Purpose. A retrospective study was carried out in order to determine t
he role of sonography in establishing the diagnosis in extremity osteo
myelitis. Materials and methods. The imaging documents of 24 infants a
nd children aged from 2 weeks to 13 years with osteomyelitis (acute 21
, chronic 3) were reviewed. Sonograms and conventional radiographs wer
e available in all patients. Additional skeletal scintigraphy had been
performed in 13 patients and MRI in only 3. Special emphasis was put
on the different ultrasound findings and their onset in the course of
disease. Results. Intra-articular fluid collections (in 15 cases) and/
or subperiosteal abscess formation (in 12) were the most frequent earl
y sonographic findings, and preceded any radiographic changes by sever
al days in 11 of these cases. Together with positive clinical signs of
inflammation, they were usually sufficient to establish the correct d
iagnosis. In selected cases, fluid or abscess puncture for immediate m
icroscopic and later bacteriological studies was carried out under son
ographic control. In addition, sonography was also able to detect supe
rficial cortical erosion and even an intramedullary focus in a very yo
ung patient. Conclusion. Ultrasonography is a very helpful tool for es
tablishing the correct diagnosis in osteomyelitis and reducing the fre
quency of additional imaging studies.