We present three children with primary subacute epiphyseal and metaepiphyseal osteomyelitis. The diagnosis was delayed because of subtle radiological findings and mild general symptoms. Primary epiphyseal osteomyelitis is extremely rare. We believe that this is the first time that the MRI findings have been presented. In the first case they revealed a perforation into the knee and therefore an intra-articular epiphyseal approach was used for debridement. In the second and third cases the metaepiphyseal lesions showed considerable physical involvement and a metaphyseal approach was chosen. We believe that in this condition MRI is essential both for diagnosis and in the planning of surgical treatment.

We used laser Doppler flowmetry (LDF) with a high energy (20 mW) laser to measure perfusion of the femoral head intraoperatively in 32 hips. The surgical procedure was joint debridement requiring dislocation or subluxation of the hip. The laser probe was placed within the anterosuperior quadrant of the femoral head. Blood flow was monitored in specific positions of the hip before and after dislocation or subluxation.

With the femoral head reduced, external rotation, both in extension and flexion, caused a reduction of blood flow. During subluxation or dislocation, it was impaired when the posterosuperior femoral neck was allowed to rest on the posterior acetabular rim. A pulsatile signal returned when the hip was reduced, or was taken out of extreme positions when dislocated. After the final reduction, the signal amplitudes were first slightly lower (12%) compared with the initial value but tended to be restored to the initial levels within 30 minutes.

Most of the changes in the signal can be explained by compromise of the extraosseous branches of the medial femoral circumflex artery and are reversible. Our study shows that LDF provides proof for the clinical observation that perfusion of the femoral head is maintained after dislocation if specific surgical precautions are followed.