Knee Pain

Brief anatomy of the knee:
The knee is the largest joint in the body. It has the ability to flex and extend, and to rotate (turn) and translate (glide). It is formed by the:

• tibia - shin bone or larger bone of the lower leg
• femur - thigh bone or upper leg bone
• patella - kneecap

Each bone end is covered with a layer of cartilage that cushions, absorbs shock and protects while allowing movement. Cartilage contains no nerve endings or blood supply. If damaged, the cartilage is not capable of repairing itself.

Pads of connective tissue called menisci separates the bones of the knee. They are divided into two crescent-shaped discs located between the tibia and femur on the outer and inner sides of each knee. They act as shock absorbers, cushioning the lower part of the leg from the weight of the rest of the body.

Surrounding the knee structure is the synovial lining, which produces a moisturizing lubricant for the cartilage.

Ligaments link the bones of the knee joint to hold them in. Muscles and tendons also play an important role in keeping the knee joint stable and mobile.

What causes knee pain?
The knee, like other joints in the body, may break down during the aging process, or may be damaged by injury, such as a blow to the knee or sudden movements that strain the knee beyond its normal range of movement. But, the most frequent source of debilitating knee pain is arthritis.

How knee problems are diagnosed:
Knee problems are diagnosed in several ways, beginning with a medical history and physical examination, followed by diagnostic tests, including:

• X-ray (radiography)

• Computerized axial tomography (CAT) scan produces a series of cross-sectional images of knee tissues on a computer screen. These images show soft tissues more clearly than regular x rays, and images can be combined to give a three-dimensional view of the knee.

• Bone scan (radionuclide scanning) uses a very small amount of radioactive material, which is injected into the patient's bloodstream to be detected by a scanner. This test shows blood flow to the bone and cell activity within the bone.

• Magnetic resonance imaging (MRI) uses energy from a powerful magnet, which stimulates tissues to produce signals that are detected by a scanner and analyzed by computer. It creates a series of cross-sectional images of a specific part of the knee. This tool is good for detecting damage or disease of soft tissues, such as ligaments and muscles and can produce three-dimensional views of the knee.

• Arthroscopy is a procedure that uses a small, lighted optic tube (arthroscope), which is inserted into the joint through a small incision in the knee. Images of the inside of the knee joint are projected onto a screen.

If initial treatment methods do not provide relief and X-rays show destruction of the joint, the orthopaedist may recommend total joint replacement for the knee.