Definition & Overview

The knees are the largest joints in the body and they connect the upper and lower bones of the legs, allowing us to walk, jump, crouch, and run. As they carry the weight of the entire body, the knees are subjected to a good amount of stress on a daily basis and this, together with other factors, such as diseases and wear and tear due to age, typically lead to a variety of knee problems that can affect the bone, ligaments, tendons, muscles, and cartilage.

The knees are made up of three bones: femur (thighbone), patella (kneecap), and tibia (shinbone). The ends of these bones are covered with a slippery material called cartilage. The articular cartilage helps the bones slide against each other smoothly, allowing us to easily bend or straighten our legs. The meniscal cartilage, meanwhile, absorbs force, thus cushioning the bones and stabilizing the joint. The bones are connected to each other through ligaments. The collateral ligaments are located on the sides and inside the knee, providing control over the movement of the knee and preventing it from moving in an unusual manner. The cruciate ligaments are found inside the knee joint and controls back and forth movements. Stress, wear and tear, injuries, and trauma can affect any of these parts, and this can result in a variety of knee problems.

Cause of Condition

The primary causes of the majority of knee problems are:

  • Injuries and diseases
  • Wear and tear. As a person ages, the knees have a tendency to lose some flexibility and when this happens, they become rigid and more prone to injuries.
  • Direct blow to the knee
  • If the knee is stretched beyond its normal range

Some of the most common knee injuries are dislocations, fractures, anterior cruciate ligament (ACL) injury, posterior cruciate ligament (PCL) injury, collateral ligament injury, and meniscal and tendon tears.

Meanwhile, common diseases that affect the knee include arthritis, with osteoarthritis, and rheumatoid arthritis, being the most common. Knee problems that are categorized under rheumatoid arthritis are gout, reactive arthritis, ankylosing spondylitis, and systemic lupus erythematosus.

Key Symptoms

The primary symptom of any type of knee problem is pain in the joint that is a direct result of an injury or a disease. In some cases, pain can also be accompanied by swelling, redness, or stiffness. The exact symptoms will depend on the problem or disease.

Movement will be limited depending on the severity of the pain. While others experience pain that can easily be tolerated, others experience severe pain that prevents them from standing up, walking around, or even moving the legs.

Who to See & Types of Treatment Available

If you experience any of the above symptoms or find it difficult to place your weight on a knee or notice any deformities, you should see your doctor as soon as possible. Your doctor will evaluate your condition and if needed, refer you to an orthopedist, a specialist in diagnosing and treating knee problems.

The doctor will ask about when you first noticed the problem and the symptoms you’re experiencing. A thorough physical examination will then be performed and this will include a visual inspection of the affected knee, extending your leg to determine how far you can move it in different directions, and checking the integrity of the joint structure.

Imaging tests, such as an x-ray, ultrasound, MRI, or CT-scan will also be performed to determine the extent of the problem. If the doctor suspects a disease or an infection, laboratory tests will be ordered as well. The lab test will involve checking your blood for any abnormalities. It’s also possible that the doctor will have you undergo a procedure called arthrocentesis, which involves obtaining fluid from your knee joint using a fine needle to determine the presence of arthritis, gout, and synovial infections.

Once the doctor has determined the exact cause and extent of the problem, an individualized treatment plan will be immediately formulated. Treatment can be as simple as taking pain medications to alleviate the pain (such as in the case of gout and rheumatoid arthritis), or it can be as complex as a knee surgery.

Surgery is only considered when other treatment methods have failed or if the knee has been severely damaged. Some of the most common surgical procedures performed on knees are arthroscopic surgery, partial knee replacement surgery, and total knee replacement.

  • In an arthroscopic surgical procedure, the doctor will use an instrument called an arthroscope. This surgical instrument is composed of a thin tube with a fiber-optic camera. Special surgical tools can be inserted into the tube to perform repairs on the knee, such as removing damaged cartilage or reconstructing ligaments.

  • In partial knee replacement surgery, the damaged portion of the knee will be replaced using artificial knee parts made of metal and/or plastic. This type of surgical procedure is usually performed through a small incision in the knee and will only require an overnight stay at the hospital.

  • A total knee replacement surgery is what the name implies; the surgeon will remove the entire joint and replace it with an artificial knee made of metal alloy, polymer, and plastic. Physical therapy is often required after surgery to help you build muscles and relearn how to use your knee.

  • Frontera WR, Silver JK, eds. Essentials of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, PA: Elsevier Saunders; 2008:section 7.

  • Honkamp NJ, Shen W, Okeke N, Ferretti M, Fu FH. Knee: Anterior cruciate ligament injuries in the adult. In: DeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez's Orthopaedic Sports Medicine. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2009:chap 23, section D.

  • Huddleston JI, Goodman SB. Hip and knee pain. In: Firestein GS, Budd RC, Harris ED Jr, et al, eds. Kelley's Textbook of Rheumatology. 8th ed. Philadelphia, PA: Elsevier Saunders; 2008:chap 42.

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