Musculoskeletal Sonography Facilitates the Diagnosis of Adolescent Acute Tibial Tubercle Cortical Avulsion Fracture

Acute tibial tubercle cortical avulsion fracture is not common. We describe a 13-year-old boy with a mild limp and swelling pain in the left lower knee after a fall. Physical examination revealed local tenderness and swelling over the left tibial tubercle. Initial left knee radiographs revealed a small linear indistinct radiopaque shadow anterior to the tibial tubercle. Musculoskeletal sonography disclosed a small displaced fragment over the anterior portion of the left tibial tubercle and a smaller partially detached fragment over the anterior portion of the left anterior proximal tibial metaphysis. Cortical avulsion fracture was suspected; the diagnosis was confirmed after taking a right knee radiograph for comparison. The patient gradually recovered after conservative treatment.Musculoskeletal ultrasound is a useful screening tool and can be used to facilitate diagnosis.