Monoarthritis

Template:DiseaseDisorder infobox Template:Search infobox Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Monoarthritis is inflammation (arthritis) of one joint at a time. It is usually caused by trauma, infection, or crystalline arthritis.

Causes

Septic arthritis

Septic arthritis is due to a bacterial infection to the joint. It requires urgent joint washout in the operating room followed by intravenous antibiotic therapy for large joints. Small joints or children can be treated with repeated aspirations and intravenous antibiotics.

Gout

In gout, the acute inflammatory arthritis is caused by excess uric acid caused by either overproduction or under-excretion. Before the age of menopause, women have a lower incidence than males, but the rates are equal above this age. Gout can cause mono- or polyarthritis, but usually results in monoarthritis first.

Pseudogout

When monoarthritis is caused by pseudogout (calcium pyrophosphate deposition disease, CPPD), the inflammation usually lasts days to weeks, and involves the knees in half of all attacks. Like gout, attacks can occur spontaneously or with physical trauma or metabolic stress. Patients may feel well in between pseudogout attacks, and 5% present with pseudo-rheumatoid symptoms.

Osteoarthritis

Osteoarthritis is a degenerative disease commonly involving the knees and hips. It results from erosion of the cartilage protecting the bones from rubbing together.

Diagnosis

When faced with monoarthritis, one of the main decisions to make is whether to perform a joint aspirate by inserting a needle into the affected joint and removing some fluid for microscopic analysis. This decision is largely taken on inflammatory markers in blood tests (e.g. CRP), fever and the clinical picture. The main use of aspiration is to detect bacteria and neutrophil granulocytes (in septic arthritis) and crystals (crystal arthropathies).

Differential Diagnosis of Monoarthritis

Diseases			Clinical manifestations					Para-clinical findings						Gold standard	Additional findings
			Symptoms				Physical examination
								Lab Findings				Imaging	Histopathology
			Joint Swelling	Fever	Weight loss	Claudication		Biomarker	CBC	ESR	Other
Monoarthritis	Osteoarthritis
	Trauma
	Neoplasms
	Infection	Gonococcal infection
		Nongonococcal bacterial infections
		Mycobacterial infection
		Fungal infection
		Lyme disease
	Crystal-induced arthritis	Gout
		Pseudo-gout
	Systemic disorders	Reactive arthritis
		Psoriatic arthritis
		Inflammatory bowel disease-associated arthritis
		Sarcoid periarthritis
		Rheumatoid arthritis
		Myelodysplastic and leukemic disorders

Related Chapters

• Gout
• Pseudogout
• Septic arthritis
• Osteoarthritis