Radial and ulnar medullary canal diameter in children: Anatomical limitations of elastic stable intramedullary nailing

INTRODUCTION: Surgery is inevitable for children who cannot achieve the ideal reduction in forearm fractures. The biggest limitation of the elastic stable intramedullary nail (ESIN) fixation method is the diameter of the medullary canal. This study aimed to measure the medullary canal diameters of the radius and ulna at different ages in children. METHODS: The forearm radiographs of 540 children were retrospectively reviewed. All background characteristics, including weight, sex, maturity of the radius and ulna, and length of the radius and ulna, were measured and recorded. Children with radius and ulnar diameters shorter than 2 mm were analyzed by statistical regression analysis by SPSS software. RESULTS: When we set 2 mm as the minimum medullary canal diameter, our results showed that patients aged 3–12 years had radius and ulnar diameters under this limit. The regression analysis of risk factors with the 2 mm diameter limitation had significant differences based on age (P = 0.006) and sex (P = 0.033). There was no significant difference between patients based on weight (P = 0.056), ulnar length (P = 0.946), radius length (P = 0.503), radius maturity (P = 0.655), or ulnar maturity (P = 0.774). CONCLUSIONS: The average medullary canal diameter remained constant until 12 years of age. However, the average diameter length did not increase significantly after the age of 12 years. The incidence of medullary canal diameter shorter than 2 mm was correlated with age and sex. Our results suggest that surgeons should pay attention to the medullary diameter of the anteroposterior and lateral radiographs to determine the ESIN diameter.