Knee Osteoarthritis

Knee osteoarthritis is the most common form of osteoarthritis. More than 10 million Americans have knee osteoarthritis. It is also the most common cause of musculoskeletal disability in the United States. Successful management of knee osteoarthritis depends on recognizing early symptoms, an accurate diagnosis, and appropriate treatment.

Signs and Symptoms of Knee Osteoarthritis

Knee osteoarthritis is typically characterized by the insidious onset of joint pain, joint stiffness, and limited range of motion. Unknowingly, knee osteoarthritis develops gradually over a period of years and goes unnoticed until it becomes symptomatic. It is common for people with knee osteoarthritis to initially complain of pain that occurs with walking, plus limitations with walking (e.g., distance), going from sit to stand, and stair-climbing. Other common complaints include a feeling that the knee is going to give out, the affected knee locks up, or a popping sensation in the joint. There is often localized swelling, but it is usually not associated with warmth or redness. With any of the aforementioned signs and symptoms, after a brief period of time to see if symptoms subside or if self-treatment helps, most people realize that they must consult their doctor for a proper diagnostic evaluation.

Pain associated with knee osteoarthritis is usually worse following activity, especially when there is overuse of the affected knee. Stiffness can worsen after sitting for prolonged periods of time. As knee osteoarthritis progresses, symptoms generally become more severe. Pain may become constant, rather than present only when weight-bearing or following activity.

Bone cartilage breaks down with osteoarthritis.

Constant and severe pain is characteristic of bone-on-bone abnormalities which occur when cartilage loss is so severe there is essentially no cartilage left covering the ends of the bones in the knee joint. Loose bodies in the joint space may also contribute to pain and stiffness. Crepitus (a grinding sensation) and an increase in symptom intensity that occurs with stormy weather are also characteristic of knee osteoarthritis—although the latter has been debated.

Deterioration of articular (joint) cartilage, which is evident on plain x-rays, is an important diagnostic clue associated with knee osteoarthritis. The cartilage loss in knee osteoarthritis can be caused by:

  • previous knee injury
  • repetitive strain on the knee
  • fracture, ligament tear, and meniscal injury, any of which can affect the alignment of the knee and leg, further promoting wear and tear
  • genetic predisposition to cartilage abnormalities and knee osteoarthritis
  • obesity and overweight which add stress and burden to the affected joint; adipose tissue increases proinflammatory cytokines; and leptin may play a role
  • problems with subchondral bone (the bone layer underneath the cartilage in the knee)

Diagnosis of Knee Osteoarthritis

As is the case when any type of arthritis is suspected, the initial consultation with your doctor begins with a discussion of the symptoms that you have been experiencing. A review of your medical history and a physical examination follow. You should expect diagnostic tests to be ordered, too—blood tests to rule out other types of arthritis and x-rays to look for evidence of joint damage.

During the physical examination, your doctor will observe the affected knee for swelling, redness, warmth, and deformity (e.g., varus versus valgus deformity). Your doctor will assess range of motion passively and actively, and note if there is tenderness to the touch. Your doctor will observe your gait, as well as signs of increased pain with weightbearing. With osteoarthritis, usually one knee is affected more than the other, but both may be affected, typically at different times.

Imaging studies are needed to look for evidence of structural changes consistent with osteoarthritis and to rule out other conditions. Plain x-rays are ordered first and if more detailed imaging is needed, an MRI or CT scan may be ordered. Arthroscopic knee surgery is another way to view the condition of the knee.

The examination and imaging studies will reveal which component of the knee is affected. The patellofemoral joint and medial tibiofemoral joint are most often affected by osteoarthritis. The lateral tibiofemoral joint is less commonly affected by osteoarthritis. As you might expect, the location of pain offers a good indication of which knee component is involved. Pain in the patellofemoral joint is usually made worse by a long period of sitting, standing up from a low chair, climbing stairs, or coming down an incline. Anterior knee pain that radiates distally may be consistent with moderate to severe knee osteoarthritis. Knee pain associated with sleep disruption is usually indicative of advanced osteoarthritis. There is usually no pain posterior to the knee unless associated with a Baker's cyst.

Treatment for Knee Osteoarthritis

Knee osteoarthritis cannot be cured, but there are treatments available to help manage the symptoms. There are pharmacologic and non-pharmacologic treatment options.

Over-the-counter medications, such as acetaminophen, can help with pain relief. Some patients obtain better pain relief from taking one of the NSAIDs (nonsteroidal anti-inflammatory drugs) or Celebrex (celecoxib), the one remaining COX-2 selective inhibitor that is still marketed in the U.S. There are also opioid analgesic medications available for patients who need stronger pain relief.

Besides oral medications, other treatment options for knee osteoarthritis include local intra-articular injections of steroids or viscosupplements. Steroid injections are used to quickly relieve pain and inflammation. Viscosupplements, or hyalruonates, are gel-like substances which can be injected into the affected knee with the intent of providing lubrication and cushioning, similar to properties of synovial fluid in a normal joint.

There are several "common sense" ways to manage knee osteoarthritis:

A Word From Verywell

About 13 percent of women and 10 percent of men 60 years old and older have symptomatic knee osteoarthritis. While the incidence of knee osteoarthritis increases with age, anyone can develop the disease.

Depending on disease severity, knee osteoarthritis can impose significant physical limitations and functional limitations, and consequently, greatly impact quality of life. You may be surprised to learn that osteoarthritis is also associated with a higher risk of mortality compared to the general population. With a history of diabetes, cancer, or cardiovascular and the presence of walking disability, there is increased risk.

Gaining control of knee osteoarthritis requires that you recognize early symptoms, consult your doctor to obtain an accurate diagnosis, stick with a regimen consisting of proven and effective treatment options, and pay strict attention to modifiable factors that may affect disease progression. Verywell is happy to provide you with the information you need to have a basic understanding of knee osteoarthritis, an understanding of your doctor's recommendations, and the latest guidelines for managing knee osteoarthritis.

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