Limping is a common reason for parents to bring their children to emergency departments. Fischer et al state that 77% of acute, atraumatic limp is dealt with in the ED, and 20% do not even complain of pain. Our job as physicians is to complete appropriate assessments to not miss any serious pathology. Specifically, differentiating between transient synovitis (TS) and septic arthritis (SA) of the hip can be difficult and frustrating for everyone.
TS is an inflammation of the joint space, classically following a URI, with a benign clinical course.
SA is an infectious arthritis associated with poor outcomes with diagnostic delays, including osteonecrosis, growth arrest, and sepsis. Both can both present as an atraumatic, acutely irritable hip with progressive signs of fever, limp, refusal to bear weight, limited range of motion, and abnormal labs. This overlap makes them difficult to differentiate. Although the diagnostic gold standard is to perform an invasive arthrocentesis (positive synovial culture), can we diagnose using clinical criteria alone, such as Kocher's criteria?
What are Kocher's clinical criteria for septic arthritis?
- Fever > 38.5C
- Non-weight bearing on affected side
- ESR > 40 mm/hr
- WBC >12k
Can we use clinical criteria alone to distinguish transient synovitis from septic arthritis?