Chapter 19 Ankylosing spondylitis and the seronegative spondyloarthopathies

Mark L. Clemence, MPhil Grad Dip Phys MCSP, Physiotherapy Department, Torbay Hospital, Torquay, UK

INTRODUCTION

This chapter will describe the group of disorders collectively known as the spondyloarthropathies a group of interrelated but heterogenous conditions (Boonen et al 2004). The treatment of these conditions will be considered using ankylosing spondylitis (AS) as the exemplar. A number of different terms have been used to describe the same group of conditions including spondarthritides (Moll 1987), spondylarthropathies (Hakim & Clunie 2002), seronegative spondlyloarthritides (Olivieri et al 2002) and spondyloarthropathies (Wordsworth 2002). The last term has been adopted for use in this chapter. The chapter will cover ankylosing spondylitis, psoriatic arthritis, reactive arthritis and Reiter’s disease, and enteropathic arthritis.

There is a degree of disagreement over the grouping and classification of the conditions within the group collectively known as the spondyloarthopathies (SpA) (Nash et al 2005). It was once thought that different entities of the SpA group represent variable expressions of the major characteristics of the same disease. Patients with SpA commonly test negative for rheumatoid factor hence the term ‘seronegative’. In addition there is a common but variable association with the genetic factor HLA-B27, although some evidence suggests that there are also close associations with other HLA gene factors in this group (Said-Nahal et al 2002). There are racial variations in HLA B27 distribution with corresponding variations in the prevalence of SpA within the same racial grouping. Box 19.1 lists the common features associated with the SpA group of conditions.

ANKYLOSING SPONDYLITIS

Ankylosing spondylitis (AS) is an inflammatory disease that affects the axial skeleton causing characteristic inflammatory back pain, which can lead to structural and functional impairments and a decrease in quality of life (Braun & Sieper 2007). Fibrosis and ossification of ligament, tendon and capsule insertion (the entheses) mainly in the regions of the intervertebral discs and sacroiliac joints are hallmarks of the condition (Hakim & Clunie 2002). Inflammatory changes can also occur in the cartilagenous joints of the axial skeleton (symphysis pubis, discovertebral junction and manubrio sternal joint). The disease can sometimes affect the hip joints.

Initial changes usually begin in the sacroiliac joints, lumbosacral and thoracolumbar joints with later change progressing throughout the axial skeleton. The inflammatory process results in ligament ossification and the formation of vertical outgrowths of bone called syndesmophytes. Progressive syndesmophye growth results in bony union between adjacent vertebrae. In moderate and severe cases there is progressive and irreversible stiffening of the vertebral column (Fig. 19.1). The disease has an insidious onset and typically continues over many years. Left untreated it will usually result in severe spinal deformity and functional limitation.

Figure 19.1 Anterior-posterior view of the sacroiliac joints in long-standing ankylosing spondylitis shows total ankylosis. Ossification of the ligaments connecting the posterior superior aspect of the sacroiliac joints is evident (arrows).

From Hochberg MC et al (2008) Fig. 108.6, with permission.

There is lack of universal agreement over the current classification system for AS (Braun et al 2002). A range of diagnostic criteria have been developed although in the early stages of the disease a person might be diagnosed as having AS without fulfilling all the criteria. The following is a description of the Modified New York criteria (Van der Linden et al 1984):

• Low back pain of at least 3 months duration with inflammatory characteristics

• Limitation of lumbar spine movement in saggital and frontal planes

• Reduced chest expansion (relative to normal for sex and age)

• Bilateral sacroiliitis grade 2 or higher on x-ray

• Unilateral sacroiliitis grade 3 or higher on x-ray.

Definite ankylosing spondylitis is said to be present when the 4^th or 5^th criteria is present with one of the clinical criteria (1–3), probable AS can be defined if three clinical criteria are present or the radiographic criterion is present in the absence of signs and symptoms.

PREVALENCE

Estimates of AS prevalence have been reported between 0.1–0.2% (McVeigh & Cairns 2006), 0.25–1% (Calin 2004) and 0.5% (Wordsworth 2002). This means that whilst patients with AS are commonly seen within rheumatology units AS is relatively uncommon in the community as a whole. The ratio of males to females ranges from 3:1 (Symmons & Bankhead 1994), 2.5:1 (Calin 2004) and 5:1 (McVeigh & Cairns 2006).

MAIN FEATURES OF AS

The key characteristics of AS are listed below. They can be grouped under the headings: clinical, non-musculoskeletal and radiographic features.

Clinical features:

• Pain; low back pain, alternating buttock pain

• Night pain; woken in second half of night with pain and often needing to get up and move about before resuming sleep

• Improvement of pain on exercise

• Spinal stiffness, predominantly in the morning or after rest

• Postural changes – progressive postural change with an increasingly flexed posture, loss of lumbar lordosis, increase thoracic kyphosis and limitation of trunk lateral flexion and rotation

• Muscle spasm

• Enthesitis (see Fig. 19.2for common sites).

Figure 19.2 An example of an enthesitis index.

Non-musculoskeletal features:

• Fatigue

• Iritis

• Lung disease (less than 1%)

• Cardiac disease (less than 1%).

Radiographic features (Fig. 19.3):

• Symmetrical and bilateral changes of sacroiliac joints (sacroiliitis) is usual in cases of established disease

• Vertebral squaring

• Syndesmophyte formation with or without vertebral fusion.

• Calcification of vertebral discs.

Figure 19.3 Anterior-posterior view of the sacroiliac joints in a patient with ankylosing spondylitis. There is bilateral, symmetrical involvement with succinct erosions (arrows).

From Hochberg MC et al (2008) Fig. 108.5, with permission.

The first radiological signs of AS are usually evident as x-ray changes in the sacroiliac joints. However in early disease these changes are not always apparent on pelvic x-ray but can be detected on an MRI scan. In severe cases the progressive formation of syndesmophytes and ossification throughout the axial skeleton can lead to a so called ‘bamboo spine’. In addition to affecting the lumbar spine AS commonly affects the thoracic and cervical spine and less commonly the hip joints.

PSORIATIC ARTHRITIS

Psoriatic arthritis (PsA) is a chronic heterogeneous disease whose pathogenesis is unknown, although genetic, environmental and immunological factors play major roles (Mease & Goffe 2005). It is a progressive condition and without appropriate treatment results in irreversible joint destruction with resultant disability and functional loss. Psoriasis is a skin disorder affecting 2% of the population characterised by plaques of hyperkeratonic skin commonly on extensor surfaces and in the scalp and occasionally more generalised (Veale & Fitzgerald 2002). The skin disease usually pre-dates the arthritis but in as many as 25% of subjects the arthritis might be synchronous or pre-date the skin disease (Wordsworth 2002). If there is a family history of psoriasis a patient can be diagnosed as having psoriatic arthritis without skin disease being present.

The prevalence of PsA is not well known (Boonen at al 2004). Estimates range from 0.04%– 1.2% (Gladman 2006). Sixty percent of patients with PsA will be HLA-B27 positive (Wordsworth 2002). It affects men and women equally, usually between the ages of 20 and 40 years (Hakim & Clunie 2002). PsA may present in one of a number of clinical patterns, the following is based on the description by Gladman (2006):

• Oligoarticular pattern in which four or less large joints are involved in usually an asymmetric distribution.

• Polyarticular pattern (multiple joints) which can appear similar to rheumatoid arthritis (although it is not considered the same condition).

• Predominantly spinal pattern, with sacroiliitis and spondylitis.

• Arthritis mutilans-a form of the disease with severe joint destruction showing characteristic features on x-ray affecting distal interphalangeal joints of hands and feet.

• Distal joint pattern affecting distal interphalangeal joints of hands and feet.

Points 1 and 2 are the commonest presentations. There is some doubt about how strictly PsA exists within these clinical forms (Marsal et al 1999) although four of the five categories can assist in establishing a differential diagnosis (see Ch. 16 to contrast with the features of rheumatoid arthritis).

The clinical and radiographic features are listed below. Patients will not necessarily display all these features especially in early disease.

Clinical features of PsA

• Psoriasis

• Nail lesions (e.g. pitting)

• Asymmetrical distribution of arthritis

• Peripheral joint arthritis with or without axial skeletal involvement

• Distal interphalangeal joint arthritis

• Enthesitis

• Dactylitis.

The radiographic (x-ray) features of established psoriatic arthritis

• Erosions of distal interphalageal joints

• Unilateral or bilateral sacroiliac joint changes

• Spondylitis.

REACTIVE ARTHRITIS AND REITER’S DISEASE

Reactive arthritis (ReA) is a sterile inflammatory arthopathy, which may develop after bacterial or viral infection. A healthy but genetically predisposed individual develops it following an immune system response to an infection. In the gut this is commonly Shigella, Salmonella or Campylobacter infection, and in the genital tract Chlamydia trachomatis (Toivanen 2000). Typically 60–80% of patients with ReA are HLA-B27 positive (Yu & Fan 2001). Reactive arthritis differs from infectious (septic) arthritis in that the infectious organism cannot be cultured from the joint fluid or synovium.

Reiter’s disease (or Reiter’s syndrome) is currently the term applied to a reactive arthritis displaying specific signs. These are the classic triad of arthritis, urethritis (urethral inflammation) and conjunctivitis (Yu & Fan 2001). The common clinical features are listed below.

Common clinical features (Yu & Fan 2001)

• Asymmetrical synovitis of lower limb joints (especially ankle and knee although wrist and other joints can be involved)

• Dactylitis

• Sacroiliitis- 5–10% of patients in early disease and up to 70% if it becomes chronic

• Enthesitis

• Spondylitis.

ReA tends to be a self-limiting condition and 90% of patients recover in the first year (Yu & Fan 2001). It is very important to treat the underlying cause of infection as this settles the arthritis. Treatment is also directed at the joint manifestations of the disease. When reactive arthritis develops as the result of sexually acquired infection it can be called sexually acquired reactive arthritis (SARA). Treatment guidelines are provided for SARA by the British Association for Sexual Health and HIV (2001). It is always important to consider the implications of discussing the history of SARA with the patient when members of their family or friends are present.

ENTEROPATHIC ARTHRITIS

Enteropathic arthritis is an inflammatory arthritis of peripheral joints and axial skeleton associated with chronic inflammatory bowel disease. Peripheral arthritis is relatively common in inflammatory bowel disease and its incidence is 10% in ulcerative colitis and 15–20% in Crohn’s disease (Jewell 1993, Shearman & Finlayson 1989, Wollheim 2001). Axial skeletal involvement has been reported as having an incidence of 10–15% in ulcerative colitis and 15–20% in Crohn’s disease (Wollheim 2001). Peripheral arthritis tends to be asymmetrical and affect the larger joints (hips, knees, ankles and wrists). If there is a spondylitis (inflammation of spinal joints) or sacroiliitis the course of the disease is independent of the bowel condition. In addition to joint features some patients also experience enthesopathies and inflammatory eye conditions.

ASSESSMENT

This section will outline the principles of assessing the spondyloarthropathies and will relate this to intervention by the therapist. Ankylosing spondylitis (AS) is the prototype of the spondyloathropathies (Braun et al 2002) so this section will focus on assessing AS. The principles of assessing peripheral joint arthritis in SpA and peripheral joint arthritis of other diagnostic types are almost identical so the reader should refer to Chapters 3 and 16 for further detail.

The four clinical features of AS, enthesitis, axial involvement, peripheral articular disease, and extra articular features should be assessed (Dougados & van der Heijde 2002). Some areas of potential extra articular problems (skin, eyes, gut) are outside the normal remit of therapists’ roles and require other members of the team to assess and manage them. The assessment and treatment of foot and ankle problems arising from arthritis or enthesitis is sometimes undertaken by a podiatrist rather than a physiotherapist (see Ch. 13). Box 19.2 highlights the elements of a therapist’s assessment.