[Knee pain in a child : watch out for the hip !]

This is a case report of a 13-year old patient presenting with knee pain after a bike accident. Multiple investigations and medical examinations focused on the knee. They did not show any abnormality. About one year later, the patient comes back with increased hip pain, limited internal rotation and shortening of the left limb. Hip X-Ray exams reveal a bilateral slipped capital femoral epiphysis requiring already an osteotomy. Slipped capital femoral epiphysis is a disorder of the proximal femoral epiphysis. The femoral neck is displaced anteriorly and rotates externally while the epiphysis remains in the acetabulum. This pathology is more common in preadolescent boys and can be associated with hormonal disorders. Patients present with an externally rotated gait, a limited internal rotation, associated hip and knee pain. Diagnosis might be missed when patients present with knee pain and can lead to delayed treatment. When facing knee pain, it is essential to perform a clinical examination of the hip. Radiography is the first medical imaging. Surgical treatment by in situ fixation is recommended and prevents further slip with a high rate of success. When delayed, a much more invasive approach is required. A delay in diagnosis adversely affects long-term outcomes.