Knee arthritis is a common condition, affecting millions of people each year. It can lead to joint pain, stiffness, limitation of activity, and a decrease in the quality of life. Knee arthritis can result from trauma or previous surgery, conditions such as Rheumatoid Arthritis, or be a part of the normal aging process.
The knee joint is made up of the lower end of the femur (thighbone), the upper end of the tibia (shinbone), and the patella (kneecap). The surfaces of these three bones are covered with articular cartilage, a smooth tissue that protects and cushions the bones as you bend and straighten your knee. Other important structures of the knee include:
- Meniscus: Between the tibia and femur lie two floating cartilages called menisci. The medial (inner) meniscus and the lateral (outer) meniscus rest on the tibial surface cartilage and are mobile. The menisci also act as shock absorbers and stabilizers.
- Ligaments: The knee is stabilized by ligaments that are both in and outside the joint. The medial and lateral collateral ligaments support the knee from excessive side-to-side movement. The (internal) anterior and posterior cruciate ligaments support the knee from buckling and giving way.
- Synovium: The knee joint is surrounded by a capsule that produces a small amount of synovial (lubrication) fluid to help with smooth motion.
Common Causes of Knee Arthritis
Arthritis is any condition that causes degeneration of the cartilage of the joint surfaces. When the articular cartilage wears down, there is no longer a smooth surface lining the bones of the knee joint causing pain. The most common causes of knee arthritis are:
- Osteoarthritis: Also called degenerative joint disease, this is the most common type of arthritis, which occurs most often in older people. This disease affects cartilage, the tissue that cushions and protects the ends of bones in a joint. With osteoarthritis, the cartilage starts to wear away over time. In extreme cases, the cartilage can completely wear away, leaving nothing to protect the bones in a joint, causing bone-on-bone contact.
- Rheumatoid Arthritis: This is an autoimmune disease in which the body’s immune system (the body’s way of fighting infection) attacks healthy joints, tissues, and organs. Occurring most often in women of childbearing age, this disease inflames the lining (or synovium) of joints. It can cause pain, stiffness, swelling, and loss of function in joints. When severe, rheumatoid arthritis can deform, or change a joint. It is symmetrical, meaning that it usually affects the same joint on both sides of the body.
- Post-traumatic Arthritis: this is a form of arthritis that develops after an injury to the knee. This can result from a fracture or a break in one of the bones leading to damage to the joint surfaces leading to arthritis years after the injury. In some cases, ligament injuries or meniscus tears can cause instability and increased wear on the joint over time leading to arthritis. In some cases surgery to remove a meniscus too early can lead to loss of joint space over time causing arthritis.
People with knee arthritis may experience pain and swelling. Symptoms often are gradual and worsen over time. Pain and swelling may be present after physical activity. Overtime people may notice that the pain may be worse in the morning, or after sitting or resting. The knee may become stiff making it difficult to fully bend or straighten the knee. If there are loose fragments of cartilage or bone spurs, this can interfere with the smooth motion of joints. The knee may “lock” or “stick” during movement. It may creak, click, snap or make a grinding noise (crepitus). Other symptoms include the inability to walk for long distances, difficulty rising from a chair, climbing stairs, and eventually, difficulty with routine activities.
Knee arthritis is diagnosed through a thorough history and physical examination. During the physical exam, Dr. Faucett may look for pain or swelling around the knee joint, change in range of motion or stability, as well as any crepitus with movement. Diagnostic tests include Xrays of the knee to evaluate for loss of joint space or extra bone (osteophyte) formation. MRIs are usually not helpful in diagnosing knee arthritis but may be used to evaluate the soft tissue structures of the knee joint.
Conservative or non-operative treatments are always tried first with knee arthritis. These treatment options include:
- Activity modification: such as switching from high impact activities such as running to lower impact exercises such as swimming or biking, and lifestyle changes
- Anti-inflammatory medications
- Physical therapy: to help strengthen the muscles around the knee joint. Physical therapy programs in water (aquatic therapy) if available, allow patients to exercise in non-weight bearing situations.
- Injections: into the joint of either cortisone to help reduce inflammation and pain or visco supplements such as hyaluronic acid to help lubricate the joint may provide temporary relief for moderate to severe conditions.
- Neoprene sleeves and other dynamic braces to help support the knee joint
- Assistive devices such as a walker or a cane
If these non-operative treatments are unsuccessful in reducing pain and improving quality of life, surgery may be considered. These surgical options may include:
- Knee arthroscopy and debridement: although this will not cure the arthritis, it may be helpful in removing any loose pieces of bone or cartilage in the knee joint that are causing pain, swelling, or mechanical symptoms such as catching or locking
- Osteotomy: to correct malalignment of either the femur or the tibia. This is sometimes done if 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.
- Knee replacement: this may be a total knee replacement or a partial knee replacement depending on the severity and location of the arthritis.