II. Definitions
- Acute Monoarthritis
- Acute single joint inflammation developing in <2 weeks
III. Pitfalls
-
Septic Joint
-
Septic Arthritis is a rheumatologic emergency
- Infection may destroy a joint in 48 hours
- Mortality is as high as 7 to 20%, especially in advanced age
-
Septic Arthritis presentations may be subtle (no fever, no erythema)
- Consider Septic Arthritis in any patient with painful, significantly limited joint range of motion
-
Arthrocentesis is the only absolutely reliable method to exclude Septic Joint
- No blood test (including elevated Uric Acid level or normal WBC Count, CRP) excludes Septic Arthritis
- Chronically deranged joint is higher risk for Septic Arthritis (differentiate Septic Joint from acute exacerbation)
- Do NOT start Antibiotics prior to Arthrocentesis, and DO initiate Antibiotics afterward if findings suggest
- See exceptions under management below (e.g. Septic Shock)
-
Septic Arthritis is a rheumatologic emergency
IV. Causes: Common Monoarticular (Mnemonic: SINGL JOINT)
-
Septic Arthritis (most important to rule-out)
- Bacterial Arthritis
- Fungal Arthritis
- Parasitic Arthritis
- Gonococcal Arthritis (esp. young sexually active adults)
- Mycobacteria
- Internal derangement
- Meniscus Injury
- Ligament tears
- Overuse syndromes
- Inflammatory Arthritis - Aseptic (e.g. Spondyloarthropathy, Reactive Arthritis)
- Neuropathy (Charcot's Joint)
- Gout, Pseudogout and other crystal-induced Arthritis
- Lyme Disease
- Juvenile or adult Rheumatoid Arthritis
- Osteoarthritis
- Osteomyelitis
- Ischemic bone (avascular necrosis)
- Neoplasms
- Osteoid Osteoma
- Pigmented Villonodular synovitis
- Bony metastases
-
Trauma
- Overuse injury
- Fractures
- Hemarthrosis
V. Causes: General
- Common and important Monoarthritis in Primary Care
- Osteoarthritis
- Gouty Arthritis
- Pseudogout
- Trauma (e.g. foreign body, Fracture, hemarthrosis, osteonecrosis)
- Septic Arthritis
- Lyme Disease
- Autoimmune Conditions or Vasculitis (typically Polyarthritis)
-
Spondyloarthropathy (typically Polyarthritis)
- Ankylosing Spondylitis
- Spondyloarthopathy due to Inflammatory Bowel Disease related
- Psoriatic Arthritis
- Reactive Arthritis
- Miscellaneous causes
- Acute Retroviral Syndrome (initial HIV Presentation)
- Behcet Syndrome
- Hemoglobinopathy
- Familial Mediterranean Fever
- Osteitis Deformans (Paget's Disease)
- Still Disease
- Bacterial Endocarditis
- Amyloidosis
- Malignancy
- Coagulopathy
- Hypothyroidism
- Hypoparathyroidism
VI. History
- See Joint Pain
- Predisposing factors
- Pre-existing Osteoarthritis or Rheumatoid Arthritis
- Prolonged Corticosteroid use
- Septic Arthritis
- Avascular necrosis
- Tick Bite
- IV Drug Abuse, Immunodepression
- Timing of pain and swelling
- Extremely rapid onset within minutes
- Onset over hours to days
- Septic Arthritis
- Crystal Arthritis (e.g. gout)
- Onset over weeks to months
- Systemic Rheumatic disease
- Indolent infection
- Osteoarthritis
- Tumor
- Chronic or Long-standing
- Aggravated Osteoarthritis
- Crystal Arthritis
- Mediating factors
- Worsens with activity and improves with rest
- Mechanical cause (Trauma, Osteoarthritis)
- Morning Stiffness and worse with rest
- Inflammatory Arthritis (e.g. Rheumatoid Arthritis)
- Worsens with activity and improves with rest
- Location
- Migratory
- Gonococcal Arthritis (Gonorrhea) initially migratory, but later affects primary joint)
- Rheumatic Fever
- Consider multiple joint involvement
- Oligoarthritis (<=4 joints)
- Polyarthritis
- Migratory
VII. History: Extraarticular Symptoms
- See Joint Pain
- See Differential Diagnosis below
VIII. Symptoms
- See Joint Pain
- Joint Pain and swelling
IX. Signs
- Joint effusion
- Most specific sign of intraarticular process and joint inflammation
- Distinguish articular from periarticular conditions
- Range of motion
- Consider Septic Arthritis in any patient with painful, significantly limited joint range of motion
- Active range of motion limitation
- Periarticular problems
- Both Passive AND Active range of motion limitation
- Articular problems
- Normal joint exam
- Referred pain
- Palpation
- Swelling and pain
- Stress Pain (pain at extreme range of motion)
- Most sensitive sign of joint inflammation
- Examine all joints
- Assess for Polyarthritis
- Skin exam
- Psoriatic Plaque, Nail Pitting or Dactylitis
- Overlying Cellulitis or Septic Bursitis
- Skin Desquamation over joint (Gouty Arthritis)
- Erythema Nodosum (Sarcoidosis, Inflammatory Bowel Disease)
- Erythema over joint
- Infection (Cellulitis, Septic Bursitis, Septic Joint)
- Crystal Arthritis (e.g. Gouty Arthritis)
X. Labs
- See Joint Pain
-
Arthrocentesis
- Single most important test to consider (critical if possible Septic Joint)
- See Synovial Fluid White Blood Cell Count
XI. Imaging
- See Joint Pain
- Plain film XRay
- Indicated for Trauma or focal bone pain
- Acute findings include Fracture or avulsion
- Subacute findings include Osteomyelitis or malignancy
- Chronic findings seen in Osteoarthritis, Rheumatoid Arthritis, or Gouty Arthritis
XII. Differential Diagnosis
-
Septic Arthritis
- See Pitfalls above (most important to exclude)
- Risks include prosthetic joints, joint surgery, RA, CKD, DM, IVDA, Skin Infection, age over 80 years old
- Includes Gonococcal Arthritis (esp. sexually active young patients)
-
Osteoarthritis
- Asymmetric Joint Pain and stiffness in the hands, spine, knees and hips
- Brief morning stiffness (<30 min), and Joint Pain after activity
- Heberden's Node (DIP), Bouchard's Node (PIP) are pathognomonic (1st MCP is commonly affected)
-
Gouty Arthritis
- Thiazide Diuretics, Purines and Trauma may trigger gouty attacks
- Rapidly developing red, swollen joints (esp. 1st MTP)
- With chronic gout, tophi destroy joints
- Renal stones may form
- Behcet Syndrome
- Reiter's Syndrome
-
Psoriatic Arthritis
- Psoriasis
- Nail Pitting
- Dactylitis (sausage-like swelling of digits)
- Ankylosing Spondylitis
- Sarcoidosis
-
Gonococcal Arthritis
- Young adults with high risk sex history
- Urethral discharge or Dysuria (Pharyngitis may also be present)
- Migratory polyarthralgias at onset, then settles in a single joint
- Tenosynovitis of hands and feet
- Pustules
- Hemarthrosis (Coagulopathy)
- Bleeding tendency
- Anticoagulant use
- Avascular Necrosis
XIII. References
- Mann and Papp (2022) Crit Dec Emerg Med 36(17): 22-8
- Becker (2016) Am Fam Physician 94(10):810-6 [PubMed]