Ankylosing spondylitis

introduction

Ankylosing spondylitis is an generalized chronic inflammatory disease.

it primarily affects the spine and sacroiliac joints, causing persistent back pain and stiffness. The condition may also extend to involve the hips and shoulders, and in some cases, the peripheral joints

There is a strong familial tendency in ankylosing spondylitis, with a well-established association with the genetic marker HLA-B27.

The condition predominantly affects males, with onset most commonly occurring between the ages of 15 and 25 years

causes

Ankylosing spondylitis (AS) is a genetically influenced immunopathological disorder

There are various theories about the ‘triggering factor’ that initiates the abnormal immune response

It may be a bacterial antigen, which closely resembles HLA-B27 that induces an antibody response, which also targets the HLA-B27 positive cells; or, as in the case of RA, the HLA-B27 molecule may be involved in the presentation of a specific antigen to the T cells, which then react with the antigen-presenting cells.

pathology

Synovitis of the sacroiliac and vertebral facet joints leads to the destruction of articular cartilage and peri-articular bone.

The costovertebral joints are also commonly affected, resulting in reduced chest expansion and impaired respiratory movement.

Additionally, inflammation at the fibro-osseous junctions involves the intervertebral discs, sacroiliac ligaments, symphysis pubis, manubrium sterni, and the bony insertions of major tendons.

pathological changes occur at 3 stages :

• an inflammatory reaction with cell infiltration, granulation tissue formation and erosion of adjacent bone
• the replacement of the granulation tissue by fibrous tissue
• ossification of the fibrous tissue, leading to ankylosis of the joint

Ossification across the surface of the disc gives rise to small bony bridges or syndesmophytes linking adjacent vertebral bodies.

clinical features

1. A teenager or young adult typically presents with recurrent episodes of backache and stiffness that persist over several years.
2. Over time, the pain and stiffness become continuous, accompanied by additional symptoms such as general fatigue, joint pain and swelling, tenderness at the Achilles tendon insertion, “foot strain,” and intercostal pain with tenderness.
3. Symptoms are usually worse in the early morning and after periods of inactivity.
4. The characteristic posture includes loss of normal lumbar lordosis, increased thoracic kyphosis, and a forward thrust of the neck.
5. To maintain balance and an upright stance, patients often stand with their hips and knees slightly flexed. In advanced cases, these postural changes may become fixed deformities.
6. Spinal mobility is reduced in all directions, with loss of extension being the earliest and most significant limitation.

special test

1. wall test :

the patient is asked to stand with his back to the wall; heels, buttocks, scapulae and occiput should all be able to touch the wall simultaneously.

If extension is seriously diminished the patient will find this impossible

In the most advanced stage the spine may be completely ankylosed from occiput to sacrum – sometimes in positions of grotesque deformity.

2. Schober’s Test:

Examiner marks a point at L5 (usually at the dimples of Venus).

patient is asked to bend forward in normal individual the distance increases by at least 5cm

3. finger to floor test

the patient is asked to bend forward and touch the floor

then the examiner measure the distance between fingertips and floor

Greater distance = more stiffness.

diagnosis

The ESR and CRP are usually elevated during active phases of the disease. HLA-B27 is present in 95 percent of cases.

in X ray there can be erosion and fuzziness of the sacroiliac joints.

Reference

Bope, E.T., & Kellerman, R.D. (2022). Conn’s Current Therapy. Elsevier Health Sciences.

Joshi, J., & Kotwal, P. (2007). Essentials of Orthopaedics and Applied Physiotherapy (2nd ed.). Jaypee Brothers Medical Publishers.

van der Heijde, D., et al. (2017). 2016 update of the ASAS–EULAR management recommendations for axial spondyloarthritis. Annals of the Rheumatic Diseases, 76(6), 978–991. https://doi.org/10.1136/annrheumdis-2016-210770

Khan, M.A. (2002). Ankylosing Spondylitis: Clinical features, diagnosis, and management. The American Journal of Medicine, 113(7), 524–534.

Resnick, D., & Niwayama, G. (1981). Diagnosis of Bone and Joint Disorders. W.B. Saunders.

Rudwaleit, M., et al. (2005). The development of assessment tools for Ankylosing Spondylitis. Rheumatology, 44(8), 939–947.

Magee, D.J. (2014). Orthopedic Physical Assessment (6th ed.). Elsevier.

Hoppenfeld, S. (1976). Physical Examination of the Spine and Extremities. Appleton & Lange.

Solomon, L., Warwick, D., Nayagam, S. (2010). Apley’s System of Orthopaedics and Fractures (9th ed.). Hodder Arnold.

Bojan, A., & Braun, J. (2009). Peripheral arthritis and enthesitis in ankylosing spondylitis. Clinical and Experimental Rheumatology, 27(4 Suppl 55), S86–S91.