Ankylosing Spondylitis (AS) is an inflammatory arthritis that affects the joints of the back (particularly the SIJ’s), neck, ribs, and sternum. It can also affect the large peripheral joints, particularly the shoulders, hips, knees & ankles. It affects approximately 0.5% of the population, or around 100,000 Australians. Typical symptoms include morning stiffness of 30 minutes or longer, night pain, alternating buttock pain, & painful swelling of joints. There may also be associated diarrhoea, soreness of the eyes & blurred vision. The condition has an insidious onset, & the pain is improved by exercise but not by rest. AS affects people between the ages of 15 & 40, and males 3 times more than females. It tends to run in families, particularly those that carry the gene HLA-B27.
While AS is chronic & progressive, the disease process is highly variable. Most patients suffer episodic flare-ups of spinal pain, & a slow deterioration in spinal mobility. There may be associated joint deformity. Up to 25% of the AS population will develop substantial disability & restriction due to widespread fusion of the spine – the typical ‘bamboo spine’. Interestingly, much of the pain & stiffness felt by the patient is due to soft tissue inflammation, particularly at bony entheses.
Further investigation is warranted in any patient under 40 years of age presenting with chronic back pain of 3 months or longer, & referral to a rheumatologist is recommended. In AS, an early & accurate diagnosis is important, and the disease is very treatable. Delay in treatment may lead to joint destruction & immobility. Unfortunately, many people with AS have symptoms for years before the diagnosis is made. In 5% of patients with chronic LBP, the pain is due to some form of inflammatory condition. 60% of patients with inflammatory back pain will go on to develop sacroiliitis within 10 years. This confirms the diagnosis of AS. While the SIJ’s are the most common joint to show early signs of the disease, sometimes the thoracic or other spinal joints will be involved without pelvic joint involvement. MRI is a useful imaging tool to demonstrate inflammatory changes in the SIJ’s.
Pharmaceutical treatment: in the last 10 years there have been great advances in drug therapy for AS, particularly utilizing the tumour necrosis factor inhibitors. They help to suppress the inflammation & greatly reduce symptoms. However they do not appear to modify the course of the disease. Because patients have reduced pain with these medications, they often do not see the need to exercise. It is therefore important to ensure they maintain their exercise programme while being medicated. TNF inhibitors are available under the PBS only for people with established & active disease. To qualify for this medication, it is a requirement to undertake & diarise a 3 month exercise programme. This is the time when the patient should see a physiotherapist, to assess, measure & individualise an exercise programme.
Signs on physiotherapy examination may include a stiff flat lumbar spine, & loss of reversal of the lordosis on forward flexion. Muscles & ligaments lose their extensibility, and this may be detected on manual palpation. Patients will also develop neck protrusion & increased thoracic kyphosis, protracted shoulders, & subsequent decrease in height. Pelvic involvement leads to hip flexor tightness, & reduced hip internal rotation & abduction ranges.
Exercises are very important, to help in the maintenance of flexibility. Programmes need to be individualised to the patient’s specific needs. As stated above, many of the symptoms of AS arise from soft tissue inflammation. This soft tissue related stiffness is very responsive to exercise. Physiotherapy approaches include education about exercises, pain relief strategies, postural maintenance, maintaining chest expansion, improving muscle strength, & increasing exercise tolerance & general fitness. Specific techniques of heat, electrotherapy, assisted stretching, massage (including trigger point techniques) & joint mobilisation can also be very effective. Due to loss of lumbar flexion mobility, maintenance of forward flexion is very important in the early stages. Postural correction & stretching will also address the thoracic kyphosis & rounding of the neck & shoulders. The younger the age of onset of the disease, the more likely the hip joints will be affected. Correction of faulty biomechanics, & maintenance of flexibility in the hips is particularly important, as faults here will lead to problems throughout the lower limb kinetic chain.