Knee Pain

Knee pain is a common complaint that affects people of all ages. Knee pain may be the result of an injury, such as a ruptured ligament or torn cartilage.

Medical conditions — including arthritis, gout and infections — can also cause knee pain.

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.

Symptoms

The location and severity of knee pain may vary, depending on the cause of the problem.

Signs and symptoms that sometimes accompany knee pain include:

• Swelling and stiffness
• Redness and warmth to the touch
• Weakness or instability
• Popping or crunching noises
• Inability to fully straighten the knee

When to see a doctor

Call your doctor if you:

• Can’t bear weight on your knee or feel as if your knee is unstable or gives out
• Have marked knee swelling
• Are unable to fully extend or flex your knee
• See an obvious deformity in your leg or knee
• Have a fever, in addition to redness, pain and swelling in your knee
• Have severe knee pain that is associated with an injury

Causes

Knee pain can be caused by injuries, mechanical problems, types of arthritis and other problems.

Injuries

A knee injury can affect any of the ligaments, tendons or fluid-filled sacs (bursae) that surround your knee joint as well as the bones, cartilage and ligaments that form the joint itself. Some of the more common knee injuries include:

ACL injury: An ACL injury is a tear of the anterior cruciate ligament (ACL) — one of four ligaments that connect your shinbone to your thighbone. An ACL injury is particularly common in people who play basketball, soccer or other sports that require sudden changes in direction.

Fractures: The bones of the knee, including the kneecap (patella), can be broken during falls or auto accidents. Also, people whose bones have been weakened by osteoporosis can sometimes sustain a knee fracture simply by stepping wrong.

Torn meniscus: The meniscus is the tough, rubbery cartilage that acts as a shock absorber between your shinbone and thighbone. It can be torn if you suddenly twist your knee while bearing weight on it.

Knee bursitis: Some knee injuries cause 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: Tendinitis causes irritation and inflammation of one or more tendons — the thick, fibrous tissues that attach muscles to bones. This inflammation can happen when there’s an injury to the patellar tendon, which runs from the kneecap (patella) to the shinbone and allows you to kick, run and jump. Runners, skiers, cyclists, and those involved in jumping sports and activities may develop patellar tendinitis.