What finding is typically associated with the suspected diagnosis of a 13-year-old boy presenting with left knee pain and a shortened leg held in external rotation?

In the case of a 13-year-old boy presenting with left knee pain, a shortened leg, and it being held in external rotation, the most appropriate finding associated with this clinical presentation is characterized by radiographs showing an inferior slip of the proximal femoral metaphysis relative to the epiphysis. This finding suggests a condition known as slipped capital femoral epiphysis (SCFE), which commonly occurs in adolescents.

SCFE is a hip condition where the ball at the head of the femur slips off the neck of the femur due to weakness of the growth plate. It often presents with hip or knee pain and is characterized by a typical positioning of the affected leg in external rotation, shortening, and associated symptoms. The specific radiographic finding of slippage, which shows that the metaphysis is angled downward compared to the epiphysis, is crucial for diagnosing SCFE and differentiating it from other potential causes of hip pain in this age group.

The other options present findings that are related to different conditions. Elevated inflammatory markers may suggest an infectious or inflammatory process but are not definitive for SCFE. Avascular necrosis of the femoral head is characterized by different radiographic findings and typically presents with a more insidious onset of symptoms