A rare presentation of necrotising fasciitis and myositis with femoral head necrosis and gas in the femur

Necrotising fasciitis is a rapidly progressive, polymicrobial synergistic soft tissue infection that spreads along fascial planes beneath seemingly normal skin. The relatively benign appearance of the extremity is misleading and often results in delay in diagnosis and increased morbidity or death. Involvement of bone is not a recognised feature. Successful management requires early detection, radical surgical debridement and broad spectrum intravenous antibiotics. We report an unusual case of necrotising fasciitis in a 61-year-old male who presented with musculoskeletal symptoms and gas within the femoral head as well as surrounding soft tissues. This resulted in necrosis of the femoral head with the development of chronic osteomyelitis, requiring long-term antibiotics and ultimately proximal femoral excision. We describe a previously unreported presentation of this condition with musculoskeletal involvement and discuss the potential pitfalls in delayed diagnosis.