O1066: Radiographic Measurements to Determine the Development of the Radial Bow

Background: Radial bowing is necessary to maintain rotation of the forearm. Fractures of the forearm that affect the radial bow and/or deformity of the radius may disrupt the ability of the forearm to rotate normally. The purpose of this study was to generate a predictive equation of the radial bow as a function of age to aid in diagnosis and treatment of forearm fractures and congenital differences.

Methods: A retrospective review of forearm radiographs from children ages 1-17 with no previous history of upper extremity injury or condition was performed. Patient demographics and measurements of the amount of bowing at the proximal, middle and distal third of the radius and the location of the most extreme bowed position were recorded. A linear regression analysis was performed.

Results: Fifty-six forearm radiographs were measured. The average age of the patients was 8.35 years (Range: 0-16 years). The average amount of radial bowing at the proximal, middle and distal thirds of the radius for patients ages 0 to 5 was 3.66mm, 5.60mm, and 5.39mm, for patients ages 6-11 was 5.64mm, 9.48mm, and 9.04mm, and ages 11 to 17 was 7.96mm, 12.06mm, and 11.11mm. The average amount of maximum radial bowing for patients ages 0 to 5, 6 to 10, and 11 to 17 was 6.18mm, 10.21mm and 13.14mm, respectively. As the chronological age at the me of the radiograph increased, there was an increase in maximum radial bow with an R2 value of 0.92. This correlates with the equation y = 9.39x + 63.50.

Conclusion: The average amount of radial bow and the amount of the maximum radial bow increases with chronological age. The predictive equation developed can aid in the detection of more subtle fractures of the radius including plastic deformation/greenstick fractures as well as congenital differences. The equation developed may also be used to assess fracture reduction and ensure restoration of the normal radial bow has occurred.