An Overview of Knee Osteoarthritis

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Knee osteoarthritis is the most common form of osteoarthritis. It results from the degeneration of cartilage in the knee, which can happen due to aging, carrying excess weight, and injury, among other things. The disease process begins before symptoms, pain, stiffness, and motion restriction, are noticed. Because of this and the fact that knee osteoarthritis is a progressive disease, getting a diagnosis and proper treatment as early as possible is key.

More than 14 million Americans have knee osteoarthritis. It is the most common cause of musculoskeletal disability in the United States. About 13% of women and 10% of men 60 years of age and older have symptomatic knee osteoarthritis. While the incidence of knee osteoarthritis increases with age, anyone can develop the disease.

Older woman suffering from pain in knees at home. Holding her knee and massaging with hands, feeling exhausted, sitting on sofa in living room. Close-up. Medications and pills on table
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Symptoms

Knee osteoarthritis is typically characterized by the insidious onset of its common symptoms:

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.

As knee osteoarthritis progresses, symptoms generally become more severe. Pain may become constant, rather than present only when weight-bearing or following activity. Crepitus (a grinding sensation) may be more noticeable with advanced osteoarthritis; visible joint deformity may also occur.

With osteoarthritis, usually one knee is affected more than the other, but both may be affected, typically at different times. The patellofemoral joint (at the front of the knee) and medial tibiofemoral joint (inner side of knee) are most often involved. The lateral tibiofemoral joint (outer side of the knee) is less commonly so.

Causes

Knee osteoarthritis is caused by the breakdown of cartilage, the protective tissue that allows joint bones to glide over each other. Eventually, the cartilage loss may be so severe there is essentially none left covering the ends of the bones in the knee joint (known as a bone-on-bone abnormality). Loose bodies in the joint space may also contribute to pain and stiffness.

The cartilage loss in knee osteoarthritis can be caused by:

  • Age ("wear-and-tear" causes cartilage breakdown)
  • The previous knee injury, which may include fracture, ligament tear, and meniscal injury: These can affect the alignment of the knee and leg, further promoting wear and tear.
  • Repetitive strain on the knee
  • Genetic predisposition to cartilage abnormalities and knee osteoarthritis
  • Obesity and overweight, which add stress and burden to the affected joint; adipose tissue increases pro-inflammatory cytokines; leptin may also play a role
  • Problems with the subchondral bone (the bone layer underneath the cartilage in the knee)

Diagnosis

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. The location of the pain and when it occurs will assist in the diagnosis of knee osteoarthritis:

  • Pain at the front of the knee (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.
  • There is usually no pain posterior to the knee unless associated with a Baker's cyst.
  • Knee pain may disrupt your sleep (advanced cases)

A review of your medical history and a physical examination follow. Your doctor will:

  • Observe the affected knee for swelling, warmth, and deformity, which may point to osteoarthritis or other conditions
  • Assess range of motion passively and actively
  • Note if there is tenderness to the touch
  • Observe your gait, as well as signs of increased pain with weight-bearing

You should also expect blood tests to rule out other types of arthritis and imaging studies to look for evidence of structural changes consistent with osteoarthritis and for the purposes of differential diagnosis. X-rays are ordered first and if more detailed imaging is needed, magnetic resonance imaging (MRI) or a computed tomography (CT) scan may be ordered. The condition of the knee might also be viewed during arthroscopic knee surgery.

The examination and imaging studies will reveal which component of the knee is affected.

Treatment

Knee osteoarthritis cannot be cured, but there are treatments available to help manage the symptoms.

Over-the-counter medications, such as Tylenol (acetaminophen) or Advil (ibuprofen) can help with pain relief. Topical creams (non-prescription) are an option for pain relief.

Some patients obtain better pain relief from taking prescription medication. This might be one of the prescription nonsteroidal anti-inflammatory drugs (NSAIDs) 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.

Prescription Voltaren (diclofenac) gel is a topical NSAID that gives a non-oral medication alternative.

Other treatment options for knee osteoarthritis include local intra-articular injections of steroids (which quickly relieve pain and inflammation) or viscosupplements (which provide lubrication and cushioning to the joint).


Knee replacement surgery is used as last resort after conservative treatments have failed to produce an adequate response.

Coping

Depending on disease severity, knee osteoarthritis can impose significant physical limitations and functional limitations, and consequently, greatly impact the quality of life. There are several lifestyle changes and home remedies helpful in managing knee osteoarthritis:

  • Exercise/physical activity/physical therapy: Movement and activity are essential for improving and preserving strength and range of motion.
  • Maintaining a healthy weight: Extra pounds add stress to your knee.
  • Knee brace or support: Wearing a knee brace provides stability and pain relief.
  • Heat and cold therapy: Application can help relieve pain and inflammation.

A Word From Verywell

Gaining control of knee osteoarthritis requires that you recognize early symptoms and consult your doctor to obtain an accurate diagnosis. Once diagnosed, stick with a regimen consisting of proven and effective treatment options. Protect your joints by paying strict attention to modifiable factors that may affect disease progression.

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