Septic arthritis is estimated to affect 4-37 in 100,000 children with the knee being the most affected joint (1), and Staphylococcus aureus the most common causative bacteria.
There are minimal case reports published on septic arthritis progressing to a necrotising infection, let alone in a paediatric case.
We present an unusual case of an 8 month old girl, who was diagnosed with necrotising fasciitis secondary to untreated septic arthritis of her ankle, requiring debridement and free flap reconstruction.
She initially presented with an acutely swollen right lower limb and was admitted due to the concern for non-accidental injury to her foot and ankle. On subsequent reviews she was noted to have cellulitis of her foot and ankle, and was commenced on intravenous antibiotics.
An MRI performed on the day of presentation reported findings suspicious for septic arthritis, myositis and fasciitis. She proceeded to theatre for a surgical debridement of the septic ankle joint and surrounding necrotising fasciitis. Staphylococcus aureus was found to be the causative agent and following six surgical debridements the patient underwent a free latisimmus dorsi flap and skin graft for soft tissue coverage of the open ankle joint and surrounding soft tissue defect. There were technical challenges encountered during the reconstruction procedure including vasospasm of the pedicle and the presence of significant fibrosis.
This case not only highlights the possibility of septic arthritis progressing to necrotising infections, but also the difficulties in performing a free flap reconstruction in an infant.