The inflammatory arthritis diseases or spondyloarthropathies include various diseases such as Ankylosing spondylitis, the arthritis of bowel disease, reactive arthritis and the arthritis associated with psoriasis. The typical linking features of these diseases are enthesitis (an inflammation at the bone/ligament junction) and the presence of HLA B27, a gene on white blood cells. The inflammation at the entheses can develop into fibrosis and eventually to fusion of the joints from bone formation.

AS is the commonest of the spondyloarthropathies and its occurrence varies with the occurrence of the HLA B27 gene in the population, AS being less common in the tropics and more common in northern European countries. 0.1 to 1.0% of people are affected but this varies with latitude and is more common in white people. About 1-2% of people with the HLA B27 gene actually develop AS but this becomes 15-20% likelihood if they have a first degree relative with the disease.

Three males to every one female is the ratio of patients with Ankylosing spondylitis, as female patients may have much less obvious symptoms and so be missed from the diagnosis. Young men are the commonest presenting group with most consulting a doctor before they are 40 and up to 20% before they are sixteen years old. 25 years is the average age that someone goes down with the symptoms and is uncommon to find a diagnosis of AS in a person over fifty. It is easily overlooked as it can look like mechanical back pain if care is not taken. On questioning how they are in the morning, a typical answer is very stiff.

The presentation of Ankylosing spondylitis is similar but different from that of mechanical low back pain due to the inflammatory nature of AS:

Back pain and stiffness in the morning, lasting at least half an hour or more The back pain and stiffness are improved by exercising Resting worsens the stiffness and pain Pain is worse later in the night Thirty to fifty percent of patients exhibit other joint symptoms Fatigue is typical Systemic inflammatory affects include fever, loss of weight and unwellness.

Physiotherapy examination of the spine in an AS patient usually uncovers significantly reduced ranges of spinal movement from normal, with perhaps a reduced lumbar lordosis and an increased thoracic curve. Neck movements may also be limited in later stages and a reduction in chest expansion noted due to rib joint involvement. Peripheral symptoms occur in around a third of patients and the physio will palpate the tender areas, searching for evidence of enthesitis in the insertions of the Achilles tendon and plantar ligament of the foot. These are areas of high mechanical stress and commonly affected.

The physiotherapist initially notes the postural changes which have occurred in an AS patient such as any spinal deformities, round shoulders, bent knees or an increased cervico-thoracic curve and poking chin posture. The physio will record ranges of movement of the spine and include the neck, thorax and lumbar ranges, also assessing any peripheral joints which may be affected. Any entheses which are reported as painful are palpated to confirm the presence of an inflammatory process, and if the AS is very active then the physiotherapist might also find effusions in the joints, perhaps with a feeling of unwellness, night sweats and poor rest.

Physiotherapy starts with treating active enthesis sites with ice, ultrasound and gentle stretches, with insoles useful in the foot. Routine range of movement exercises for the whole spine and affected joints are taught with concentration on getting to end range at each time. This targets the antigravity movements such as lumbar and thoracic extension, thoracic rotations and neck rotation and retraction. Patients are also taught to rest in good positions to avoid encouraging the typical deformities, such as on a firm mattress with just one pillow, or lying on the front regularly. Hydrotherapy is a very helpful and popular way of maintain joint ranges and patients need to keep up self treatment over the long term.