Assessment of the Standard Rotational Profile of the Radius and Ulna with Computed Tomography Imaging for the Treatment of Forearm Malunions.

OBJECTIVE

Accurate preoperative assessment of radius and ulna rotation during fixation of complex forearm fractures or during the treatment of malunion/nonunion of the radius or ulna is essential for an optimal operative outcome. A CT scan is commonly used for preoperative assessment of complex fractures and certainly of malunions and nonunions of the forearm. To our knowledge, there is no standardized CT scan-based measurement of the rotation of the radius and ulna. The purpose of this study was to determine the standard rotational profile of the radius and ulna utilizing computed tomography scans in individuals without osseous deformity.

METHODS

Computed tomography scans of 23 patients without osseous deformity or pathology of the radius or ulna were assessed. The rotation of the ulna was measured by determining the orientation of the ulnar styloid with respect to the coronoid. The rotation of the radius was measured by determining the orientation of the radial styloid relative to the bicipital tuberosity.

RESULTS

The ulnar styloid was a mean of 172.0 ± 19.3 degrees of supination relative to the coronoid process. The radial styloid was a mean of 167.8 ± 18.3 degrees of supination relative to the bicipital tuberosity. There was no significant difference in radial or ulnar rotation regarding age, sex, race, or laterality.

CONCLUSION

Given the standard deviations present in both groups, there is a range in normal anatomy with regard to the rotational profile of the radius and ulna.

CLINICAL RELEVANCE: Combined with clinical assessment of range of motion, measurements of radial and ulnar rotation on cross-sectional CT imaging remain a useful adjunct for surgical planning and clinical decision making. This information is critical for surgeons planning nonunion or malunion repairs with rotational deformity.