There are three kinds of arthritis that can affect the knee: osteoarthritis, inflammatory arthritis, and post-traumatic arthritis. Osteoarthritis (OA) is the most common type of arthritis to affect the knee. It is estimated that 85 percent of osteoarthritis originates from changes that are part of the normal aging process (just like gray hairs and wrinkles). The remainder occurs from post-traumatic osteoarthritis (PTOA), which occurs after a knee injury such as an ACL tear or meniscus injury that predisposes the knee to future joint degeneration. It is important to differentiate osteoarthritis (wear and tear changes of the joint) from inflammatory conditions like rheumatoid arthritis, which is an autoimmune disease (where your body attacks its own joints). In autoimmune diseases, the immune system malfunctions and attacks the body instead of intruders. In the case of rheumatoid arthritis, it attacks the synovial membrane that encases and protects the joints, often affecting several joints at one time. Knee OA makes it difficult to perform many daily activities. These include kneeling, climbing stairs, and even walking.
Osteoarthritis affects over fifty million adults in the United States and is the most prevalent musculoskeletal disease. Worldwide, it is estimated that knee osteoarthritis affects 3 percent of the population, or approximately two hundred million people. Osteoarthritis has been reported to account for up to 18 percent of all health care visits and is associated with numerous other health issues, including increased rates of depression and other conditions such as diabetes, obesity, and heart disease. Economically speaking, osteoarthritis is the biggest contributor to work loss each year, costing the US economy roughly $100 billion per year. For comparison, health care costs from osteoarthritis constitute twice the costs devoted to chronic heart and lung disease.
What is osteoarthritis of the knee?
Osteoarthritis (OA) is a chronic, progressive, degenerative disease. It is often called “wear and tear” arthritis, because it is the slow deterioration of cartilage, causing the bones to rub against each other. It can affect the shin bone (tibia), the thighbone (femur), and the kneecap (patella).
Does the loss of cartilage hurts?
Cartilage does not have nerves and therefore does not cause pain when damaged. However, irritation of the bone beneath the cartilage or the linning the joint (synovial) that results from cartilage loss can cause pain. Some people have significant OA, but they might not have pain. Therefore, it is important to understand that sometimes we only need to take care of the symptoms as that might be all a patient needs.
What causes OA?
OA is a disease of aging, generally affecting people over the age of 50. OA tends to run in families and women are more often affected than men. Excess weight puts extra pressure on the knee joint, with every pound of weight adding 3-4 pounds of extra weight transmitted across your knees. Additionally, if you are bowed legged (misaligned) or put repetitive stresses on the joint, either due to work or athletic endeavors, this can increase the risk of developing OA. Previous traumatic injuries to the knee can also result in post-traumatic OA.
What are the symptoms of knee OA?
The primary symptoms are pain, swelling and stiffness. OA is characterized by a gradual increase in pain as the cartilage is slowly worn away. Symptoms also depend on the location of the osteoarthritis.
- Pain in the morning
- Stiffness, swelling and pain with long periods of inactivity
- Pain climbing stairs
- Pain with walking
- Pain when standing up or sitting down
- Pain that interferes with sleep
Other symptoms may include:
- Swelling and tenderness due to periodic inflammation caused by the formation of bone spurs or excess fluid in the knee.
- A grinding sensation within using the knees, as a result of bone spurs and wearing of the ends of the bones. Clicking and crackling sounds as the cartilage frays, and the protective space between the bones decreases.
- Locking or catching of the knee from loose bodies or fragments of cartilage that interfere with movement.
- Reduced range of motion.
- Gradual weakening of the knee muscles cause instability in the joint.
- Deformity of the joint.
How is OA diagnosed?
In addition to a review of your medical history and symptoms, renowned orthopedic surgeon Dr. Jorge Chahla will conduct a physical exam, including range of motion testing. Dr. Chahla will also ask you questions about what causes your pain. He will also order x-rays which will show the space between the bones of the knee joint, which if narrowed, indicates OA. Since articular cartilage cannot be seen on x-ray, it is seen as a space – the less space, the less cartilage. Other imaging tests may be ordered if there is an indication of tissue damage. Blood tests can be ordered to rule out inflammatory arthritis which is an autoimmune disorder if multiple joints are affected at the same time (not very common).
Is there a cure for OA?
Currently, there is no true cure for osteoarthritis as we cannot regenerate cartilage. Only the symptoms can be treated. Injections (cortisone, hyaluronic acid [gel injections], platelet rich plasma (PRP), or stem cells) can provide temporary pain relief by diminishing inflammation and improving lubrication in the joint when a total joint replacement is not yet indicated. The optimal time to get these injections depends completely on your symptoms. If you are suffering from pain, and it’s limiting your activities to a point where you feel that you cannot do things you would like to do, it is the right time to look into these options. Sometimes waiting can lead to further muscular atrophy (weakening) as a result of inactivity, with subsequent worsening of the symptoms. As sports medicine doctors, the goal is to keep patients active to perform the activities they would like to do.
What can my doctor do for me?
Arthritis of the knee can be managed with anti-inflammatory medication, injections including cortisone, viscosupplementation (also known as hyaluronic acid), and platelet rich plasma (PRP) injections. Bracing and physical therapy can also play a role. When conservative treatment fails, a partial or complete joint replacement are an option to treat arthritis pain.
Chicago’s renowned orthopedic surgeon Dr. Jorge Chahla strives to provide the best orthopedic care available to restore your natural range of motion and quality of life.
At a Glance
Dr. Jorge Chahla
- Triple fellowship-trained sports medicine surgeon
- Performs over 500 surgeries per year
- Assistant professor of orthopedic surgery at Rush University
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