Causes of Knee Pain

Most knee injuries 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 2 to 3 weeks to fully heal. A strong blow to the inner or outer side of the knee will sprain the ligament on the opposite side as the knee 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.

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 (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 6 to 12 hours to occur.

The same kind of traumas that cause sprains also can tear the menisci. Repeated squatting or kneeling also can weaken menisci, increasing the risk of injury. Swelling may happen immediately or appear within 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.” 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 the most common cause of knee pain and the most common overuse injury in the knee. 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—or even by wearing shoes that don’t support the foot adequately during sports. It can also develop because the kneecap doesn’t fit correctly in its groove at the end of the femur. 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. Strengthening exercises can help correct runner’s knee and prevent it in the future.

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. Exercise 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.

Caring for Knee Pain

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 3 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 doctor if symptoms don’t improve in 3 to 4 days.

For severe sprains, ACL injury, and cartilage tears:

• Follow the RICE method, and take medication for pain and swelling.

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 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 syndrome:

• 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.