A 7-year-old presents with a limp and pain in his hip. What condition is likely indicated if the x-ray is normal?

When considering a 7-year-old with a limp and hip pain, a normal x-ray suggests that certain conditions may be more likely than others. Toxic synovitis, also known as transient synovitis, is a common condition in this age group characterized by hip pain and a limp, often occurring after a viral infection.

This condition typically does not cause significant changes visible on x-rays, especially in the early stages, as it primarily involves inflammation of the synovial membrane without structural bone changes. Children with toxic synovitis usually present with a sudden onset of hip pain, decreased range of motion, and sometimes fever. Despite the normal x-ray results, clinical evaluation can often reveal tenderness in the hip, and further investigation such as an ultrasound may show fluid collection around the joint.

In contrast, other conditions such as Legg-Calve-Perthes disease, septic arthritis, and slipped capital femoral epiphysis typically present with findings that can be detected on x-ray, especially if the condition has progressed. For instance, Legg-Calve-Perthes disease can eventually show avascular necrosis of the femoral head, septic arthritis usually presents with joint effusion or destruction, and slipped capital femoral epiphysis often