Basics
Description
- Localized to 1 joint, not migratory
- 1 etiology does not exclude another
- Infectious (septic) arthritis: Rapidly destructive process causes significant disability
- Contiguous extension (cellulitis, osteomyelitis), hematogenous spread, direct inoculation
- Predisposing factors:
- Local pathology (inflammatory arthritis, trauma, prosthetic joint)
- Immunosuppression
- IV drug use
- Crystalline:
- Gout: Uric acid overproduction or underexcretion, deposited within and around joints.
- Pseudogout: Calcium pyrophosphate
- Noninflammatory conditions
- Osteoarthritis (DJD), trauma (fractures, hemarthrosis), autoimmune disorders
- Progressive joint destruction; mechanical dysfunction
- Bone reactive changes (spurring)
- Subchondral bony erosions
Etiology
- Infectious (septic)
- Most common organisms nongonococcal
- Gram-positives: Streptococcus, Staphylococcus (80%)
- Some associations:
- Staphylococcus aureus: (trauma, IV drug use)
- Neisseria gonorrhea (STD)
- Salmonella (sickle cell) but most common causes in sickle cell same (Staphylococcus, Streptococcus)
- Less common: Fungal (chronic), spirochete (Lyme), viral (polyarticular), mycobacteria (TB)
- Crystalline:
- Gout: Uric acid overproduction, underexcretion within, around joints
- Tophi: Crystal deposits near recurrent flare sites. Progressive enlargement, may ulcerate "spit out" (discharge) crystals
- Negatively birefringent crystals
- Pseudogout: Calcium pyrophosphate
- Positively birefringent crystal
- Bariatric surgery: Postoperative gout flares common, frequent, significant. Prophylactic treatment effective, recommended
- Inflammatory
- Diligent search for underlying cause, resultant conditions: arthridites (rheumatoid, psoriatic), inflammatory bowel disease, Reiter syndrome
- Noninflammatory conditions
- Osteoarthritis or degenerative joint disease (DJD), overuse, overload (obesity)
- Trauma (fractures, hemarthrosis)
- Hemorrhagic disorders
- Neuropathic disorders (Charcot joint)
- Infectious (septic) arthritis
- Low incidence, high morbidity, sepsis (8%)
- Most common: S. aureus, hip > knee, 50% coexisting osteomyelitis
- Present like adults: Joint swollen, painful, worsened with weight bearing, movement; constitutionally ill (fever, lassitude)
- Immediate aspiration, empiric treatment, admission mandatory
- Inflammatory
- A diagnosis only after septic joint excluded; then considerations same as adults
- Noninflammatory:
- Orthopedic considerations to not overlook:
- Salter-Harris epiphyseal plate fractures
- Congenital hip dysplasia
- Slipped capital femoral epiphysis (SCFE)
- Legg-Calve-Perthes:
- Osteonecrosis femoral head
- Age 4-9
- Bleeding disorders, hemorrhage
Diagnosis
Early accurate diagnosis allows directed therapy, earlier resumption of function, activities of daily living (ADL); longer-term morbidity lessened
Signs and Symptoms
- Isolated to 1 joint, not migratory
- Acute pain, swelling, redness, warmth
- Decreased range of motion, nonweight bearing (effusion, pain, osteomyelitis)
- Infectious (septic) arthritis:
- Constitutionally ill, fever, chills
- Larger joints swollen, painful range motion
- Knee > hip = shoulder > ankle > wrist
- N. gonorrhea: Urethral discharge painful, purulent (males)
- Lyme disease:
- Spirochete Borrelia burgdorferi
- Deer tick (Ixodes dammini)
- Circular expanding, centrally clearing, eruption (erythema chronicum migrans)
- Knees, shoulders most common
- Crystalline:
- Sudden, severe pain, swelling, erythema
- Recurrent, self-limited flares
- Gout: Great toe joint ("podagra") > ankle > tarsal joints > knee
- Tophi: Crystal granulomas overlying affected joints; ulcerate, drain crystals
- Pseudogout: Knee > wrist > ankle = elbow
- Inflammatory:
- Protean manifestations, findings related to systemic conditions
- Individual, multiple, combination organ system involvement. Example: Reiter syndrome: Iritis, urethritis, arthritis
- Noninflammatory conditions
- Osteoarthritis (DJD):
- Stiffness AM (inactivity), after activity (synovial gelling), relieved with rest
- Trauma: Acute or distant, gradual swelling episodes, pain pattern same as DJD
- Neuropathic: Charcot joint ("bag of bones"), little or no pain-chronic neuropathy
- Hemarthrosis, hemorrhagic disorders
History
- See "Description," "Etiology," "Pediatric Considerations," and "Signs and Symptoms."
- Complete, meticulous history: Joint issues or involvement (recent, remote), systemic conditions (direct, local, remote manifestations), immune status (HIV, medications, disease process), STD (history, exposure, treatment type and duration), IV drug use.
Physical Exam
See "Description" and "Signs and Symptoms."
Essential Workup
- Meticulous history and physical exam
- Condition-related diagnostic studies
- Arthrocentesis for synovial fluid analysis is the definitive diagnostic procedure.
Diagnosis Tests & Interpretation
Lab
- Blood testing never the key diagnostic studies of choice for monoarticular arthritis; provides ancillary, corroborative, exclusionary information.
- Arthrocentesis for synovial fluid aspiration and analysis the definitive diagnostic procedure and studies.
- Synovial fluid culture the definitive synovial study regarding infection, but results not immediate (inherent nature of the test)
- Fluid appearance: Clear versus turbid, serous versus bloody, viscosity ("string sign"), volume removed, associated pain (levels, trends)
- Synovial fluid white blood cells (WBC), polymorphonuclear (PMN) predominance suggests septic etiology
- WBC >50,000/mm3 increases likelihood of septic arthritis
- Synovial glucose: Most useful compared to concurrent blood glucose levels
- Synovial glucose less than half blood value indicates likely septic process
- Gram stain (positive stain): Directs initial antibiotic selection, administration
- Gram + cocci: Vancomycin
- Gram - cocci: Ceftriaxone
- Gram - rods: Ceftazidime
- Gram stain (negative stain): Clinical suspicion for septic joint: Empiric vancomycin + ceftazidime or aminoglycoside
- Viscosity: "String sign"
- Slowly drip fluid off needle or syringe, noting the length of the "stringing."
- Noninflammatory fluid has longer strings
- Inflammatory fluid will drip like water
- Crystal analysis: Polarized light microscopy for birefringent crystals: Gout (negative), pseudogout (positive)
- Rheumatologic "screening panel" for suspected disease: Uric acid, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), anticyclic citrullinated peptide (ACCP)
- Lyme testing (anti-Borrelia titers or "Lyme titers") for monoarticular arthritis presenting in endemic areas
- Fat globules in bloody aspirate: Suspect fracture with marrow (fat globules), synovial space communication
Imaging
- Plain films reasonable cost-effective choice:
- Joint surfaces: Chondral, subchondral erosions, joint margin destruction or reactive bone formation (osteophytes, "spurring"), loose bodies, fractures
- Infectious: As above plus soft-tissue swelling, joint capsule distortion
- Crystalline: As above plus soft-tissue calcification, tophi usually located on or near frequent, repetitive joint flares
- Ultrasound: Detects joint fluid, tissue and vascular perfusion, periarticular structures, foreign bodies (especially if small, superficial organic composition of tissue density)
- Guides aspiration attempts
- MRI detects bone necrosis, subtle fractures
- Bone or gallium scans do not distinguish Infectious versus inflammatory, especially chronic
Diagnostic Procedures/Surgery
See "Diagnostic Tests & Interpretation" above.
- Arthrocentesis for synovial fluid aspiration, analysis the definitive diagnostic procedure and laboratory studies.
Differential Diagnosis
See "Etiology" and "Signs and Symptoms" "Pediatric Considerations" above.
Treatment
Pre-Hospital
Alluding to subsequent headings containing all pertinent consideration.
Initial Stabilization/Therapy
- Joint immobilization, position of comfort
- Vascular access for rapid, titratable, predictable medication effects
- Symptom control: Pain, nausea, vomiting, fluid replenishment
- Joint aspiration as soon as practicable; analysis directs therapy, disposition
Ed Treatment/Procedures
- See "Diagnostic Procedures" above
- Septic arthritis:
- Urgent empiric IV bactericidal antibiotics: Ceftriaxone, vancomycin for Staphylococcus, Streptococcus, gonococcal arthritis
- Subsequent outpatient antibiotics (PICC line, oral) therapy duration variable, multifactorial: Joint involved, organism, underlying health, patient compliance, medical costs
- Surgical irrigation considerations ("washouts"): Joint involved, open versus closed, single versus multiple sequential, comorbid conditions, patient compliance, medical costs
- Crystalline:
- Treatment goals: (1) Quell the acute flare: NSAIDs (indomethacin, naproxen), colchicine, steroids; (2) only after acute exacerbation quelled:
- Prophylaxis with flare prevention medications (colchicine, naproxen), begin urate-lowering therapy (allopurinol, febuxostat)
- Febuxostat as effective or greater than allopurinol for gout flares, tophus area, uric acid levels.
- Probenecid: Efficacious long-term uricosuric, alone or in conjunction with allopurinol
- Noninflammatory:
- NSAIDs, analgesics
- Physical therapy, rehabilitation
- Orthopedic trauma: Immobilize, pain control, ensure neurovascular status intact
- Hemorrhagic causes: Correction of factor levels, component replacement
Follow-Up
Disposition
Admission Criteria
- Unable to perform ADL
- Evidence systemic illness, metabolic derangement (sepsis, DKA)
- Any joint requiring surgical intervention (including serial washouts)
- Intractable pain
- All septic arthritis
- General medical/surgical bed
- Intensive care unit if generalized sepsis, metabolic derangement
- Crystalline:
- Intractable nausea, vomiting, diarrhea
- Septic joint superimposed on other arthritis
Discharge Criteria
- Symptoms (including pain) controlled, comorbid conditions stable, managed appropriately
- Medication compliance: Can obtain medications (economically, logistically), understands dosages, time intervals.
- Timely follow-up possible
Issues for Referral
Immediate consultation, admission for infectious etiologies, intractable pain, poorly controlled comorbid illnesses, interference with ADL
Follow-Up Recommendations
- As soon as practicable, with health care providers best suited, capable of treating the condition in question.
- If unable to acquire the appropriate care in a timely manner, return to ED (safety net).
Pearls and Pitfalls
- Joint aspiration with Gram stain of fluid is the most important aspect of securing a diagnosis, directing initial management
- Suspect septic arthritis in the presence of Intra-articular corticosteroid administration, diabetes, drug abuse, trauma, injections through cellulitis and extra-articular infection
Additional Reading
- Carpenter CR, Schuur JD, Everett WW, et al. Evidence-based diagnostics: Adult septic arthritis. Acad Emerg Med. 2011;18(8):781-796.
- Genes N, Chisolm-Straker M. Monoarticular arthritis update: Current evidence for diagnosis and treatment in the emergency department. Emerg Med Pract. 2012;14(5):1-19.
- Smith BG, Cruz AI Jr, Milewski MD, et al. Lyme disease and the orthopaedic implications of Lyme arthritis. J Am Acad Orthop Surg. 2011;19(2):91-100.
Codes
ICD9
- 274.00 Gouty arthropathy, unspecified
- 711.90 Unspecified infective arthritis, site unspecified
- 716.90 Arthropathy, unspecified, site unspecified
ICD10
- M00.9 Pyogenic arthritis, unspecified
- M10.00 Idiopathic gout, unspecified site
- M19.90 Unspecified osteoarthritis, unspecified site
SNOMED
- 3723001 Arthritis (disorder)
- 396234004 Infective arthritis (disorder)
- 48440001 Articular gout (disorder)