Arthritis is one of more than 100 types of rheumatic disease that affects one or more joints and their connective tissues. Along with inflammation, arthritis causes pain, swelling and limited movement of joints and connective tissues. Arthritis of the hip and knee are more common than arthritis of any other joints, because hips and knees are the body's major weight-bearing joints. Depending on the type of arthritis, symptoms can range from mild pain and discomfort to severe pain and disability that can affect your job, your favorite activities and your overall quality of life.
Arthritis causes joint damage. Joints consist of three parts:
- Cartilage – This is the slick, hard coating on the ends of bones that allows the bones of a joint to slide smoothly over one another.
- Joint capsule – This is a tough membrane that encloses all the parts of the joint.
- Synovium – This is a thin membrane that lines the joint capsule and secretes synovial fluid. The fluid's function is to nourish the cartilage and keep the joint lubricated.
Arthritis causes the cartilage in your joints to become stiff and lose its elasticity. The stiffness makes the cartilage more susceptible to damage. Over time, the cartilage may wear away in some areas, greatly decreasing its ability to act as a shock absorber. As the cartilage deteriorates, tendons and ligaments stretch, causing pain. If the condition worsens, the bones could rub against one another.
You may experience one or more of these common symptoms of arthritis:
- Joint pain, aching and soreness, especially with movement
- Joint swelling
- Joint tenderness when you apply light pressure to it
- Pain after overuse or after long periods of inactivity
- Joint stiffness, especially after sleeping or inactivity
- Limited joint movement as the disease progresses
- Grinding of joints when moved (in more advanced stages of osteoarthritis) as the cartilage wears away
- Extra bits of bones known as bone spurs, which feel like hard lumps, may form around the affected joint
- Bony enlargements in the middle and end joints of the fingers which may or may not be painful
The symptoms of arthritis may resemble other medical conditions or problems. Always consult your physician for an accurate diagnosis.
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.
There are no known causes of arthritis, but there are certain risk factors that can make you more susceptible to arthritis, including:
- Heredity – Slight joint defects or double-jointedness (laxity) and genetic defects may contribute to the development of arthritis.
- Obesity – Over time, excessive weight can place undue stress on joints such as the knees, hips and spine.
- Injury or overuse – A significant injury to a joint such as the knee can later result in arthritis even if your injury was treated properly at the time. Repeated overuse or misuse of a joint also may cause injury.
- Occupation – Certain occupations involving repetitive movements of the joints are associated with arthritis.
Osteoarthritis most often affects the joints in the knee, hip, spine and hand, because those joints are often overused and abused. Increasingly, people who work at computers every day are developing osteoarthritis because of the repetitious nature of keyboard entry for hours at a time. In addition, the joints in the knee, hip and spine have to carry your body weight. That's why people who are overweight or obese are at higher risk for developing osteoarthritis. Osteoarthritis predominantly affects people 45 years of age and older, but it also can occur in young people as a result of a knee injury or overuse in recreational or job-related activities.
Arthritis affects 50 million Americans, according to the Centers for Disease Control and Prevention. The American Academy of Orthopaedic Surgeons (AAOS) reports that arthritis is the leading cause of disability in the United States. Even though there is no cure for arthritis, great progress has been made in the variety and effectiveness of nonsurgical and surgical treatment options available. With a personalized nonsurgical treatment regimen, many people with arthritis are able to avoid surgery and successfully manage their pain, stay active and live fulfilling lives.
Nonsurgical treatments for arthritis include:
- Analgesics and pain relievers
- Anti-inflammatory medicines
- Cortisone shot
- Lubrication injections of hyaluronic acid derivatives to provide some cushioning for the joint
- Physical therapy
- Assistive devices such as a cane or walker, splints, braces and shoe inserts to help reduce the pain and discomfort of arthritis.
If nonsurgical treatments for arthritis fail to provide substantial relief, your orthopaedist may recommend surgical procedures such as:
- Arthroscopic surgery – A minimally invasive procedure that uses very small incisions and fiber optic technology to see inside a joint and remove debris or repair torn cartilage. An arthroscope is inserted in one incision, and very thin surgical instruments are inserted in one of 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 – Osteotomies are performed more frequently for arthritis of the knee or hip. Osteotomy of the knee is a surgical procedure 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 trauma or arthritis of the knee. 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 you stand. When your surgeon removes a wedge of your shinbone from underneath the healthy side of your knee, the shinbone and thighbone can then 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 joint replacement surgery – Knee and hip joints are the most commonly replaced joints due to their weight-bearing function. During total knee or hip replacement surgery, your orthopaedic surgeon resurfaces your joint by removing the diseased bone and cartilage. These surfaces are replaced with a metal and plastic implant, which mimics natural knee or hip motion and function. Total joint replacement surgery can help put an end to painful arthritis in your knee or hip and enable you to resume a functional and active lifestyle.
- Hip resurfacing – If you have advanced arthritis of the hip, you may be a candidate for either traditional total hip replacement (arthroplasty) or hip resurfacing (hip resurfacing arthroplasty). Each of these procedures is a type of hip replacement, but there are important differences that should be discussed with your orthopaedic surgeon.
- Synovectomy – This surgical procedure removes part or all of the hip or knee joint lining. It usually is recommended for people with rheumatoid arthritis or ankylosing spondylitis, if the disease is limited to the joint lining and hasn't affected the cartilage.
- Cartilage grafting – This surgical procedure is an option for some knees or hips 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 arthritis or injury, cartilage grafts can be used to stimulate the growth of new cartilage. The benefits of cartilage grafting are pain relief and better joint function.