An inflammatory disease of the spine affecting young (usually) HLA-B27 positive adults.
HLA-B27 is present in about 8% of normal population, but up to 90% of patients with ankylosing spondylitis
Possible environmental trigger in these patients: potentially gut micro-flora or mechanical (as yet uncertain)
Males are affected more than women (3:1)
“Rule of twos” – ank spond occurs in:
2% of the general population
2% of HLA-B27 positive people
20% of HLA-B27 positive people with an affected family member
Presentation of ankylosing spondylitis
Episodic inflammation of the sacroiliac joints in late teens/early 20s
Morning low back pain and stiffness
Improves on exercise
May radiate into both buttocks
Extra-spinal features
Other joint pain
Hips (in about 1/3 of patients)
Shoulder girdle, costochondral joints
Peripheral joint involvement in about 25%, usually oligo-articular, large joint & asymmetric
Inflammation of the Achilles tendon insertion (enthesitis)
Uveitis
Aortitis & aortic insufficiency
Apical fibrosis
Mnemonic for ankylosing spondylitis
The six “A”s of Ank spond:
Atlanto-axial subluxation
Anterior uveitis
Apical fibrosis
Aortic regurgitation
Amyloidosis (renal)
Achilles involvement (enthesitis)
Examination of ankylosing spondylitis
Mobility
Reduced flexion in the lumbar spine
Modified Shober’s test: distance between the midpoint of the posterior superior iliac spines and a point 10cm vertically above when standing erect, following maximal forward flexion of the spine (normal > 15cm)
Increased extension at cervical spine
Increased occiput to wall distance: patient stands facing away from wall with heels touching wall. Occiput may not be able to touch wall in ankylosing spondylitis
Reduced rotation at lumber, thoracic and cervical spine
Other
Reduced chest expansion often present (restrictive pattern on lung function tests)
