Arthritis is inflammation of one or more joints. There are two major categories of arthritis.
The first type is caused by wear and tear on the articular cartilage (Osteoarthritis) through the natural aging process, through constant use, or through trauma (post-traumatic arthritis). The second type is caused by one of a number of inflammatory processes.
Most common diagnoses in acute monoarticular arthritis: crystalline, septic, osteoarthritis, trauma.
Most important diagnostic test in acute monoarticular arthritis: synovial fluid analysis and culture.
Most important diagnoses to rule out in chronic monoarticular arthritis: indolent infection, tumor.
Best diagnostic tests in chronic monoarticular arthritis: synovial fluid analysis, radiography, magnetic resonance imaging, arthroscopy with synovial biopsy and culture.
Diseases that Commonly Present with Monoarthritis
Septic diseases, Bacterial, Mycobacterial, Lyme disease, Fungal, Crystal deposition diseases, Gout, Calcium pyrophosphate dihydrate deposition disease (pseudogout), Hydroxyapatite deposition disease, Calcium oxalate deposition disease, Traumatic, Fracture, Internal derangement, Hemarthrosis, Other diseases, Osteoarthritis, Juvenile idiopathic arthritis, Coagulopathy, Avascular necrosis of bone, Foreign-body synovitis, Pigmented villonodular synovitis, Palindromic rheumatism
Inflammatory and Noninflammatory Causes of Chronic Monoarthritis
Internal derangement of the knee
Avascular necrosis of bone
Monoarticular presentation of rheumatoid arthritis
Pigmented villonodular synovitis
The history and physical examination, not laboratory testing, are the best tools for diagnosis.
The two most common causes of polyarthritis are osteoarthritis and rheumatoid arthritis.
The extraarticular features (such as the malar rash of systemic lupus erythematosus, SLE) are often key to diagnosing polyarticular syndromes.
Laboratory tests are most useful in confirming a diagnosis based on the history and physical examination.
Diseases with Acute Polyarthritis Symptoms
OTHER INFLAMMATORY CONDITIONS
Polyarticular and systemic JIA
Acute sarcoid arthritis
Acute rheumatic fever
Systemic lupus erythematosus
Viral (especially rubella, hepatitis B and C, parvovirus, Epstein–Barr, HIV)
Distribution of Joint Involvement in Polyarthritis
JOINTS COMMONLY INVOLVED
JOINTS COMMONLY SPARED
Knee, wrist, ankle, hand IP
Knee, shoulder, wrist, elbow
Wrist, MCP, PIP, elbow, glenohumeral, cervical spine, hip, knee, ankle, tarsal, MTP
DIP, thoracolumbar spine
First CMC, DIP, PIP, cervical spine, thoracolumbar spine, hip, knee, first MTP, toe IP
MCP, wrist, elbow, gleno-shoulder, ankle, tarsal
Knee, ankle, tarsal, MTP, first toe IP, elbow, axial
Knee, ankle, MTP, first toe IP, wrist, MCP, hand IP, axial
Knee, ankle, elbow, shoulder, MCP, PIP, wrist, axial
First MTP, instep, heel, ankle, knee
Knee, wrist, shoulder, ankle, MCP, hand IP, hip, elbow
MCP, wrist, ankle, knee, hip, feet, shoulder
CMC, Carpometacarpal; DIP, distal interphalangeal; IP, Interphalangeal; MCP, metacarpophalangeal; MTP, metatarsophalangeal. PIP, proximal interphalangeal;
Synovial Fluid Analysis
wbc/mm3 = Granulocytes/mm3, PMN = polymorphonuclear leukocytes