Edited by Laura Lu and Matthew Lindsey - 7/1/2021
Descriptors
Presenting Symptoms:
Joint pain (85%), Effusion (78%), Fever (57%), Erythema, Systemic Toxicity (Diaphoresis 27%, Rigors 19%)
Exam Pearls
Effusion: Hips may be flexed and abducted, knees will likely have effusion on exam (milk the knee, look for medial effusion)
Pain with short arc range of motion (even 5-15 degrees of passive motion elicits significant pain)
Inability to bear weight
Workup
Radiographs: Orthogonal Views of the Joint (e.g. AP and Lateral views). Look for signs of effusion (e.g. radiographic lucent "balloon" surrounding the joint). Identify the presence of implants. Rule out fracture. Recognize joint space available/anatomical variants making aspiration difficult. If implants present, refer to periprosthetic infection page.
Other imaging: None. Advanced imaging in select cases, such as CT scan if NSTI suspected or MRI with contrast if osteomyelitis suspected - staff with senior/fellow/attending before recommending.
Labs:
Serum: ESR, CRP, CBC(WBC). Lyme in children or with high suspicion.
Synovial Aspirate (Gold Standard): Total nucleated cells (diff), gram stain, culture, crystals.
50K total nucleated cells diagnostic, < 25K low risk.
Presence of crystals does not rule out super-infected crystalline arthropathy.
Other: Blood cultures prior to antibiotics, systemic workup if septic.
Management
Need for acute intervention: No intervention in emergency department aside from diagnostic testing.
- Assess urgency (native joint in young patient < 40 years or septic patient more urgent)
- Diagnostic imaging and testing as above
- Keep patient NPO pending above results; staff with relevant senior/fellow/attending
- May warrant ED obs admission to await cell count data
- NO antibiotics prior to synovial fluid aspiration and blood cultures
Aspiration Technique:
Shoulder: Shoulder Aspiration
Elbow: Elbow Aspiration
Wrist: Wrist Aspiration
Hip: Hip Aspiration
Knee: Knee Aspiration
Ankle: Ankle Aspiration
Weight-bearing and range of motion: Weightbearing as tolerated, range of motion as tolerated
Type of immobilization: None
Admission or discharge status:
Admission to relevant service based on coexisting medical issues.
If cell count >50K, NPO, preop clearance/plan for OR, timing pending discussion with senior/fellow/attending
If cell count between 25K and 50K: discuss with senior/fellow/attending
If <25K, low risk of septic arthritis, discuss with senior/fellow/attending
Anticoagulation: If admission, standard prophylactic lovenox or SQH, but must not be given any later than the night before surgery
Antibiotics:
Broad Spectrum: Should cover GPC/GNR (Vanco/Cefepime or Vanc/Zosyn)
Transition to pathogen specific after cultures
Surgical Indications
Absolute: >50K total nucleated cell count without presence of crystals OR culture positive aspiration
Relative: Patient too sick for OR (Bedside needle lavage) Culture positive with common contaminant (Eg: Staph Epidermidis)
Not an indication: Crystalline arthropathy with improvement on appropriate treatment, lyme disease
References
Margaretten ME, Kohlwes J, Moore D, Bent S. Does This Adult Patient Have Septic Arthritis? JAMA. 2007;297(13):1478–1488. doi:10.1001/jama.297.13.1478