19th January 2024

Differential diagnoses

Osteoarthritis – presents with mechanical pain, usually worse at the end of the day and post-activity. Radiographs may show osteophytes or evidence of degenerative disease in OA.
Diffuse idiopathic skeletal hyperostosis (DISH) – can be asymptomatic or present with back pain and stiffness worse in the morning, in patients between the ages of 50 and 75 years. Radiographs may demonstrate flowing osteophytes along anterior margin of vertebra with normal vertebral bodies and discs.
Psoriatic arthritis – usually presents in patients between the ages of 35 and 45 years, with no preponderance for male sex. Can get unilateral sacroiliitis, and there may be a history of psoriatic skin disease. Dactylitis is more common in psoriatic arthritis. Radiographs may show erosive disease in psoriatic arthritis.
Reactive arthritis – symptoms may be preceded by infection. Skin manifestations and dactylitis are more common in reactive arthritis. Patients usually present with urethritis and conjunctivitis in addition to arthritis. Radiographs may reveal unilateral sacroiliitis in reactive arthritis.
Enteric arthritis – associated with inflammatory bowel disease. Peripheral joints are commonly affected, and patients may also present with extra-articular features such as erythema nodosum or pyoderma gangrenosum. Radiographs may show unilateral sacroiliitis in enteric arthritis.
Discitis – may be accompanied with features of systemic upset, including fever, fatigue, and reduced appetite alongside back pain. MRI or X-rays can show focal spinal abnormalities, and inflammatory markers may be raised in spinal infections.
Vertebral fractures – can be seen in patients with ankylosing spondylitis or occur in patients without the disease. Present with spinal pain and can be identified on radiographs
Primary bone diseases or bony metastases – patients may present with signs and symptoms of the primary malignancy or systemic features such as weight loss and night sweats. Radiographs can reveal vertebral collapse or metastatic deposits in malignancy.
Spinal stenosis – presents with bilateral pain in the buttocks or legs, which is exacerbated by standing, walking or extension of the lumbar region and relieved by bending forwards or sitting. Can also present with neurological symptoms such as numbness and tingling in the lower limbs. Lumbar spine MRI is the investigation of choice of spinal stenosis and may show disc space narrowing.

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