Knee Pain
The knee joint is a joint composed of three bones: the femur (thigh bone), the tibia (shin bone) and the patella (knee cap). The ends of the three bones are covered with cartilage and cushioning called menisci. The cartilage and menisci are made of a tough, elastic material that helps absorb shock and allows the knee joint to move smoothly. Two groups of muscles, the quadriceps muscle in the front and the hamstring muscles along the back, allow the knee to move. The quadriceps tendon connects the quadriceps muscle to the patella. The medial collateral ligament (MCL), the lateral collateral ligament (LCL), and the anterior and posterior cruciate ligaments are some of the ligaments that connect the bones and provide stability. Any of these parts of the knee can be injured.
The knees are regularly under stress, not only from high-impact sports, but also from everyday activities such as squatting, stooping, kneeling and climbing stairs. The knees get bent, twisted and occasionally banged into during sports.
Causes
Knee joint: three-quarter view of front right knee
Medical conditions, such as arthritis, can cause knee pain. But the knee injuries that commonly occur in younger people involve a blow, a sudden twist or a hard landing after a jump. A single strong blow in just the right place can tear cartilage and sprain several ligaments.
Sprains
Sprains are the result of a blow or sudden twist of the knee. A sprain of the ligaments of the knee causes swelling (usually within an hour), pain and difficulty walking. The sprained side of the knee may be tender to the touch. Even mild knee sprains often take two or more weeks to fully heal. A strong blow to the inner or outer side of the knee will sprain either the MCL or the LCL (injuries to the MCL are more common). The ligament on the opposite side of the blow is forced to bend sideways. If you feel pain on the side where the blow occurred, it's probably a bruise and not a sprain. A sprained knee is a significant injury. All sprains should be seen by a doctor to avoid risk of an unstable knee later.
ACL injuries, Torn Cartilage (Menisci) and the "Terrible Triad"
ACL injuries, torn cartilage (menisci) and the "terrible triad" are the result of damage to the ligaments or menisci. The menisci are two disks of cartilage that attach to the cartilage of the knee and fit into the joint to absorb shock. The anterior cruciate ligament (ACL) can be stretched or torn. ACL injuries are common in contact sports or skiing or as the result of a twist or fall. You may hear or feel a loud pop when the injury occurs. ACL injuries often bring sudden pain, knee instability, rapid swelling and limited movement. But in some cases, symptoms can take as long as six to 12 hours to occur.
A sudden force that rotates the knee while bearing weight can tear the menisci. Repeated squatting or kneeling also can weaken menisci, increasing the risk of injury. Usually, an injured meniscus causes mild to severe pain. If a blood vessel is torn, swelling may happen immediately. If the joint fills with fluid produced by the joint lining (synovium) as a result of inflammation, swelling may not appear for 24 hours. Continuing pain and a clicking or locking with knee movement are other symptoms of torn menisci. Once the menisci are torn, the knee may buckle or lock without warning. Wearing a brace during activity can help protect the knee from further injury, but surgery may be needed to remove pieces of torn menisci.
The terrible triad is a combination of torn menisci, ACL injury and a sprained ligament at the inner side of the knee -- all from a single blow. Damage this serious usually requires surgery.
Joint Mice
Joint mice are loose bodies -- often pieces of torn cartilage or bone chips -- floating within the knee. A strong blow to the knee can cause a small portion of bone surface to die. Pieces of dead bone then fall away from the main bone to become "joint mice." Joint mice may also occur in association with osteoarthritis. Symptoms often take as long as a year to appear after a trauma. When the pieces of bone get trapped between moving bone, they cause sudden pain and even cause the knee to lock or buckle.
Runner's Knee
Runner's knee, also called patellofemoral pain syndrome or anterior knee pain is an inflammation of the patellar tendon that connects the quadriceps muscle to the knee cap (patella). It is the most common cause of knee pain and the most common overuse injury in the knee. It can also develop because the kneecap doesn't fit correctly in its groove at the end of the femur. Runner's knee can occur from repeated direct blows to the front of the knee or for no apparent reason. It can be brought on by a number of activities that place stress on the knee (skiing and cycling for example). The area around the kneecap or at the back of the knee may ache or swell, especially during and after activity. Squatting or sitting with the knees bent for a long time can be painful. You may feel grinding or popping when you bend or straighten the knee. Allowing the inflamed tendon to rest and using ice on the inflamed tendon for 10 to 20 minutes after exercise can help reduce the inflammation. But it can take six or more weeks to correct the problem. Quadriceps and hip muscle strengthening exercises and stretching exercises can help correct runner's knee and also prevent it.
Jumper's Knee
Jumper's knee, or patellar tendinitis, is an inflammation of the quadriceps tendon at the top of the kneecap, or of the patellar tendon at the bottom of the kneecap. Jumping or a direct blow to the knee are the common causes of inflammation and tearing of these tendons.
Housemaid's Knee/Bursitis
Housemaid's or milkmaid's knee, or prepatellar bursitis, is a condition common to people who work on their knees a great deal, such as carpet layers, roofers, gardeners and people who install flooring. Symptoms include a squishy, swollen area in front of the kneecap, pain and stiffness. In more severe cases, swelling may extend above and to the sides of the kneecap. An inflamed bursa (one of the fluid-filled sacs that cushions movement within a joint) may break internally on its own. If this happens, the body absorbs the excess fluid and the swelling and inflammation usually stop. The best prevention for housemaid's knee is wearing knee pads whenever working on your knees for a long period.
Iliotibial Band Syndrome
Iliotibial band syndrome is pain experienced during activity, such as running or an exercise routine. The iliotibial band is made up of a muscle that begins at the top rim of the pelvis and a tendon that fits into the outside of the knee. It may be caused by injury to the knee, but it is most often caused by overuse. Exercise causes the band to rub over an outer bone of the knee (the lateral femoral condyle) and can cause the band to tighten or partially tear. The pain usually begins 10 to 20 minutes into a run or other exercise routine and stops when the activity stops. Iliotibial band syndrome often grows worse, with pain increasing and starting sooner during a workout.
Self-Care Steps
For Mild Sprains:
Follow the RICE method, and take medication for pain and swelling.
Rest the knee as long as it aches.
After the first three days, soak the knee in a warm whirlpool or bath.
Use crutches if needed.
When the pain is better, use gentle stretching exercise to strengthen the muscles around the knee. Leg extensions are a good strengthening exercise.
See your health care provider.
For Severe Sprains, ACL Injury, and Cartilage Tears:
For Runner's Knee, Tendinitis, Bursitis, and Joint Mice:
Follow the RICE method and take medication for pain and swelling.
Check your shoes to make sure they provide proper support and wear evenly.
When the pain is better, use gentle stretching exercise (see illustration) to strengthen the muscles around the knee.
If swelling from bursitis lasts for more than 10 days or is very bad, a doctor may drain the fluid with a needle and then inject the bursa with cortisone.
For Iliotibial Band Sndrome:
Stretch the iliotibial band, holding the stretch for 20 to 30 seconds and repeating three to six times. Do this three to five times a day, until you no longer feel pain when you run. To prevent it from happening again, do this stretch before and after each run.
If symptoms aren't better in 10 to 14 days after you have begun stretching, see your doctor.
Leg extension: rest foot on stool or pile of books with knee bent at 60-degree angle. Straighten leg; hold for a count of 6, return to rest. Repeat 8-10 times.
Iliotibial band stretch: Stand and cross your right leg in front of left leg. Push left hip out to the side, leaning torso to the right, for a slow, controlled stretch. Hold for 5 counts, repeat 3 to 5 times on one side and then switch to other side. Do not bounce.
Decision Guide for Knee PainSymptoms/Signs | Action |
|---|
Pain after sudden twist or blow to side of knee; swelling; can bear weight but may limp | See provider |
Tendon below kneecap inflamed; pain climbing stairs or jumping | See provider |
Soft, squishy swelling beginning in front of knee; pain; stiffness | See provider |
Pain around or under kneecap; pain increases when climbing stairs or sitting for long periods | See provider |
Bursitis symptoms do not improve within 7 to 10 days or signs of infection appear (local heat, redness, increased swelling, pain, and tenderness) | See provider |
Pain after sudden twist or blow to side of knee; swelling; cannot bear weight | Seek help now |
Pain after sudden twist or blow to side of knee; rapid swelling; limited movement | Seek help now |
Severe blow or injury to knee; severe swelling; unable to move knee; visible deformity of knee | Call 911 |
