Psoriasis is a relatively common disease of the skin and its treatment is not completely effective or particularly pleasant for patients. Even though an arthritic condition is known to be linked to psoriasis the diagnosis of arthritic disease may still be missed when a patient attends with joint signs and symptoms. Psoriatic arthritis can have multiple effects on the joints and can lead to permanent joint damage which can cause disability and effects on quality of life. The prevalence of this skin condition in the UK stands at around two percent, with about 14 percent of these suffering from some degree of joint signs.
In about fifteen percent of people suffering from these conditions the arthritic symptoms start before any skin lesions are apparent and in examination of people with psoriasis abnormalities in soft tissues have been found in the absence of joint symptoms. Psoriatic arthritis tends to affect a smaller number of joints that rheumatoid arthritis although there may be a similar pattern. In many cases only one or two joints may be involved. The attachments of the tendons and ligaments to the bones, areas called entheses, are typically involved. The largest such attachment in the body is that of the Achilles tendon to the heel bone and this area is often involved in inflammation and pain.
There are a large number of entheses in the body and these may be responsible for the more widely spread symptoms which can occur without joints being involved. There can be individual finger swelling with or without changes in other joints and this is a negative indication for disease progression. Back pain or inflammatory spondylitis can be similar to that of ankylosing spondylitis and the symptoms are worse with resting and better with exercising, significant stiffness in the early mornings, a slow and gradual onset and pain worse at night. About 30% of patients can have anatomical back changes without pain or problems and involvement of the nails and distal finger joints in the disease occurs also.
Diagnosing joint symptoms related to psoriasis can be difficult as the population ages and people complain routinely of more and more joint symptoms. The possibility of psoriatic arthritis should however always arise when a diagnostician is consulted by a person with psoriasis who complains of joint symptoms, with particular reference to back pain of possible inflammatory origin and involved distal finger joints. Typical blood tests which are raised in the presence of inflammation in the body are the ESR (erythrocyte sedimentation rate) and the CRP (C-reactive protein). If the joint picture is suspicious but no psoriasis is easily apparent it may be important to examine the patient carefully for hidden affected areas.
Approximately one third of patients with psoriatic arthritis have only a few joints affected and the disease is non-progressive which can be managed by controlling the symptoms and with occasional steroid injections into the affected joints. This group is important to identify early on so that more aggressive disease is not missed. Poor signs for the future of the joints are a large number of affected joints, being male, having taken steroids in the past and raised inflammatory blood tests. This group suffer gradual joint destructive arthritis and over a decade will develop a reduced quality of life due to the increasing disability.
The arthritic joint destruction can be rapid and quickly developing in a small number of sufferers which amount to around 5 percent. Cardio-vascular complications and metabolic syndrome occur at higher levels and identifying and controlling the risks, such as high blood pressure, being obese, smoking and cholesterol, is important. Referral to a rheumatologist should be made in any person with psoriatic skin lesions who presents with joint problems, although some may turn up with very local pain such as tennis elbow and others report widespread pain. Early referral ensures appropriate treatment and forestalls joint damage in the longer term.
A joint damaging and fast advancing arthritic disease is present in around 5% of sufferers from psoriatic arthritis. Cardiovascular disease and metabolic syndrome are more common and affect life expectancy so it is important to identify and control risks such as cholesterol, being overweight, hypertension and smoking. Patients should be referred to a rheumatologist if they have psoriasis and any features of joint problems, remembering that some patients present with pain which is widespread or conversely which is very local such a bilateral tennis elbow. Joint protection is best provided by early referral to prevent long term damage.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about
Physiotherapists, physiotherapy,
Physiotherapists in Exeter, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
