Meredith L. Anderson MD, Presenter: Nothing to Disclose

A. Noelle Larson MD, Abstract Co-Author: Nothing to Disclose

John Skinner MD, Abstract Co-Author: Nothing to Disclose

Richard Berger MD, Abstract Co-Author: Nothing to Disclose

Kimberly Katz Amrami MD, Abstract Co-Author: Nothing to Disclose

The purpose of the current study was to assess the utility of the radial torsion angle as described by Bindra et al. in the clinical setting among patients with previous forearm fracture compared to normal controls.

In this cross-sectional study, the radial torsion angle was compared in 5 normal subjects and 24 patients with a unilateral forearm fracture. Bilateral upper extremity computerized tomography (CT) scans were used to calculate the radial torsion angle in both forearms using the methods of Bindra et al. Side-to-side difference was defined as the absolute difference in the radial torsion angle between the right and left forearms. Radial torsion angle and side-to-side differences were compared between patients and controls with an unpaired t-test. Inter-rater reliability was determined between two blinded musculoskeletal radiologists. Radial torsion angle and side-to-side differences were correlated with forearm range of motion using linear regression.

The twenty-four cases included twelve (50.0%) distal radius fractures, 8 (33.3%) forearm diaphyseal fractures, and 4 (16.7%) Galeazzi fractures with a mean patient age of 38.4 ± 12.4 years. Mean radial torsion angle was 31.9 ± 23.0 º in the affected side and 37.4 ± 18.8 º in the unaffected side. Mean pronation in the affected extremity was 52.4 ± 31.7 º and 83.9 ± 6.1º in the unaffected extremity. Mean side-to-side radial torsion angle was 14.2 ± 9º in the cases verses 3.3 ± 1.3º in normal subjects (p-value <0.0001).

The mean side-to-side difference between patients with previous forearm fracture compared to normal subjects is 10.9 ± 2.1º (p-value <0.0001). The radial torsion angle is decreased in the affected extremity by 5.5º (95% CI 1.6, 3.4) compared to unaffected extremity (p-value 0.124). Among patients with previous forearm fracture, a 20º loss of pronation is associated with a loss of 11.1º in the radial torsion angle (p-value 0.047).

The radial torsion angle and side-to-side differences can be used as a predictor of forearm malrotation and is a useful tool in surgical management of forearm malunions.

Anderson, M, Larson, A, Skinner, J, Berger, R, Amrami, K, Quantification of Radial Torsion Angle with Computerized Tomography: A Clinical Comparison.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014144.html