Degenerative arthritis of the knees involves gradual destruction of the cartilage and supportive structures of the joints, leading to deformity and loss of mobility. Several types of degenerative arthritis can affect one or both knee joints, each with distinguishing characteristics. Treatment for degenerative arthritis of the knees depends on the severity of the disorder, the level of disability and the underlying mechanism of joint damage.
Osteoarthritis
The thigh and shinbones meet at the knee joint, separated by firm cartilage disks. The knee cartilage provides a smooth, durable surface that enables nearly frictionless joint movement. With osteoarthritis, the cartilage gradually wears away. Inflammation develops within the knee joint as bones and other support structures rub against one another. Chronic inflammation accelerates the degenerative process, resulting in increasing symptoms of stiffness, swelling, pain and joint deformity.
In an August 2008 article published in the journal "Arthritis Care & Research," Louise Murphy, Ph.D. of the Centers for Disease Control and Prevention and colleagues report that nearly one out of every two adult Americans will develop symptomatic knee osteoarthritis in their lifetimes. Knee osteoarthritis proves a leading cause of disability among Americans, commonly necessitating knee replacement among those with severe disease. "The Burden of Musculoskeletal Diseases in the United States" reports that nearly 455,000 knee replacement surgeries took place in 2004, with nearly two-thirds of the procedures performed on women. Osteoarthritis was the primary indication for knee replacement surgery in approximately 97 percent of cases.
Rheumatoid Arthritis
In 2007, rheumatoid arthritis affected approximately 1.5 million adults in the United States, reports the Centers for Disease Control and Prevention. With this condition, the immune system mistakenly attacks the joint lining tissue. The ongoing inflammation associated with the autoimmune attack gradually destroys the involved joints. Rheumatoid arthritis affects women more commonly than men. The condition may present at any age, but is most commonly diagnosed among patients age 35 to 50, reports the Merck Manuals Online Medical Library.
Rheumatoid arthritis most frequently involves the joints of the hands, but may affect other body sites, including the knees, reports National Institute of Arthritis and Musculoskeletal and Skin Diseases. The disease typically affects both knees simultaneously. Rheumatoid arthritis accounts for less than 1 percent of all knee replacement surgeries, notes "The Burden of Musculoskeletal Diseases in the United States."
Psoriatic Arthritis
Psoriatic arthritis is a degenerative joint disorder that affects approximately 15 percent of patients with the skin disease psoriasis, reports the American College of Rheumatology. The condition commonly affects the joints of the hands, but may also involve one or both knees. The mechanism of joint damage with psoriatic arthritis proves similar to that of rheumatoid arthritis. Psoriatic arthritis affects men and women with equal frequency and may occur from childhood through adulthood.
References
- "Arthritis Care & Research"; Lifetime Risk of Symptomatic Knee Osteoarthritis; Louise Murphy, Ph.D., et al.; August 2008
- "The Burden of Musculoskeletal Diseases in the United States": Arthritis and Related Conditions
- Centers for Disease Control and Prevention: Arthritis-Related Statistics
- The Merck Manuals Online Medical Library: Rheumatoid Arthritis
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Rheumatoid Arthritis
