The knee is the largest joint in the body. A healthy knee moves easily, allowing you to walk, turn, and perform many activities without pain. A knee is flexible because of its complex structure of bones, cartilage, ligaments, muscles, and tendons working together.
The knee joint contains three bones: femur (thighbone) tibia (shinbone) and patella (kneecap). When you bend or straighten your knee, the rounded end of your thighbone rolls and glides across the relatively flat upper surface of your shinbone. The kneecap allows you to straighten your knee, providing leverage and reducing the strain on muscles within and around the knee joint.
In a healthy knee joint, the surfaces of these bones are quite smooth. They are covered with a tough protective soft tissue called cartilage.
Ligaments, another type of soft tissue, lie along the sides and back of the knee, holding the bones of the knee joint in place. These ligaments work with the muscles, bones and tendons so that you can bend and straighten your knee. Fluid-filled sacs, known as bursae, cushion the area where skin or tendons glide across bone. The knee also has a lining, or synovium, that secretes a clear liquid called synovial fluid. This fluid lubricates the joint and enhances elasticity, further reducing friction and making movement easier.
As you might expect, there are many different causes of knee pain, including injury, infection and arthritis. Arthritis is often the culprit. Two common types of arthritis are Osteoarthritis (OA) and Rheumatoid Arthritis (RA).
The most common cause of knee pain is osteoarthritis (OA), a degenerative joint disease that causes the cartilage in your joints to break down. When that layer of cartilage — which is meant to “cushion” the joints and protect the surface of the bones — is damaged or worn away, your bones grind against one another, causing pain. You may feel pain while climbing stairs, working in the garden, or just bending your knees to sit. This pain may even keep you up at night.
OA may damage the entire knee or it may be limited to one side of the joint. If you experience pain only on one side, or compartment, of your knee, your doctor may diagnose you with unicompartmental OA.
If you experience pain under the kneecap, your doctor may diagnose you with patellofemoral OA. This is not uncommon, as studies have shown that about one out of every 10 patients over the age of 40 has patellofemoral disease.
The factors leading to the development and progression of OA include aging, obesity, joint injuries, and a family history of arthritis (genetics). Although there is no cure, early diagnosis and treatment are crucial in slowing or preventing more damage to your joints.
In rheumatoid arthritis, the synovium (lining of the joint) becomes inflamed. This inflammation causes the release of chemicals that thicken the synovium and damage the cartilage and bone of the affected joint. Inflammation of the synovium causes pain and swelling.
Arthritis in the knee can be treated. Because arthritis may worsen over the years, it is common for treatment to involve more than one approach and to change over time. For some people, nonsurgical treatments such as lifestyle changes, medications and walking aids may help alleviate the pain. For others, replacing lost cartilage with tissue grafts can help restore normal function. And for many, knee replacement surgery may be the only long-term solution. Together, you and your doctor can determine the best treatment options for you.
Are you having difficulty performing daily tasks or staying active? Don’t let osteoarthritis slow you down. Find out how you can manage your knee pain and restore mobility.
If you have knee problems, a number of effective treatments available currently can provide significant relief. Whether your knee pain is moderate or severe, there are many options that can help you enjoy life without pain.
Pain: Intermittent pain and sharp or burning aches may signify the onset of OA. If the pain is constant, your OA could be worsening.
Stiffness: Joints may become difficult to move as a result of sitting, overusing joints, or following a long nap or night’s sleep.
Swelling: As fluid collects in the knee, joints may become tender and sore.
Deformed Joints: As osteoarthritis progresses, joints may appear misshapen or deformed.
Cracking and Creaking: OA frequently causes joints to make cracking or creaking noises and feel very rigid.
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