- Clinical science
Ankylosing spondylitis (spondyloarthritis) is a chronic inflammatory disease of the axial skeleton that leads to partial or even complete fusion and rigidity of the spine. Males are disproportionately affected and upwards of 90% of patients are positive for the HLA-B27 genotype, which predisposes to the disease. The most characteristic early finding is pain and stiffness in the neck and lower back, caused by inflammation of the vertebral column and the sacroiliac joints. The pain typically improves with activity and is especially prominent at night. Other articular findings include tenderness to percussion and displacement of the sacroiliac joints (Mennell's sign), as well as limited spine mobility, which can progress to restrictive pulmonary disease. The most common extra-articular manifestation is acute, unilateral anterior uveitis. Diagnosis is primarily based on symptoms and x-ray of the sacroiliac joints, with HLA-B27 testing and MRI reserved for inconclusive cases. There is no curative treatment, but regular physiotherapy can slow progression of the disease. Additionally, NSAIDs and/or tumor necrosis factor-α inhibitors may improve symptoms. In severe cases, surgery may be considered to improve quality of life.
- Sex: ♂ > ♀ (3:1)
- Age: 15–40 years
- Lifetime prevalence in the US: ∼0.5%
Epidemiological data refers to the US, unless otherwise specified.
- Genetic predisposition: 90–95% of patients are HLA-B27 positive.
- Most common presenting symptoms: back and neck pain
- Limited mobility of the spine (especially reduced forward lumbar flexion)
- Inflammatory enthesitis (e.g., of the Achilles tendon, iliac crests, tibial tuberosities): painful on palpation
- Arthritis outside the spine: hip, shoulder, and knee joint
- Most common: acute, unilateral (∼ 25% of cases)
- Gastrointestinal symptoms: associated with chronic inflammatory bowel disease (∼ 5–10% of cases, see also: or )
- Fatigue, weakness, fever, weight loss
- Restrictive pulmonary disease due to decreased mobility of the spine and thorax
- Physical examination, patient history, and pelvic x-ray: If results are conclusive, no additional testing is required!
- If inconclusive → HLA-B27 testing
- If still inconclusive → pelvic MRI
Chest expansion measurement: in full expiration and inspiration
- Pathological difference: < 2 cm
- Physiological difference: > 5 cm
- Spine mobility tests
- Examination of the hip
- ↑ CRP and ESR
- Auto-antibodies (e.g., rheumatoid factor, antinuclear antibodies) are negative
- HLA-B27 positive in 90–95% of cases
- Can help confirm a diagnosis or evaluate the severity of disease, but is not required for the diagnosis
- Changes are generally more evident in later disease
- Sacroiliac joints: signs of sacroiliitis, including ankylosis of sacroiliac joints
- Loss of lordosis with increasing abnormal straightening of the spine
- Sclerosis of the vertebral ligamentous apparatus
- Syndesmophytes resulting in a so-called 'bamboo spine' in anteroposterior radiograph in the later stages (see the table in “Differential diagnosis” below)
- Signs of spondyloarthritis, including ankylosis of intervertebral joints
Mild courses may only exhibit inflammatory changes in the sacroiliac joints on x-ray after a number of years.
- More sensitive than CT scan for detecting sacroiliitis 
- Best method for early detection
- Disc prolapse
- Vertebral osteomyelitis
- Other spondyloarthritides (e.g., reactive arthritis, psoriasis arthritis, arthritis associated with inflammatory bowel disease)
Diffuse idiopathic skeletal hyperostosis (DISH; also called Forestier's disease or hyperostotic spondylosis)
- Definition: degenerative disease of the vertebral column (especially the thoracic and lumbar spine), which is characterized by calcification and ossification of spinal ligaments and entheses
- Limited mobility
- Mild or even no pain at all
- Treatment: symptomatic
- Osteophytes of the spine
The differential diagnoses listed here are not exhaustive.
- Consistent and rigorous physical therapy
- Independent exercises
- Medical therapy
Surgery: in severe cases to improve quality of life
- Severe deformity of the spinal column
- Instability of the spine
- Neurologic deficits
- Joint replacement
- Spinal fusion
Physical therapy is the most important treatment modality!