A 12-year-old male with hip pain presents to the NP clinic. Hip pain has occurred with activity for the past 4-6 weeks, but his pain is worse and now involves the knee. There is no history of trauma. How should the workup be initiated?

• A. Order a hip and knee X-ray
• B. Order a hip X-ray and a sed rate
• C. Perform Trendelenburg's test in the office
• D. Have the child squat in the office to assess the hips

Answer: (C)

When a child has hip pain that also involves the knee, a focused in-office exam of hip function is the best first step. The Trendelenburg test checks hip abductor strength, mainly the gluteus medius, by having the child stand on one leg and watching the pelvis. If the pelvis drops on the opposite side, it signals weakness of the stance leg’s hip abductors and suggests a problem in the hip or its surrounding structures. In a 12-year-old, this finding raises concern for hip pathology that can present with knee pain, such as SCFE or Legg-Calvé-Perthes disease, and it indicates that imaging of the hip is warranted to evaluate for those conditions.

This approach is preferred because it uses a quick, noninvasive bedside assessment to guide next steps. A normal Trendelenburg test doesn’t rule out hip pathology, but a positive sign is a clear reason to obtain hip radiographs (typically AP pelvis with a frog-leg lateral) to look for slipped capital femoral epiphysis or avascular necrosis of the femoral head, whereas starting with imaging in every case would expose the patient to radiation without first confirming the exam findings. The squatting test isn’t as specific for this scenario, and inflammatory markers like a sed rate aren’t the initial step when the key issue is hip stability and weakness revealed by a simple physical exam.