Monoarticular Arthritis

Aka: Monoarticular Arthritis, Monoarthritis, Monoarticular Joint Pain, Acute Monoarthritis

1. See Also
   1. Joint Pain
   2. Joint Pain in Children
   3. Polyarticular Arthritis
   4. Fever in Rheumatic Disease
   5. Viral Causes of Arthritis
   6. Cutaneous Signs of Rheumatic Disease
   7. Enteropathic Arthritis
   8. Ocular Manifestations of Rheumatologic Disease
   9. Rheumatologic Conditions affecting the Foot
   10. Rheumatologic Conditions affecting the Hand
   11. Rheumatologic Conditions affecting the Hip
   12. Rheumatologic Conditions affecting the Knee
   13. Rheumatologic Conditions affecting the Low Back
   14. Rheumatologic Conditions affecting the Wrist
   15. XRay Changes in Rheumatic Conditions
   16. Septic Joint
2. Definition: Acute Monoarthritis
   1. Acute single joint inflammation developing in <2 weeks
3. Pitfalls
   1. Septic Joint
      1. Septic Arthritis is a rheumatologic emergency (infection may destroy a joint in 48 hours)
      2. Arthrocentesis is the only absolutely reliable method to exclude Septic Joint
         1. No blood test (including elevated Uric Acid level or normal WBC Count, CRP) excludes Septic Arthritis
      3. Do not start antibiotics prior to Arthrocentesis, and do initiate antibiotics afterward if findings suggest
4. Causes: Common Monoarticular (Mnemonic: SINGL JOINT)
   1. Septic Arthritis (most important to rule-out)
      1. Bacterial Arthritis
      2. Fungal Arthritis
      3. Parasitic Arthritis
      4. Gonococcal Arthritis (esp. young sexually active adults)
      5. Mycobacteria
   2. Internal derangement or Trauma
      1. Meniscus Injury
      2. Ligament tears
      3. Overuse syndromes
   3. Inflammatory Arthritis - Aseptic (Reactive Arthritis)
   4. Neuropathy (Charcot's Joint)
   5. Gout, Pseudogout and other crystal-induced Arthritis
   6. Lyme Disease
   7. Juvenile or adult Rheumatoid Arthritis
   8. Osteoarthritis
   9. Osteomyelitis
   10. Ischemic bone (avascular necrosis)
   11. Neoplasms
       1. Osteoid Osteoma
       2. Pigmented Villonodular synovitis
       3. Bony metastases
   12. Trauma
       1. Overuse injury
       2. Fractures
       3. Hemarthrosis
5. Causes: Other Causes
   1. Common in Primary Care
      1. Osteoarthritis
      2. Gouty Arthritis
      3. Trauma (e.g. foreign body, Fracture, hemarthrosis)
   2. Autoimmune Conditions or Vasculitis
      1. Systemic Lupus Erythematosus
      2. Rheumatoid Arthritis
      3. Sarcoidosis
   3. Spondyloarthropathy
      1. Ankylosing Spondylitis
      2. Spondyloarthopathy due to Inflammatory Bowel Disease related
      3. Psoriatic Arthritis
      4. Reactive Arthritis
   4. Miscellaneous causes
      1. Acute Retroviral Syndrome (initial HIV Presentation)
      2. Behcet Syndrome
      3. Hemoglobinopathy
      4. Familial Mediterranean Fever
      5. Osteitis Deformans (Paget's Disease)
      6. Still Disease
      7. Bacterial Endocarditis
      8. Amyloidosis
6. History
   1. See Joint Pain
   2. Predisposing factors
      1. Pre-existing Osteoarthritis or Rheumatoid Arthritis
         1. Septic Arthritis
      2. Prolonged Corticosteroid use
         1. Septic Arthritis
         2. Avascular necrosis
      3. Tick Bite
         1. Lyme Disease
      4. IV Drug Abuse, Immunodepression
         1. Septic Arthritis
   3. Timing of pain and swelling
      1. Extremely rapid onset within minutes
         1. Traumatic Arthritis (e.g. Fracture)
      2. Onset over hours to days
         1. Septic Arthritis
         2. Crystal Arthritis (e.g. gout)
      3. Onset over weeks to months
         1. Systemic Rheumatic disease
         2. Indolent infection
         3. Osteoarthritis
         4. Tumor
      4. Chronic or Long-standing
         1. Aggravated Osteoarthritis
         2. Crystal Arthritis
   4. Mediating factors
      1. Worsens with activity and improves with rest
         1. Mechanical cause (Trauma, Osteoarthritis)
      2. Morning Stiffness and worse with rest
         1. Inflammatory Arthritis (e.g. Rheumatoid Arthritis)
   5. Location
      1. Migratory
         1. Gonococcal Arthritis (Gonorrhea) initially migratory, but later affects primary joint)
         2. Rheumatic Fever
      2. Consider multiple joint involvement
         1. Oligoarthritis (<=4 joints)
         2. Polyarthritis
7. History: Extraarticular Symptoms
   1. See Joint Pain
   2. See Differential Diagnosis below
8. Symptoms
   1. Joint Pain and swelling
9. Signs
   1. Joint effusion
      1. Most specific sign of intraarticular process and joint inflammation
   2. Distinguish articular from periarticular Arthritis
      1. Bursitis
      2. Fracture
      3. Tendonitis
   3. Range of motion
      1. Active range of motion limitation
         1. Periarticular problems
      2. Both Passive AND Active range of motion limitation
         1. Articular problems
   4. Normal joint exam
      1. Referred pain
   5. Palpation
      1. Swelling and pain
   6. Stress Pain (pain at extreme range of motion)
      1. Most sensitive sign of joint inflammation
   7. Examine all joints
      1. Assess for Polyarthritis
   8. Skin exam
      1. Psoriatic Plaque, Nail Pitting or dactylitis
      2. Overlying Cellulitis or Septic Bursitis
      3. Skin Desquamation over joint (Gouty Arthritis)
      4. Erythema Nodosum (Sarcoidosis, Inflammatory Bowel Disease)
      5. Erythema over joint
         1. Infection (Cellulitis, Septic Bursitis, Septic Joint)
         2. Crystal Arthritis (e.g. Gouty Arthritis)
10. Labs
    1. See Joint Pain
    2. Arthrocentesis
       1. Single most important test to consider (critical if possible Septic Joint)
11. Imaging
    1. See Joint Pain
    2. Plain film XRay
       1. Indicated for Trauma or focal bone pain
       2. Acute findings include Fracture or avulsion
       3. Subacute findings include Osteomyelitis or malignancy
       4. Chronic findings seen in Osteoarthritis, Rheumatoid Arthritis, or Gouty Arthritis
12. Differential Diagnosis
    1. Septic Arthritis
       1. See Pitfalls above (most important to exclude)
       2. Risks include prosthetic joints, joint surgery, RA, CKD, DM, IVDA, Skin Infection, age over 80 years old
       3. Includes Gonococcal Arthritis (esp. sexually active young patients)
    2. Osteoarthritis
       1. Asymmetric Joint Pain and stiffness in the hands, spine, knees and hips
       2. Brief morning stiffness (<30 min), and Joint Pain after activity
       3. Heberden's Node (DIP), Bouchard's Node (PIP) are pathognomonic (1st MCP is commonly affected)
    3. Gouty Arthritis
       1. Thiazide Diuretics, Purines and Trauma may trigger gouty attacks
       2. Rapidly developing red, swollen joints (esp. 1st MTP)
       3. With chronic gout, tophi destroy joints
       4. Renal stones may form
    4. Behcet Syndrome
       1. Oral Ulcers
    5. Reiter's Syndrome
       1. Urethritis
       2. Conjunctivitis
       3. Diarrhea
       4. Rash
    6. Psoriatic Arthritis
       1. Psoriasis
       2. Nail Pitting
       3. Dactylitis (sausage-like swelling of digits)
    7. Ankylosing Spondylitis
       1. Uveitis
       2. Low Back Pain
    8. Sarcoidosis
       1. Hilar Adenopathy
       2. Erythema Nodosum
    9. Gonococcal Arthritis
       1. Young adults with high risk sex history
       2. Urethral discharge or Dysuria (Pharyngitis may also be present)
       3. Migratory polyarthralgias at onset, then settles in a single joint
       4. Tenosynovitis of hands and feet
       5. Pustules
    10. Hemarthrosis (Coagulopathy)
        1. Bleeding tendency
        2. Anticoagulant use
    11. Avascular Necrosis
        1. Systemic Lupus Erythematosus
        2. Corticosteroid use
        3. Alcohol Abuse
13. References
    1. Becker (2016) Am Fam Physician 94(10):810-6 [PubMed]