A 12-year-old with right knee pain, obesity and no prior URI is presenting with limited ROM of the right hip. What is the best next step?

In this scenario, the correct choice is obtaining an AP and lateral x-ray of the hip. When evaluating a child with joint pain and limited range of motion, especially in the context of possible underlying structural issues, imaging is a critical component of the diagnostic process.

X-rays are typically the first-line imaging study for assessing musculoskeletal conditions in the pediatric population. They can help identify any obvious bony abnormalities, such as fractures, dislocations, or developmental issues like Perthes disease or slipped capital femoral epiphysis, which are particularly relevant in a child with knee pain and limited hip movement.

In cases where obesity is a factor, the likelihood of certain conditions increases, and having a clear picture of the hip joint is crucial for diagnosis and further management. After the x-ray results are available, they may guide whether further imaging, such as MRI, is necessary to assess soft tissue structures or more subtle pathologies.

While seeking a physical therapy evaluation or referring to an orthopedic specialist may be appropriate later on based on the findings, the immediate best next step is to obtain x-rays, as they will provide vital information to guide the subsequent management plan.