Osteoarthritis Health Article

Definition

Osteoarthritis (OA) is a progressive disorder of the joints caused by gradual loss of cartilage that may result in the development of bony spurs and cysts at the margins of the joints. The name osteoarthritis comes from three Greek words meaning bone, joint, and inflammation.

Description

OA is one of the most common causes of disability due to limitations of joint movement, particularly in people over the age of 50. It is estimated that 2% of the United States population under the age of 45 also suffers from osteoarthritis; this figure rises to 30% in persons between the ages of 45 and 64, and 63–80% in those over age 70. Approximately 90% of the American population will have some features of OA in their weight-bearing joints by age 40. Men tend to develop OA at earlier ages than women.

OA typically develops gradually, over a period of years. Patients with OA may have joint pain on only one side of the body. It primarily affects the knees, hands, hips, feet, and spine.

Causes and symptoms

Osteoarthritis results from deterioration or destruction of the cartilage that normally acts as a protective cushion between bones, particularly in weight-bearing joints such as the knees and hips. As the cartilage is worn away, the bones may form spurs, areas of abnormal hardening, and fluid-filled pockets in the marrow. These are known as subchondral cysts. As the disorder progresses, pain results from deformation of the bones and fluid accumulation in the joints. Pain may be relieved by rest, but worsened by placing weight on, or moving, the joint. In the early stages of OA, the pain is minor and may take the form of mild stiffness in the morning. In the later stages of OA, inflammation develops; the patient may experience pain even when the joint is not being used; and he or she may suffer permanent loss of the normal range of motion in that joint.

Osteoarthritis typically has been considered by laypeople as an inevitable part of aging caused by simple wear and tear on the joints. This view has been replaced by recent research into cartilage formation and preservation. Osteoarthritis is now considered to be the end result of several different factors that can contribute to cartilage damage, and is classified as either primary or secondary.

Primary osteoarthritis

Primary OA results from abnormal stress on weight-bearing joints, or normal stress affecting weakened joints. Primary OA most frequently affects the finger joints, the hips and knees, the cervical and lumbar spine, and the big toe. Some gene mutations appear to be associated with OA. Obesity also increases the pressure on the weight-bearing joints of the body. Finally, as the body ages, there is a reduction in the ability of cartilage to repair itself. In addition to these factors, some researchers have theorized that primary OA may be triggered by enzyme disturbances, bone disease, or liver dysfunction.

Secondary osteoarthritis

Secondary OA results from chronic or sudden injury to a joint. It can occur in any joint. Secondary OA is associated with the following factors:

• trauma to the body, including sports injuries
• repetitive stress injuries associated with certain occupations (i.e., the performing arts, construction or assembly line work, computer keyboard operation, etc.)
• repeated episodes of gout or septic arthritis
• poor posture or bone alignment caused by developmental abnormalities
• metabolic disorders

Diagnosis

The two most important diagnostic clues in the patient's history are the pattern of joint involvement and the presence or absence of fever, rash, or other symptoms outside the joints.

History and physical examination

When taking vital signs (i.e., blood pressure, weight, temperature), the patient's gait and arm and hand movement should be observed by the nursing staff or physician assistants; if pain is the chief complaint, the affected joint should be examined. After a brief examination, the nurse, nurse practitioner, or physician assistant should ask the length of time the pain has affected the patient and if there have been any limitations in his or her work or home life. The practitioner should record abnormal symptoms on the intake sheet for review by the physician. As part of the physical examination, the physician will evaluate swelling, limitations on the range of motion, pain on movement, and crepitus (i.e., cracking or grinding sound heard during joint movement). Osteoarthritis is often similar in presentation to rheumatoid arthritis, but lacks the presence of inflammation (until its very late stages) found in rheumatoid arthritis.