Arthritis of the knee

Arthritis of the knee is a condition that causes inflammation, pain, swelling and limited movement of the knee joint and connective tissues around the knee. Arthritis is one of more than 100 types of rheumatic diseases (diseases that affect joints and connective tissues). Depending on the type of knee arthritis, symptoms can range from pain and swelling in the joints to difficulty using or moving the joint in a normal way.

Knee arthritis usually affects men and women over 50 years of age, and occurs most frequently in people who are overweight. You may experience one or more of these common symptoms of knee arthritis:

• Pain or stiffness in or around your knee
• Swelling of your knee
• Warmth and redness in your knee joint
• Continuing or recurring pain or tenderness in your knee joint
• Limited range of motion when your walk or move your knee
• Weakness in your knee or a feeling of instability

In more severe cases, the knee joint may appear deformed, such as bowlegged or knock-kneed, either bulging outward or toward the side of the leg. Knee replacement surgery often is performed on patients who have severe symptoms.

The symptoms of arthritis of the knee may resemble other medical conditions or problems. Always consult your physician for a diagnosis.

Although the cause of arthritis is unknown, the Centers for Disease Control and Prevention reports that certain factors are associated with a greater risk of arthritis of the knee. Some risk factors can't be avoided, while others can be reduced or eliminated.

These types of rheumatic diseases can affect the knee joint and connective tissues:

• Osteoarthritis – The most common form of arthritis, osteoarthritis is also known as "wear and tear" arthritis. It often occurs in your knees, because your knee joints — like your hips and spine — are weight-bearing joints. This chronic rheumatic disease damages and thins the knee joint's articular cartilage, the smooth and glistening covering on the ends of your bones that enables your knee joint to glide smoothly. Osteoarthritis also narrows the space in which the knee joint moves. Osteoarthritis predominantly affects older people, but it also can occur in young people as a result of a knee injury or overuse.
• Rheumatoid arthritis – This inflammatory disease attacks the lining of your knee joint (synovium) and is one of a group of arthritis diseases known as inflammatory arthritides. Rheumatoid arthritis is a systemic autoimmune disease that can attack any joint. A chronic disease, it is characterized by periods of flare-ups and remissions and can affect people of all ages. Rheumatoid arthritis of the knee can cause permanent destruction and deformity of the knee joint even before symptoms are severe. The cause of rheumatoid arthritis of the knee is unknown.
• Post-traumatic arthritis – Despite proper treatment and full recovery from an injury, post-traumatic arthritis may develop years after a fracture, ligament injury or meniscus tear (a tear in the connective tissue of the knee).
• Fibromyalgia – This chronic condition causes pain, stiffness and tenderness of the muscles, tendons and joints without the detectable inflammation easily noticed in many other rheumatoid diseases that affect the joints.

Risk factors that can't be modified include:

• Age – The risk of developing most types of arthritis increases with age.
• Gender – Most types of arthritis are more common in women; 60 percent of all people with arthritis are women. Gout is more common in men.
• Genetics – You might inherit specific genes associated with a higher risk of certain types of arthritis, such as rheumatoid arthritis (RA), systemic lupus erythematous (SLE) and ankylosing spondylitis.

Risk factors that can be modified include:

• Overweight and obesity – Excess weight can contribute to both the onset and progression of a type of wear-and-tear arthritis of the knee, known as osteoarthritis.
• Joint Injuries – Damage to a joint can contribute to the development of osteoarthritis in that joint.
• Infection – Many microbial agents can infect joints and potentially cause the development of various forms of arthritis.
• Occupation – Certain occupations involving repetitive knee bending and squatting are associated with osteoarthritis of the knee.

Nonsurgical treatments such as anti-inflammatory medicines, corticosteroids, physical therapy and an assistive device such as a cane or walker can help reduce the pain and discomfort of arthritis of the knee. If nonsurgical treatments fail to provide relief, you may need surgery. Depending on the type of arthritis, your orthopaedist may recommend:

• Arthroscopic surgery – A minimally invasive procedure that uses very small incisions and fiber optic technology to see inside the knee joint and remove debris or repair torn cartilage. An arthroscope is inserted in one incision, and very thin surgical instruments are inserted in one or more of the other incisions. The arthroscope is a small tube, thinner than a pencil, containing a system of lenses, a light and a small video camera. The camera sends large real-time images to a video monitor next to the operating table, thus allowing the surgeon to make precise movements with the special surgical instruments. Thanks to the miniaturized camera, the surgeon can see more detail than could be seen with a larger incision (open surgery) and the naked eye.
• Osteotomy – Osteotomy of the knee is surgery that involves removing a wedge of bone from one of the leg bones right below or above your knee to improve alignment of the knee joint. This may be done to relieve symptoms of arthritis of the knee or trauma. 

A tibial osteotomy makes a cut in the shin bone (lower leg), while a femoral osteotomy makes a cut in the thigh bone. According to the National Institutes of Health, arthritis most often affects the inside part of your knee, not the outside part. That's because the inside of the knee holds more of your weight than the outside of the knee when you walk and stand. Osteotomy surgery works by shifting the weight away from the damaged part of your knee to the other side of the knee. When your surgeon removes a wedge of your shinbone from underneath the healthy side of your knee, the shinbone and thighbone can bend away from the damaged cartilage. For the surgery to be successful, the side of the knee where the weight is being shifted should have little or no arthritis.

The benefits of an osteotomy are twofold: you'll be able to stay active as a result of better knee alignment and less painful symptoms of arthritis. Additionally, when you have an osteotomy, you may be able to delay a total knee replacement surgery for up to 10 years.

• Total knee replacement surgery –During total knee replacement your surgeon resurfaces your knee joint by removing the diseased bone and cartilage. This includes the lower end of the thighbone (femur), the upper end of the shinbone (tibia), and the back side of the kneecap (patella). These surfaces are replaced with a metal and plastic implant, which mimics natural knee motion and function. Total knee replacement surgery can help put an end to painful arthritis in your knee and enable you to resume a functional and active lifestyle.
• Partial knee replacement surgery – If you have arthritis in just one part of your knee, you may be a candidate for partial knee replacement surgery, also known as unicompartmental knee replacement. During the procedure, your orthopaedic surgeon replaces the damaged knee compartment with a metal and plastic implant, while the healthy cartilage and bone in the rest of your knee are left alone.
• Cartilage grafting – This surgical procedure is an option for some knees that have limited or contained articular cartilage loss from arthritis or trauma. Articular cartilage is the smooth, white tissue that covers the ends of bones where they come together to form joints. Healthy cartilage makes it easier for you to move your body and allows your bones to glide over one another with very little friction. When cartilage is damaged by injury or arthritis of the knee, cartilage grafts can be used to stimulate the growth of new cartilage. The benefits of cartilage grafting are pain relief and better knee function.