What is a key indicator of hip dysplasia in children?

A key indicator of hip dysplasia in children is leg length discrepancy. Hip dysplasia, or developmental dysplasia of the hip (DDH), occurs when the hip joint doesn't form properly in infants and young children, leading to instability or dislocation of the joint. One of the physical manifestations of this condition can be a noticeable difference in leg lengths. When one leg appears shorter than the other, it can indicate an issue with the alignment or function of the hip joint.

Other symptoms can include limited range of motion in one leg compared to the other, asymmetrical skin folds in the thigh, or a noticeable clicking sound when moving the hip joint. However, a leg length discrepancy can be a clear and observable sign that prompts further investigation into the hip's development.

The other options listed are not directly associated with hip dysplasia. Delayed speech development, increased muscle tone, and frequent upper respiratory infections are not relevant indicators of this specific musculoskeletal condition.