Ultrasonography: an imaging modality enabling the diagnosis of bipartite patella

Ultrasound was used to diagnose bipartite patella in seven adolescents with anterior knee pain, and the findings were compared to those from plain radiography and to those of a group of asymptomatic subjects. In all affected individuals the quadriceps and patellar tendons appeared normal on ultrasound. Sonographic examination of the patella demonstrated an irregularity of the bony contour with occurrence of a cleft between the main part of the patellar body and the large superolateral accessory ossicle. The signal detected in the interface between bones was less echogenic than bone reflecting its fibrocartilaginous nature. The correlation with conventional radiography was absolute, as was the inter- and intraobserver reliability. Ultrasound is thus proposed as a simple and reliable imaging modality in bipartite patella. We do not believe that it should replace the initial radiographic, but it can be used to evaluate the contralateral knee for bilaterality and as an adjunct to therapeutic procedures such as local injections to increase the accuracy of treatment.