<prompt> The most common cause of limp in a child of seven years old is ?T.B. hipCongenital displacement of hipPehes diseaseSlipped upper femoral epiphysis  <response>: PEHES DISEASE : Its a disease charecterised by avascular necrosis of head of femur of a child The avascular epiphysis is almost always completely revascularised and replaced but resulting in variable degree of deformity of the femoral head and growth disturbance. pathogenesis : 4 stage on the basis of evolution of disease Stage of Avascular Necrosis Stage of Revascularization Fragmentation Stage of Ossification Healing Remodeling Residual stage symptoms : 5-10yr old child Characteristic presentation is a painless limp. May present with limp alone with pain. The child appears to be well not sick . The hip looks to be deceptively normal -- there may be little wasting. Abduction Internal rotation are nearly always limited. Antalgic gait in the irritable phase or Trendelenburg gait. ref : maheswari 9th ed 