Monoarthritis

CLINICAL DIAGNOSTIC MANUAL

Monoarthritis is a condition characterised by inflammation of a single joint. It can be acute or chronic and may be associated with a variety of causes, including infections, autoimmune diseases, crystal deposits, and trauma. Accurate identification of the underlying cause is crucial for appropriate management and the prevention of potentially serious complications.

Condition	Symptoms and Clinical Signs	Suspected Diagnosis	Confirmatory Diagnosis
Septic Arthritis	Severe pain, swelling, erythema, fever, chills	History of systemic infection, acute symptoms of monoarthritis	Synovial fluid analysis and culture, positive blood cultures
Gout	Intense and sudden pain, swelling, erythema, especially in the first metatarsophalangeal joint	History of recurrent episodes of pain in the same joint	Presence of monosodium urate crystals in synovial fluid, elevated serum uric acid levels
Pseudogout	Pain, swelling, erythema, typically in knees, wrists, or ankles	History of recurrent episodes similar to gout	Presence of calcium pyrophosphate dihydrate crystals in synovial fluid
Reiter’s Disease (Reactive Arthritis)	Joint pain, inflammation, history of recent urinary or intestinal infection	History of prior infection, symptoms of arthritis, urethritis, and conjunctivitis	Synovial fluid analysis, infection testing (cultures, PCR), positive HLA-B27
Psoriasis	Joint pain and inflammation, presence of psoriatic skin lesions	History of psoriasis, articular symptoms	Clinical analysis of skin lesions and joint symptoms
Traumatic Hemarthrosis	Sudden pain and swelling following trauma	History of recent trauma	Presence of blood in synovial fluid, imaging studies (X-ray, MRI)
Joint Deposits due to Leukemia	Joint pain and swelling, systemic symptoms of leukemia (fatigue, fever, weight loss)	History of systemic symptoms, abnormal haematological findings	Blood tests, bone marrow biopsy
Secondary Reactive Arthritis	Joint pain and inflammation, history of recent genital or intestinal infection	History of prior infection, articular symptoms	Synovial fluid analysis, infection testing (cultures, serology)