Osteoarthritis

Background

Osteoarthritis (OA) is a type of arthritis that mostly affects cartilage. This is the hard, slippery tissue that covers the ends of bones where they meet to form a joint. Healthy cartilage allows bones to glide over one another smoothly. It also absorbs energy that occurs from physical movement. For people who have OA, the surface layer of cartilage breaks and wears away. Bones under the cartilage then rub together, which can cause pain, swelling and loss of motion of the joint.

OA is the most common type of arthritis and is commonly seen among older adults. However, OA can also develop in younger people if they have had a joint injury, joint malformation or genetic defect in joint cartilage. Both men and women can develop OA. Before age 45, more men than women have OA; after age 45, it is more common in women. It is also more likely to develop in people who are overweight or who have jobs that stress particular joints.

People with OA usually experience joint pain and stiffness. The joints most commonly affected are those at the ends of fingers, thumbs, neck, lower back, knees and hips. It often affects people differently. In some people with OA, it may progress quickly. However, for most people with OA, joint damage develops gradually over the years. There are some people with OA who may have mild symptoms while it may cause a lot of pain and disability in other individuals.

An estimated 27 million Americans age 25 and older have OA. By 2030, an estimated 67 million people will have arthritis due to the aging population.

Causes

OA often develops slowly over time. Certain risk factors listed below can cause a person to develop OA:

  • Being overweight
  • Getting older
  • Joint injury
  • Joints that are not properly formed
  • A genetic defect in joint cartilage
  • Stresses on the joints from certain jobs or from playing sports

Symptoms

In the early stages of OA, a person’s joints may ache after physical work or exercise. As time goes by, joint stiffness may occur when a person first wakes up in the morning or has been in one position for a long time. The most common areas that are affected are the hands (mainly at the ends of the fingers and thumbs), spine (around the neck and lower back), knees and hips.

Hands
OA commonly causes small, bony knobs that appear on the end joints of the hands. These joints are closest to the nails of the fingers. This type of knob is called Heberden’s (HEBERR-denz) nodes. Another type of knob that can develop appears on the middle joints of the fingers. The fingers can become enlarged and twisted. This can cause the fingers to ache and become stiff and numb. This type of knob is called Bouchard’s (boo-SHARDZ) nodes.
Spine
If OA develops in the spine, it may show up as stiffness and pain in the neck or lower back. Sometimes this causes pressure on the nerves at the end of the spinal column. Weakness, tingling or numbness of the arms or legs may develop as a result. If a person has severe OA in the spine, it can affect how the bladder and bowel function.
Knees
One of the most common joints affected by OA is the knee. The knee may become stiff, swollen and be very painful. This can make it hard for a person to walk, climb and get in and out of chairs or bathtubs.
Hips
The most common site of OA is the hips. The joint may become very stiff and painful. Areas around the hip — such as the groin, inner thigh or buttocks — can also be painful. This can limit any moving or bending and make daily activities such as dressing or putting on shoes very difficult.

Diagnosis

No single test can be used to diagnose OA. A doctor will often use tests to help rule out other conditions that can cause the same symptoms of OA. The methods doctors often use to diagnose OA are:

Clinical history
A doctor will begin by asking the patient to describe their symptoms, when the symptoms started and if the symptoms have changed over time. The doctor will also ask about any other medical problems the patient may have and any family history of OA.
Physical exam
Reflexes, muscle strength and general health will be examined by the doctor. Any bothersome joints will also be checked, along with the patient’s ability to walk, bend and carry out activities of daily living.
X-rays
X-rays allow a doctor to determine the type of arthritis a person may have and the amount of damage that has been done to the joints. An x-ray of the affected joint can show if there is any cartilage that has been lost or any bone damage.
Magnetic resonance imaging (MRI)
An MRI test provides computerized images of internal body tissues. Doctors often use this test if they don’t see much damage on an x-ray and the patient is complaining of pain. This test can show any damage to joint tissues, such as a ligament or the pad of connective tissue in the knee known as the meniscus.
Other tests
A doctor will try to find out what is causing symptoms in a patient by ruling out other disorders with certain tests. Blood tests and a joint aspiration test can rule out other causes of symptoms. A joint aspiration test draws fluid from the joint through a needle to see if there is any bacteria that may be causing an infection or any uric acid crystals that can cause gout.

Treatment

Specialty drug list

The four goals of OA treatment are to control pain, improve joint function, maintain normal body weight and for the person to achieve a healthy lifestyle. The different treatment approaches include exercise, weight control, rest and relief from stress on the joints, pain relief techniques, medications to control pain and possibly surgery.

The following types of medications are commonly used to treat the pain experienced with OA:

Acetaminophen
This is the first medication a doctor will recommend to relieve pain because of its safety compared to other drugs and its ability to control pain.
Nonsteroidal anti-inflammatory drugs (NSAIDs)
This class of medications control pain and inflammation in OA. Each NSAID is a different chemical, so one NSAID may work better for someone than another. They are the most common treatment for arthritis. Examples of NSAIDs are aspirin, ibuprofen and naproxen.
Corticosteroids
The corticosteroids are injected into the affected joints to temporarily relieve pain. They are only used as a short-term treatment and are not recommended for more than two to four treatments per year.
Hyaluronic acid substitutes
This class of drug treatments are used to replace a normal component of the joint that helps with joint lubrication and nutrition. They are approved only for OA of the knee and are often given in a series of three to five injections.

Side Effects

Treatment can cause side effects, but it is important that a person never change their dosage or stop taking their medication. A doctor or pharmacist should be informed if bothersome side effects are occurring. Common side effects for the different treatment options for OA include:

Acetaminophen
Nausea, vomiting, heartburn, diarrhea and headache
NSAIDs
Nausea, vomiting, heartburn, diarrhea and headache
Corticosteroids
Weight gain, increased appetite, anxiety, nervousness and increased risk of developing an infection
Hyaluronic acid substitutes
Pain at the site of injection, knee swelling and headache

Resources

There are many resources and organizations available to help, providing support, advocacy and information:

Arthritis Foundation

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

References

Centers for Disease Control and Prevention. http://www.cdc.gov/arthritis/basics/osteoarthritis.htm. Accessed December 27, 2011.

National Institutes of Health. NIAMS. Handout on Osteoarthritis. NIH Publication No. 10-4617. July 2010.