Obturator internus muscle abscess in children: report of seven cases and review.

Obturator internus muscle (OIM) abscess is an uncommon entity often mistaken for septic arthritis of the hip. We describe seven children with OIM abscess and review seven previously reported cases. The most common presenting symptoms were hip or thigh pain (14 patients), fever (13), and limp (13). The hip was flexed, abducted, and externally rotated in 11 patients. Magnetic resonance imaging and computed tomography (CT) were diagnostic for OIM abscess in the 14 patients. Associated abscesses were located in the obturator externus muscle (5 patients), psoas muscle (2), and iliac muscle (1). The etiologic agents were Staphylococcus aureus (8 patients), Streptococcus pyogenes (2), Neisseria gonorrhoeae (2), and Enterococcus faecalis (1). Three patients underwent CT-guided percutaneous drainage, and three had surgical drainage. Three patients had ischial osteomyelitis in addition to OIM abscess. The 11 children with uncomplicated OIM abscess were treated for a median of 28 days. All patients had an uneventful recovery.