)? Call your health professional today if you answer "Yes" to any of the following questions. Yes Did you feel or hear a snap, pop, or grinding, but you do not have other symptoms? Yes Did you feel or hear a snap or pop, and your knee has given out or feels like it will buckle? You need an appointment within the next 1 to 2 weeks if you answer "Yes" to the following question. Yes Have you had a grinding sensation in your knee, but you do not remember a specific injury? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you have knee weakness, stiffness, decreased movement, or locking? When to See a Doctor See significance of weakness, stiffness, decreased movement, or locking if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have severe pain? Yes Are you unable to straighten or bend your knee? Yes Are you unable to move your knee normally because of muscle weakness (not just because of pain)? Call your health professional today if you answer "Yes" to the following question. Yes Is a young child carefully protecting a knee or unable to walk after a known or suspected injury? You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to the following question. Yes Are you unable to move your knee normally or do you have decreased strength after 48 hours of home treatment? You need an appointment within the next 1 to 2 weeks if you answer "Yes" to the following question. Yes Does your knee lock from time to time, but it is not locked now? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you think that a knee injury may have been caused by abuse? When to See a Doctor See significance of abuse if you need information to help you answer the question below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to the following question. Yes Do you think that a knee injury may have been caused by abuse? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Do you think you have inflammation or infection in your knee? When to See a Doctor See significance of inflammation or infection in a joint if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional immediately if you answer "Yes" to any of the following questions. Yes Do you have increased swelling, redness, or warmth around your knee? Yes Do you have severe pain with movement of your knee? Yes Do you have red streaks extending from your knee? Yes Does it hurt to touch your knee? Yes Do you have drainage of pus from your knee? Yes Do you know or think you have a fever? Yes Do you have diabetes? Yes Do you have peripheral arterial disease? Yes Do you have a disease or take a medicine that causes problems with your immune system? You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions. Yes Have you had mild pain and swelling with redness less than 1 in. (2.5 cm) around the injured area for 24 hours? Yes Have you had swollen lymph nodes in the groin for longer than 48 hours? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
	Yes	Does your knee look bruised after an injury? When to See a Doctor See significance of bruising if you need information to help you answer the questions below. Review health risks that may increase the seriousness of your symptoms. Call your health professional today if you answer "Yes" to the following question. Yes Did a large (the size of the injured person's palm), painful, swollen bruise develop within 30 minutes of an injury? You need an appointment within the next 1 to 2 weeks if you answer "Yes" to any of the following questions. Yes Do you think you bruise too easily? Yes Have bruises from an injury lasted longer than 2 weeks? If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.

Other Symptoms to Watch For

Do you have any of the following symptoms?

• A burn, scrape, or bite: Go to the topic Burns, Scrapes, or Animal and Human Bites.

If a visit to a health professional is not needed immediately, see the Home Treatment section for self-care information.

Home Treatment

Home treatment may help relieve pain, swelling, and stiffness.

• Rest and protect an injured or sore area. Stop, change, or take a break from any activity that may be causing your pain or soreness. When resting, place a small pillow under your knee.
• Ice will reduce pain and swelling. Apply ice or cold packs immediately to prevent or minimize swelling. Apply the ice or cold pack for 10 to 20 minutes, 3 or more times a day.
  • For the first 48 hours after an injury, avoid things that might increase swelling, such as hot showers, hot tubs, hot packs, or alcoholic beverages.
  • After 48 to 72 hours, if swelling is gone, apply heat and begin gentle exercise with the aid of moist heat to help restore and maintain flexibility. Some experts recommend alternating between heat and cold treatments.
• Compression, or wrapping the injured or sore area with an elastic bandage (such as an Ace wrap), will help decrease swelling.
  • Don't wrap it too tightly, since this can cause more swelling below the affected area. Loosen the bandage if it gets too tight. Signs that the bandage is too tight include numbness, tingling, increased pain, coolness, or swelling in the area below the bandage.
  • Don't expect the bandage to protect or stabilize a knee injury.
  • Talk to your doctor if you think you need to use a wrap for longer than 48 to 72 hours; a more serious problem may be present.
• Elevate the injured or sore area on pillows while applying ice and anytime you are sitting or lying down. Try to keep the area at or above the level of your heart to help minimize swelling.
• Reduce stress on your sore knee (until you can get advice from your doctor):
  • Use a cane or crutch in the hand opposite your painful knee.
  • Use two crutches, keeping weight off the leg with the sore knee. You can get canes or crutches from most pharmacies. Crutches are recommended if a cane causes you to walk with a limp.
• Gently massage or rub the area to relieve pain and encourage blood flow. Do not massage the injured area if it causes pain.
• Try the following exercises to maintain flexibility:
  • Hamstring stretch
  • Knee-to-chest exercise
• Avoid high-impact exercise, such as running, skiing, snowboarding, or playing tennis, until your knee is no longer painful or swollen.

Do not smoke. Smoking slows healing because it decreases blood supply and delays tissue repair. For more information, see the topic Quitting Tobacco Use.

Symptoms to Watch For During Home Treatment

Use the Check Your Symptoms section to evaluate your symptoms if any of the following occur during home treatment:

• Signs of infection develop.
• Numbness, tingling, or weakness develops.
• Your knee, lower leg, or foot becomes pale or cool or looks blue.
• Symptoms do not improve with home treatment.
• Symptoms become more severe or frequent.

Prevention

The following tips may prevent knee problems.

General prevention tips

• Wear your seat belt in a motor vehicle.
• Don't carry objects that are too heavy. Use a step stool. Do not stand on chairs or other unsteady objects.
• Wear knee guards during sports or recreational activities, such as roller-skating or soccer.
• Stretch before and after physical exercise, sports, or recreational activities to warm up your muscles.
• Use the correct techniques or positions during activities so that you do not strain your muscles.
• Use equipment appropriate to your size, strength, and ability. Avoid repeated movements that can cause injury. In daily routines or hobbies, look at activities in which you make repeated knee movements.
• Consider taking lessons to learn the proper technique for sports. Have a trainer or person who is familiar with sports equipment check your equipment to see if it is well suited for your level of ability, body size, and body strength.
• If you feel that certain activities at your workplace are causing pain or soreness from overuse, call your human resources department for information on other ways of doing your job or to talk about using different equipment.

Tips specific to the knee

• Keep your knees and the muscles that support them strong and flexible. Warm up before activities. Try the following stretches:
  • Hamstring stretch
  • Knee-to-chest exercise
  • Calf stretch
  • Straight-leg raises
• Avoid activities that stress your knees, such as deep knee bends or downhill running.
• Wear shoes with good arch supports.
• Do not wear high-heeled shoes.
• When playing contact sports, wear the right shoes that are made for the surface you are playing or running on, such as a track or tennis court.
• Replace running shoes every 300 to 500 miles (480 to 800 kilometers).

Tips specific to female athletes

Sports trainers recommend training programs that help women learn to run, jump, and pivot with knees bent to avoid knee injuries. In sports such as soccer, basketball, and volleyball, women who bend their knees and play low to the ground have fewer knee injuries than women who run and pivot with stiff legs.

Knee brace use

Some people use knee braces to prevent knee injuries or after a knee injury. There are many types of knee braces, from soft fabric sleeves to rigid, metal hinged braces, that support and protect the knee. If your doctor has recommended the use of a knee brace, follow his or her instructions. If you are using a knee brace to help prevent problems, follow the manufacturer's instructions for use.

Keep bones strong

• Eat a nutritious diet with enough calcium and vitamin D, which helps your body absorb calcium. Calcium is found in dairy products, such as milk, cheese, and yogurt; dark green, leafy vegetables, such as broccoli; and other foods. For more information, see the topic Healthy Eating.
• Exercise and stay active. It is best to do weight-bearing exercise, such as walking, jogging, stair climbing, dancing, or lifting weights, for 45 to 60 minutes at least 4 days a week. Weight-bearing exercises stimulate new bone growth by working the muscles and bones against gravity. Exercises that are not weight-bearing, such as swimming, are good for your general health but do not stimulate new bone growth. Talk to your doctor about an exercise program that is right for you. Begin slowly, especially if you have been inactive. For more information, see the topic Fitness.
• Avoid drinking more than one alcoholic drink per day. People who drink more than this may be at higher risk for weakening bones (osteoporosis). Alcohol use also increases your risk of falling and breaking a bone.
• Stop or do not begin smoking. Smoking puts you at a much higher risk for developing osteoporosis. It also interferes with blood supply and healing. For more information, see the topic Quitting Tobacco Use.

Possible abuse

Bruises are often the first sign of abuse. Seek help if:

• You suspect abuse. Call your local child or adult protective agency, police, or a doctor, nurse, or counselor.
• You or someone you know is a victim of violence.
• You have trouble controlling your anger with a child or other person in your care. Resources are available for help.

Preparing For Your Appointment

To prepare for your appointment, see the topic Making the Most of Your Appointment

You can help your doctor diagnose and treat your condition by being prepared to answer the following questions:

• What are your main symptoms?
• How long have you had your symptoms?
• What were you doing when your symptoms started?
• Have you had this problem in the past?
  • What was the diagnosis?
  • How was it treated?
• How and when did an injury occur? How was it treated? Were illegal drugs or alcohol involved in your injury?
• Have you had any injuries in the past to the same area? Do you have any continuing problems because of the previous injury?
• Have you ever had knee surgery?
• What activities, related to sports, work, or your lifestyle, make your symptoms better or worse?
• Do you think that activities related to your job or hobbies caused your symptoms?
• What home treatment measures have you tried? Did they help?
• What nonprescription medicines have you taken? Did they help?
• Do you have any health risks?

Related Information

• Animal and Human Bites
• Anterior Cruciate Ligament (ACL) Injuries
• Bruises and Blood Spots Under the Skin
• Burns
• Bursitis
• Cuts
• Gout
• Lupus (Systemic Lupus Erythematosus)
• Osteoarthritis
• Puncture Wounds
• Rheumatoid Arthritis
• Scrapes
• Toe, Foot, and Ankle Injuries
• Toe, Foot, and Ankle Problems, Noninjury

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