Signs and Symptoms of Knee Pain

Knee pain can range from mild to severe and can vary from a dull ache to a stabbing, searing pain. It can develop suddenly (acute knee pain) or gradually over time (chronic knee pain), and may be constant or intermittent (i.e., come and go). Some types of knee pain worsen with activity or at night and radiate (spread) to other parts of the body (e.g., hips, back).

Depending on the cause, knee pain may be accompanied by other symptoms, such as inflammation, swelling, and stiffness (immobility). Symptoms that may indicate as serious condition and require immediate medical care include the following:

  • Deformed or misshapen knee joint
  • Inability to stand or bear weight on the affected leg
  • Inability to straighten or bend the knee
  • Infection (fever, warmth, redness)
  • Knee that locks or clicks
  • Pain accompanied by tingling, numbness, swelling, and discoloration below the knee
  • Severe pain and pain that worsens in spite of treatment

Knee Pain Diagnosis

A medical history, physical examination, and diagnostic tests often are used to help diagnose the underlying cause for knee pain. A medical history includes information about the exact location, onset, and severity of the pain; any additional symptoms; and existing medical conditions.

During physical examination, the physician evaluates the patient's manner of walking (gait), if possible, and examines the knees in a number of different positions for swelling, redness, misalignment, and signs of injury (e.g., bruise, cut). The legs, hips, and other joints in the body (e.g., ankles, wrists) also are examined.

Diagnostic tests that may be performed include imaging tests (e.g., x-rays, MRI scan), blood tests, removal of fluid from the knee (joint aspiration), and arthroscopy. X-rays, and in some cases, computerized tomography (CT scan) can be used to detect fractures, dislocations, and changes in the knee joint caused by arthritis.

Magnetic resonance imaging (MRI scan) uses powerful magnets to create computer images of the structures within the knee. This test can be used to detect tears in ligaments, tendons, and cartilage. Blood tests (e.g., complete blood count [CBC], sed rate [ESR]) can be used to rule out infection and inflammatory conditions, such as rheumatoid arthritis.

In joint aspiration, fluid from within the knee joint (synovial fluid) is removed and examined under a microscope for signs of inflammation and infection. In this procedure, the area is numbed using local anesthesia and a needle is inserted into the joint to withdraw synovial fluid.

Arthroscopy, also called arthroscopic surgery, is an outpatient procedure that can be used to diagnose and treat some types of knee damage. In this procedure, the surgeon makes a small incision and uses an arthroscope (device that includes a tiny camera connected to a monitor) to examine the knee joint. If treatment is required, the surgeon makes other small incisions and inserts surgical instruments to remove or repair damaged tissue.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 29 Oct 2007

Last Modified: 10 Sep 2010