"Head at risk" sign is seen in -: (A) Perthes disease, (B) Ewing's sarcoma, (C) Osteomylitis, (D) Paget's disease
Answer is A. Ans. is 'a' i.e., Perthes disease o "Head at risk" sign is a radiological prognostic sign for Perthes disease (also k/a Legg-Calves- Perthes disease or Coxa Plana or Idiopathic avascular necrosis of femoral head).o Disease mainly affects children o Classification of' Head at risk" sign :i) Lateral subluxation (most important prognostic factor): due to articular cartilage overgrowthii) Calcification lateral to epiphysis: calcification in the overgrown cartilageiii) Osteolysis in the superolateral part of the femoral metaphysis: Gage's signiv) Horizontal physisv) Metaphyseal cysts.