Ans. is 'a' i.e., Deveopmental dysplasia of hip Risk factors for DDH/CDHo Femaleso First bomso FamilialDDH is found in familieso Faulty intrauterine position (Breech presentation)o Hormone induced laxityo OligohydramnionClinical features of DDHo Girls are affected six times as often as boys. In one third of cases, bilateral affection occurs. Unless it is specially looked for in infancy - as it always should be - abnormality may not be noticed until the child begins to walk. The clinical findings in older child arei) Limitation of abduction and external rotationii) Limb is in adduction, internal rotation & flexion.iii) Asymmetrical thigh foldiv) Higher buttock fold on the affected side.v) Galeazzi's sign : The level of the knees are compared in a child lying with hip flexed to 70deg and knees flexed. There is a lowering of the knee on the affected sidevi) Ortolani's test may be positive.vii) Trendelenbug's test is positive: This test is performed in an older child. The child is asked to stand on the affected side. The opposite ASIS (that of the normal side) dips down .viii) The limb is short and slightly externally rotated. There is lordosis of the lumbar spine.ix) Telescopy positive : In a case of a dislocated hip, it will be possible to produce an up and down piston- like movement at the hip. This can be appreciated by feeling the movement of the greater trochanter under the fingers.x) A child with unilateral dislocation exhibits a typical gait in which the body lurches to the affected side as the child bears weight on it (Trendelenburg'sgait)An a child with bilateral dislocation, there is alternate lurching on both side (waddling gait).xi) There is compensatory genu valgum as patient tries to keep the foot out (to compensate adduction at hip).