An eight-year-old girl presented with a septic subluxation of the right hip secondary to spontaneous drainage of a psoas pyomyositis. The course of the infection was protracted, and the symptoms were mild relative to the magnitude of the psoas abscess and the volume of purulence in the hip that caused subluxation of the femoral head. At the time of surgical drainage, the hip capsule directly communicated with the psoas abscess along the course of the iliopsoas tendon sheath. Methicillin-sensitive Staphylococcus aureus (MSSA) was the microorganism that was isolated from the abscess and from the hip joint.
Drainage of the psoas abscess and septic arthritis coupled with antibiotic treatment eliminated the infection, and the child returned to normal activities. At the five-year follow-up, she was asymptomatic, but the subtle changes in the sphericity of the femoral head as well as the slight joint-space narrowing may be associated with problems in the future.