Arthritis of the Knee

Arthritis is inflammation of one or more of your joints which will often lead to joint surface or cartilage wear.  When the articular cartilage wears out, the bone ends rub on one another and cause pain. This condition is referred to as Osteoarthritis or “wear and tear” arthritis as it occurs with aging and use. It is the most common type of arthritis.  Pain, swelling, and stiffness are the primary symptoms of arthritis. Any joint in the body may be affected by the disease, but it is particularly common in the knee.  Knee arthritis can make it hard to do many everyday activities, such as walking or climbing stairs. It is a major cause of lost work time and a serious disability for many people.

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 Osteoarthritis often results in bone rubbing on bone. Bone spurs are a common feature of this form of arthritis.

Causes

There are more than 100 different forms of arthritis. Generally it affects people as they grow older (Osteoarthritis), but other causes include:

• Inflammation (rheumatoid arthritis and other inflammatory conditions)
• Trauma (post fracture or dislocation, or following previous meniscal, ligament or chondral injury)
• Connective tissue disorders (such as systemic lupus erythematosus – SLE)
• Increased stress such as overuse or overweight
• Obesity - weight is the single most important link between diet and arthritis as being overweight puts an additional burden on your hips, knees, ankles and feet.
• Infection of the bone (osteomyelitis) or previous joint infection (septic arthritis)

Symptoms

A knee joint affected by arthritis may be painful and inflamed. Generally, the pain develops gradually over time, although sudden onset is also possible. There are other symptoms, as well:

• Pain and swelling may be worse in the morning, or after sitting or resting.
• Vigorous activity may cause pain to flare up.
• Pain may cause a feeling of weakness or buckling in the knee.
• Many people with arthritis note increased joint pain with rainy weather. 
• The joint may become stiff and swollen, making it difficult to bend and straighten the knee. 
• Loose fragments of cartilage and other tissue can interfere with the smooth motion of joints. The knee may "lock" or "catch" during movement. It may creak, click, snap or make a grinding noise (crepitus).

Diagnosis

Knee arthritis is diagnosed with a thorough medical history, physical exam and x-rays (and occasional other imaging studies) of the affected joint.  During the physical examination, A/Prof Woodgate will look for problems with your gait (the way you walk), wasting of thigh or calf muscles, Pain when weight is placed on the knee (difficulty with single leg stance or squatting), jjoint swelling, warmth, or redness, tenderness about the knee, range of active (self-directed) and passive (assisted) motion, instability of the joint, crepitus (a grating sensation inside the joint) with movement, any signs of injury to the muscles, tendons, and ligaments surrounding the knee, and involvement of other joints (an indication of rheumatoid arthritis or other inflammatory condition).Xrays of an arthritic knee typically may show narrowing of the joint space, changes in the bone and the formation of bone spurs (osteophytes).

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Treatment

Although there is no cure for arthritis, many treatment options and lifestyle modifications are available to help manage pain and symptoms, and to keep people staying active. The objective of the treatment is to reduce pain, improve joint movement, and prevent further damage to the joint.

Nonsurgical Treatment

As with other arthritic conditions, initial/early treatment of arthritis of the knee is nonsurgical, and include:

• Lifestyle modifications - Some changes in your daily life can protect your knee joint and slow the progress of arthritis.
  * Minimize activities that aggravate the condition, such as climbing stairs.
  * Switching from high impact activities (like jogging or tennis) to lower impact activities (like swimming or cycling) will put less stress on your knee.
  * Losing weight can reduce stress on the knee joint, resulting in less pain and increased function.
• Physical therapy - Specific exercises can help increase range of motion and flexibility, as well as help strengthen the muscles in your leg. An individualized exercise program that meets your needs and lifestyle will be required.
• Assistive devices. Using devices such as a cane, wearing shock-absorbing shoes or inserts, or wearing a brace or knee sleeve can be helpful. A brace assists with stability and function, and may be especially helpful if the arthritis is centred on one side of the knee. There are two types of braces that are often used for knee arthritis: An "unloader" brace shifts weight away from the affected portion of the knee, while a "support" brace helps support the entire knee load.
• Other remedies - Applying heat or ice, using pain-relieving ointments or creams, or wearing elastic bandages to provide support to the knee may provide some relief from pain.
• Medications - Several types of drugs are useful in treating arthritis of the knee:
  * Paracetamol - usually the first choice of therapy for arthritis of the knee. It is a simple, over-the-counter pain reliever that can be effective in reducing arthritis pain.
  * Nonsteroidal anti-inflammatory drugs (NSAID)
  * Corticosteroids - are powerful anti-inflammatory agents that can be injected into the joint.  These injections provide pain relief and reduce inflammation, but the effects do not last indefinitely. In some cases, pain and swelling may "flare" immediately after the injection, and the potential exists for long-term joint damage or infection. With frequent repeated injections, or injections over an extended period of time, joint damage can actually increase rather than decrease.
  * Disease-modifying anti-rheumatic drugs (DMARDs) are used to slow the progression of rheumatoid arthritis and other inflammatory conditions. Drugs like methotrexate, sulfasalazine, and hydroxychloroquine are commonly prescribed. In addition, biologic DMARDs like etanercept (Enbrel) and adalimumab (Humira) may reduce the body's overactive immune response. Because there are many different drugs today for rheumatoid arthritis, a rheumatologist is often required to effectively manage these medications.
  * Viscosupplementation involves injecting substances into the joint to improve the quality of the joint fluid.
  * Glucosamine and chondroitin sulphate, substances found naturally in joint cartilage, can be taken as dietary supplements. Although patient reports indicate that these supplements may relieve pain, there is no evidence to support the use of glucosamine and chondroitin sulphate to decrease or reverse the progression of arthritis. In addition, these compounds may cause side effects, as well as have negative interactions with other medications.

Surgical Treatment

Surgery is recommended if your pain from arthritis causes disability and is not relieved with nonsurgical treatment. As with all surgeries, there are some risks and possible complications with different knee procedures:

• Arthroscopy - Arthroscopic surgery is not often used to treat arthritis of the knee. In cases where osteoarthritis is accompanied by a degenerative meniscal tear, arthroscopic surgery may be recommended to treat the torn meniscus in isolation.
• Cartilage grafting - Normal, healthy cartilage tissue may be taken from another part of the knee or from a tissue bank to fill a hole in the articular cartilage. This procedure is typically considered only for younger patients who have small or isolated areas of cartilage damage.
• Synovectomy - The joint lining damaged by rheumatoid arthritis is removed to reduce pain and swelling.
• Osteotomy. - In a knee osteotomy, either the tibia (shinbone) or femur (thighbone) is cut and then realigned to relieve pressure on the knee joint. Knee osteotomy is used when you have early-stage osteoarthritis that has damaged just one side of the knee joint. By shifting your weight off the damaged side of the joint, an osteotomy can relieve pain and significantly improve function in your arthritic knee.  It may delay the need for joint replacement.
• Total or partial knee replacement (arthroplasty) - The damaged cartilage and bone is removed, and replaced with new metal or plastic artificial joint surface components to restore the function of your knee.

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(Left) A partial knee replacement is an option when damage is limited to just one part of the knee. (Right) A total knee replacement prosthesis.