Psoriatic Arthritis

Risk: Individuals with psoriasis are at greatest risk for developing psoriatic arthritis; approximately 5% to 8% of individuals with psoriasis develop psoriatic arthritis (Hammadi). In contrast to rheumatoid arthritis, which affects women more than men, psoriatic arthritis shows no gender preference. Psoriatic arthritis usually occurs in individuals between ages 35 and 55 years, but can develop at any age. Risk is greater among whites than other races. A family history of psoriatic arthritis is a risk factor for developing the disease.

Incidence and Prevalence: Incidence of psoriatic arthritis in the general population is estimated to be 1%; about 1 million adults in the US are affected (Hammadi) compared to 2 million with rheumatoid arthritis (Hammadi). Although incidence varies among countries, the incidence of psoriatic arthritis internationally ranges from 1% to 40% depending on the clinical criteria applied and whether all races are included (Van Voorhees). Prevalence is higher among whites than among African Americans and Native Americans; the disease occurs in 2.5% of white North Americans and 0.05% to 0.24% in the international white population (Hammadi).

History: The individual may describe a family history of psoriasis or psoriatic arthritis. The individual may complain of pain, stiffness, and swelling of the joints, especially the small joints of the hands and feet. Depending on the area affected by psoriatic arthritis, other complaints may include back pain, chest pain, pain on walking or climbing stairs, pain around the eyes, and shortness of breath. Humidity and temperature changes may affect arthritis symptoms. Fever may be present in patients with the arthritis mutilans subtype of psoriatic arthritis. Individual may report that psoriasis has been present for some time before arthritis symptoms or that psoriasis developed at the same time as arthritis symptoms. The physician will obtain a history of recent and prior illness, particularly bacterial or viral infections.

Physical exam: Psoriasis is usually present but may be limited to patches (lesions) between the buttocks, behind the ears, or other inconspicuous areas such as the umbilicus or scalp; psoriasis can be severe in some individuals. Swelling may be seen as well as deformity of the joints, especially finger joints in severe, chronic cases. Overgrowth of bone (hyperostosis) may be seen. "Sausage digits" (dactylitis) of the hands and feet are common in individuals with psoriatic arthritis. Affected joints often have a purplish discoloration. An accumulation of fluid may be seen in a joint (effusion). Nails of the affected digits may be pitted or crumbling (onycholysis). Inflammation of the outer membrane of the eyes (conjunctivitis) or the uveal tract (uveitis) may occur in up to 30% of individuals with psoriatic arthritis (Van Voorhees).

Tests: There is no specific diagnostic test for psoriatic arthritis; observing the pattern of joint involvement is essential to correct diagnosis. Blood tests that may be helpful in making the diagnosis include erythrocyte sedimentation rate and C-reactive protein to evaluate inflammation, hemoglobin, rheumatoid factor (to rule out rheumatoid arthritis), uric acid (to rule out gout), human leukocyte antigen (HLA) typing, and antinuclear antibodies. A sample of joint fluid may be analyzed to determine the number and type of white blood cells. A cytokine profile may be done to assess T cell and monocyte activation, which may help differentiate between psoriatic arthritis and rheumatoid arthritis. X-rays usually are done to help differentiate psoriatic arthritis from other types of arthritis based on degree of joint erosion. Depending on areas affected and symptoms reported by the individual, either CT or MRI imaging can be done to examine soft tissue and joint characteristics in more detail. CT scans of the sacroiliac joint are considered to be sensitive for viewing spondylitis or sacroiliitis. MRI is especially sensitive for assessing pathology of the hands and feet.

The goals of rehabilitation are to promote independence in all functional activities while protecting the involved joints. Because psoriatic arthritis is a progressive, systemic disease, individuals may benefit from a comprehensive rehabilitation program.

In conjunction with pharmacological management, rehabilitation focuses on stretching and strengthening the involved body parts. During an inflammatory period, care must be taken to protect the joints while preventing loss of motion and strength. Modalities such as heat and cold may be used (Braddom), and hydrotherapy is highly recommended, when available.

Rehabilitation should include general conditioning exercises that emphasize full range of motion and weight bearing exercises. This is especially important because loss of motion and osteoporosis are common in these individuals. Loss of motion results from changes within the joint, while osteoporosis may occur from prolonged use of steroids (Gladman, "Current Concepts").

Because this is a chronic condition, individuals should learn pain-control techniques (such as the use of heat, cold or relaxation) that they can perform at home. A lifetime program of walking, aquatic exercise, stretching exercises, and other physical fitness programs should be initiated prior to discharge from therapy. The therapist must instruct individuals in the importance of maintaining their level of fitness and independence while preventing joint damage.

Occupational therapy may also be necessary to address daily living activities. A home assessment might be indicated to ascertain that the environment is optimal for the individual's needs and to recommend assistive devices that might be helpful for common daily tasks.

An ergonomic evaluation may be beneficial to modify the work station so that individuals with psoriatic arthritis are able to maintain their employment status.

Because individuals may experience depression if their activities become restricted as the disease progresses, counseling or a support group might be needed.

Additional information may provide greater insight into the rehabilitation needs of this population (Gladman, "Assessment of Patients"; Veale).