Breech presentation is a risk factor for dysplasia of the femoral trochlea

We read Øye et al.’s article (Øye et al. 2016) with great interest. On reviewing our patient cohort presenting with dis- locating patellae mainly in adolescents and early adulthood, of those with trochlear dysplasia (TD) as defi ned by Henri Dejour on lateral plain radiograph (Dejour et al. 1990), we had 4 breeches in 133 patients. The breech presentation rate in the United Kingdom is essentially the same. The key to Øye et al.’s paper is the defi nition of TD; a femoral sulcus angle of >157° on ultrasound (Oye et al. 2015). We have no experience of ultrasound use in neonates, but we have under- taken a study on children and adolescents (Toms et al. 2009) which concluded “In patients with patellar instability, CT and MR are reliable techniques for measuring the femoral sulcus angle but US, particularly of the articular cartilage, is not. MR is therefore the most suitable tool for longitudinal studies of the femoral sulcus.” We were interested in using ultrasound to monitor changes in the femoral sulcus during the fi nal growth spurt in at risk patients.