A 12-year-old male with hip pain presenting without trauma should first undergo which assessment?

The correct choice is to perform Trendelenburg's test in the office as an initial assessment for a 12-year-old male with hip pain presenting without trauma. This clinical test is used to evaluate hip stability, strength of the hip abductors, particularly the gluteus medius muscle. It assesses whether the patient can maintain the pelvis level while standing on one leg. A positive Trendelenburg's test indicates weakness or dysfunction on the side opposite to the leg being stood on, which can help identify underlying hip conditions such as developmental dysplasia, osteonecrosis, or hip impingement.

Considering the other options, while imaging studies like x-rays can provide valuable information about the bony structures and potential fractures, they are not the first step in assessing hip pain without trauma. Additionally, laboratory tests such as a sed rate might be more relevant if an inflammatory process is suspected, but they are not necessary at the initial assessment stage. Having the child squat could provide some insight into hip function but does not specifically assess the underlying biomechanics or strength like Trendelenburg's test does. Thus, for an initial functional assessment in this scenario, Trendelenburg's test is the most appropriate choice.