Osteoarthritis of the Knee
Osteoarthritis is the most common type of arthritis, affecting more than 21 million Americans. Osteoarthritis tends to develop as people get older or from overuse of the knee during work or sports. Osteoarthritis causes the protective covering at the ends of the bones in the knee to gradually wear away, resulting in painful bone on bone rubbing and disrupted movement. Medications, physical therapy, and knee injections are used to treat osteoarthritis of the knee. Surgery may be necessary if pain and immobility limit your activities and lifestyle, despite non-surgical treatments.
The knee is one of the most complex joints in the body. It is composed of three bones. The thighbone (femur) is positioned on top of the larger leg bone (tibia). The kneecap (patella) glides in a groove on the end of the thighbone. Large muscle groups in the thigh give the knee strength and stability.
A smooth articular cartilage covers the bones in the knee joint. The articular cartilage serves as a cushion between the joints, allowing the bones to glide pain-free during motion. When the articular cartilage breaks down, the space between the joint narrows and becomes uneven.
Osteoarthritis of the knee occurs as the articular cartilage in the knee joint breaks down, causing a reaction in the bone. The bones in the knee joint become thicker and develop growths (osteophytes or spurs). Lubricating fluid in the joint (synovial fluid) gets thicker and inflamed. If too much fluid is produced, a condition referred to as "water on the knee" can result.
With osteoarthritis, the knee joint continues to experience changes over several years. Eventually, very little of the articular cartilage remains. Bone-on-bone rubbing causes pain, impairs knee movements, and makes daily activities difficult.
Factors that increase the risk of developing osteoarthritis include:
- Excess weight or obesity that adds pressure to the knee joints
- Increasing age
- Women more than 50 years old have a higher incidence than men
- Knee injury
- Repetitive stress injury to the knee
- Participation in high impact sports
- Certain illnesses, including septic arthritis and metabolic disorders
Osteoarthritis of the knee can cause knee pain and swelling. You may have difficulty moving your knee or performing activities such as walking, squatting, kneeling, and going up or down stairs.
Doctors diagnose osteoarthritis of the knee by examining the knee, considering your symptoms, and reviewing your medical records. X-rays are the main diagnostic tool to diagnose osteoarthritis.
Treatment of osteoarthritis of the knee is individualized. The treatment that you receive depends on several factors, including your overall health and the stage of disease. Osteoarthritis of the knee is treated with physical therapy, lifestyle changes, medications, surgery, or a combination of treatments.
If you are overweight, your doctor may recommend that you lose weight. Attaining and maintaining a healthy weight reduces the load on your knees. Participating in physical therapy can help strengthen the muscle groups around the knee joint. A knee brace can provide support.
Your doctor may recommend over-the-counter pain medications such as aspirin or nonsteroidal anti-inflammatory drugs. Your doctor may prescribe stronger prescription pain medications if necessary. Joint injections, such as corticosteroid injections or viscosupplementation, are used for osteoarthritis pain relief.
If symptoms persist despite conservative treatments, knee surgery may be necessary. Osteotomy and joint replacement (arthroplasty) are surgical procedures to treat osteoarthritis of the knee. Osteotomy is used to remove and reshape bone from the leg to cause a shift in body weight away from the damaged area. Casting, splinting, and physical therapy follow osteotomy. Recovery from osteotomy varies from 3 to 6 months for some people, and up to a year for others.
Total knee replacement removes the damaged portion of the knee and replaces it with artificial implants. Knee replacement is the most common type of joint replacement surgery. It is highly successful for relieving pain and restoring function. Minimally invasive knee replacement surgery uses smaller incisions, and is associated with shorter hospital stays, shorter rehabilitation periods, and a quicker recovery time than traditional total knee replacement. Your doctor will let you know which knee joint replacement method is best for you. Overall, most people experience a dramatic reduction of knee pain and the ability to resume functional activities after knee arthroplasty.