Pediatric emergency medicine trisk 2378 2378

e-TABLE 94.13
CLINICAL AND LABORATORY FEATURES DIFFERENTIATING
PYOGENIC SEPTIC ARTHRITIS FROM LYME ARTHRITIS
Variable

Pyogenic

Lyme disease

Clinical

Swollen, exquisitely
tender
Refusal to bear weight
Range of motion
severely limited
Fever is common
Joint erythema is
common

Swollen, less tender than with
pyogenic arthritis
Usually can walk without difficulty
Range of motion diminished, but can
still flex and extend to some degree
Fever is uncommon
Joint erythema is less common

Laboratory a

ESR/CRP elevated

ESR/CRP normal or elevated
Synovial fluid WBC Synovial fluid—variable, and over ½
>100,000 cells/mm3
have synovial fluid WBC >100,000
cells/mm3
Does not improve
Can have spontaneous resolution after
without treatment
several weeks

Outcome
a Data

from Dart AH, Michaelson KA, Aronson PL, et al. Hip synovial fluid cell counts in children from a
Lyme disease endemic area. Pediatrics 2018;141(5):e20173810.
ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; WBC, white blood cell count.