The Development of the Radial Bow in Children: Normative Values.

Background: Radial bowing is necessary for forearm rotation. Fractures or deformities of the forearm that affect the radial bow may disrupt normal forearm rotation.

Objective: The purpose of this study was to evaluate the development and establish normative values for the pediatric and adolescent radial bow.

Methods: A retrospective review of radiographs from children aged 0-17 years with no previous history of an upper extremity fracture or condition was performed. Patient demographics, maximal radial bow location, and depth were recorded in millimeters and as percentages of the total radial length. The proximal, middle, and distal third radial bows were measured. Means and standard deviations were utilized to establish average measurements by age group. Pearson correlation coefficients assessed the relationship between radial bowing and age.

Results: A total of 505 forearm radiographs were measured. The average age of the patients was 10.0 years (SD: 5.2). The maximal radial bow location remained consistent with age, with a mean value of 61.7%. The maximal radial bow depth marginally decreased with age, with a mean value of 7.7%. The proximal, middle, and distal third maximal radial bows (measured in millimeters) increased with age.

Conclusions: The maximal radial bow depth marginally decreases with increasing age, while the location of the maximal radial bow remains consistent as age increases. These measurements may be used to assess fracture reduction to ensure proper restoration of the radial bow during fracture and congenital condition treatment. Furthermore, they can aid in the detection of subtle fractures of the radius, including plastic deformations and greenstick fractures.