Ankylosing Spondylitis
Ankylosing Spondylitis (AS) is a progressive inflammatory disease. Although it principally affects the spine, usually commencing in the lower back, it can also affect other joints, tendons, and bodily systems. Eye and heart involvement are the commonest non-articular features. Inflammatory bowel disease (Crohn’s disease and Ulcerative Colitis) affect approximately 1 in 12 people with AS.
AS is commoner in men than women (2.5:1).
Genetic factors are associated with the development of AS, and the basic abnormality is an inflammation of the ligament and tendon junctions with the skeleton. This is called enthesitis. These are infiltrated with Lymphocytes and go on to heal with outgrowths of bone, which meet arising from the vertebra above and the vertebra below. On meeting, the bones ‘fuse’ together and cause rigidity of the spine.
The typical presentation of AS is in a young man of late teens or early 20’s. (Onset of the disease is rare over 40 years of age).
Clinical Findings
The main clinical findings are:
- insidious onset of episodic low back pain and stiffness, gradually worsening in both intensity and duration.
- Pain and stiffness of low back typically worse in the morning and after resting. Relieved by exercise and activity.
- Tenderness of one or both sacroiliac joints on palpation.
- Stiffness of lumbo-sacral spine, gradually spreading up the spine taking several years, until the whole spine may be affected.
- Reduced movement of spine in all directions.
- Involvement of peripheral large joints (hip, shoulder, elbow) often asymmetrical, usually in established disease, with reduced chest expansion.
Symptoms
The main symptoms of AS are low back pain, radiating to one or both buttocks and/or posterior thighs, together with stiffness causing progressive loss of spinal movement. Sacroiliac joint involvement is the hallmark of the disease. The symptoms are worse in the morning and after resting, and relieved by exercise. Fatigue is a very important symptom and is a reliable marker of disease activity. In active disease, fatigue increases the disabling effects of AS.
Symptoms of AS may be mild initially, and then worsen as the disease progresses. During disease progression, increasing stiffness of the spine occurs with reduced spinal movement in all directions. Untreated, the spine fuses in a flexed or bent posture causing marked disability. Such cases are now uncommon due to active treatment.
Clinical Features
Peripheral joints, such as the shoulders, hips, and feet may be affected. The younger the age of onset, the more likely the hip will be involved. Hip involvement leads to fixed flexion deformities, where it is not possible to straighten the hip thus adversely affecting posture and gait. Due to restriction of hip movement help may be needed with putting on shoes and socks. Rarely, the joints of the hands can also be affected.
AS does not only affect joints. The disease is systemic, causing fatigue and other disorders. Eye problems (Acute anterior uveitis) occur in 25% of cases. This presents with eye pain, photophobia and blurred vision. Interaction between the systemic complications of AS (e.g. Crohn’s disease, anaemia, frequent eye disease, Reiter’s syndrome and colitis) will greatly increase the disabling effects of AS.
Breathlessness on exertion may occur in severe cases due to reduced chest expansion as a result of fusion of the joints between the ribs and the spine (costovertebral joints). The earlier the chest is involved in the disease the greater will be the reduction of chest expansion.
Chest pain may result from inflammation of the joints between the ribs and the sternum (costochondritis). This produces pain at the front of the chest. The combination of costovertebral and costochondral joint involvement can cause pain all around the chest. Enthesitis can affect the intercostal muscles in between the ribs and this causes pain in between the ribs.
Less common but very significant, are heart problems affecting the aortic valve in about 10% of cases.
Unless AS is severe or peripheral joint and/or neck involvement is present, most patients are able to lead an active life, and remain in employment. Around 75% will be in this category and enjoy a good quality of life. The remainder, however, may be severely disabled.
Even if severe ankylosis occurs, where the entire spine is fused, functional limitation may be minimal as long as the spine is fused in an erect position. Due to back stiffness however, help may be required with lower garments when dressing, and with getting in and out of the bath.
If the hips are involved, or severe neck involvement is present, the functional prognosis is much worse.
Preserving hip movement, especially extension is the key to maintaining functional independence in AS. If the hips move normally, it is possible to function very well, even with a stiff spine. Individuals may be able to touch the floor bending at the hips, if hip function is good, and changes in lifestyle are likely to be minimal.
The effects of Fatigue must be taken into account when assessing the disabling effects of AS.
Although neck involvement is fairly common in AS, in advanced or severe cases the neck (cervical spine) may rarely become fused in a flexed position making forward vision difficult. Neurological involvement affecting the upper limbs may also occur, causing weakness and loss of grip.
Summary
As stated above, the majority of affected individuals do well with minimal disability or being fully independent. However, occasionally the course of AS is severe and rapidly progressive, resulting in extensive incapacitating deformities.
Treatment
The key to effective control of AS is early diagnosis, and a programme of preventative exercises and activity designed to keep the spine as mobile as possible for as long as possible. Chest expansion is also encouraged. Occupational Therapy is vital to analyse each individual’s activity and lifestyle, and agree a planned course of activities to maintain independence and decrease pain and fatigue.
It is essential that this programme of exercise, education and lifestyle management is commenced (and continued with) before the ankylosing process of spinal fusion has started. Eventually the spine will fuse, even with therapy, but disability is likely to be minimal if the spine can be allowed to fuse in the erect or upright position.
The outcome of AS is variable. A proportion of patients develop an irreversible forward bending (kyphosis) of the spine, with marked disability. Rheumatologists are unable to predict which patients will develop spinal fusion and do badly.
When the inflammation of AS is active, morning pain and stiffness may be too severe to permit active and effective exercise. In this situation, pain control and reduction of inflammation and fatigue with Non Steroidal Anti Inflammatory Drugs (NSAIDS) may help exercise compliance and engagement in daily activities.
Newer therapies such as Disease Modifying Anti Rheumatic Drugs (DMARDs) and Biological Agents may also be used in moderate or severe disease. They may be useful for alleviation of symptoms but there is no current evidence that they have any effect on disease progression.
Injections of steroids into peripheral joints or structures may also be needed to reduce inflammation and increase function.
Wrist and/or finger splints are sometimes required if the hands are involved.
Surgery may be required where there is severe hip knee or shoulder restriction. Hip surgery may be particularly helpful in restoring functional independence, and reducing the need for difficult spinal surgery. However, very occasionally, spinal surgery may be required in cases of severe curvature of the spine.
Amended December 2011
