Fig. 9.

Cupid’s bow vs. biconcave fracture. (a) Diagram and lateral radiograph depict Cupid’s bow or balloon disk at multiple levels in a 17 year-old boy treated with glucocorticoids for vasculitis. This normal variant is a curved indentation centred at the posterior third of the endplate (arrows). The shape resembles Cupid’s bow (diagram, bottom), and when present at adjacent endplates, it gives the impression of disk expansion, hence it is also known as ‘balloon disk’. (b) Biconcave endplate fracture at L5, in a 10 year-old boy treated with glucocorticoids for acute lymphoblastic leukemia. There is interruption of the superior endplate of L5, the endplate concavities are centered at the mid-disk rather than the posterior third, there is overall height loss, and adjacent levels are not affected