For this study, 150 trainee ballet dancers (80 males, 70 females) belonging to the ballet schools of the "Teatro Alla Scala" in Milan, aged between 10 and 21 years, were considered. From September 2005 to September 2007, the researchers retrospectively created a database in which they collected clinical examinations and imaging studies of the dancers. 19 dancers (9 males, 10 females) presented stress fractures in the base of the metatarsal bones. The average age of the patients was 16.4 years. In all of them the appearance of pain and/or discomfort was gradual,  related to specific foot positions and increased training sessions. In a range of 7 to 20 days, a standard radiograph was taken which in 11 patients was negative (grade 1-2), in 8 cases showed a cortical reaction (grade 3) and only in one case a stress fracture was observed (grade 4). Later, a MRI was performed, in which the stress fracture and intramedullary edema were evident. All patients were treated non-surgicall...