<prompt> Perthes disease is -Fracture of femoral shaftOsteochondritis of femoral epiphysisInfarction of femoral headFracture dislocation of femoral neck  <response>: Ans. is b i.e.. Osteochondritis of femoral epiphysis Perthes diseaseo Perthes disease is also known as osteochondritis deformans juvenilis or Coxa plana or Pseudocoxalgia. Perthes disease is an osteochondritis of the epiphysis of the femoral head capital femoral epiphysis. In the disease, the femoral head becomes partly or wholly avascular and deformed. The disease occurs commonly in males in the age group of 5-10years.Etiology of Perthes diseaseo Perthes disease is the most common form of osteochondroses osteochondroses are characterized by avascular necrosis AVN and defective endochondral ossification of primary or secondary ossification centers,o The etiology remains unknown, but is currently accepted that the disorder is caused by an interruption of the blood supply to the capital femoral epiphysis, causing avascular necrosis.Clinical features of Perthes diseaseo Perthes disease is common in male of age group 5-10 years.o Pain in the hip, often radiating to knee,o Limp antalgic limpo Limitation of movementAbduction, internal rotation and extension are limited, therefore there is adduction, external rotation, and flexion deformity,o Shortening of limb.o Positive trendelenburg test.o During the disease process, bone age is 1-3 years lower than the normal. After healing, bone age returns tonormal.Radiological investigations for Perthes diseaseo Following radiological investigations are used :-X-ray hipFindings are :-Increased medial joint spaceWidening of femoral neckLateral extrusion lateral subluxationMetaphyseal cysts and rarefaction of metaphysisHorizontal physis with speckled calcification lateral to itFragmentation of femoral head with increased density irregular densities in the epiphysisBone scanMay show a decrease uptake by femoral head.MRIIt is the investigation of choice as it can diagnose Perthes disease in early stages when X-ray is normal.MRI tells about :-Extent of area involvedSphericity of the headSubluxation of the headThus MRI helps better in planning for management.Treatment of Perthes diseaseo Preventing the head from mis-shapening while the bone is in softening phase, is the primary aim of the treatment,o The head is required to be kept inside the acetabulum while the revascularisation takes place head containment.o This may be achieved by conservative methods plaster, splint etc or by operation containment osteotomy. 