Assessing distal radius malrotation following fracture using computed tomography

Area of Science:

• Orthopedic Surgery
• Radiology
• Biomechanics

Background:

• Distal radius fractures commonly involve displacement, including shortening, angulation, and rotation of the distal fragment.
• Malrotation of the distal radius fragment can negatively impact distal radio-ulnar joint function.
• Rotational deformities are often difficult to assess accurately using conventional radiography.

Purpose of the Study:

• To determine the frequency and extent of malrotation in distal radius fractures.
• To establish a reliable method for measuring distal radius fragment rotation using computed tomography (CT).

Main Methods:

• Retrospective analysis of 85 CT scans (35 distal radius fractures, 50 normal controls).
• Development and application of a simple method to measure distal radius rotation relative to the diaphysis on routine CT scans.
• Statistical analysis (Mann-Whitney) and reliability testing (ICCs, Bland-Altman plots) were performed.

Main Results:

• The median radial rotation in the fracture group was 3° pronation (range -24° to 31°), compared to 1° pronation (range -15° to 4°) in controls.
• The absolute rotation angle was significantly greater in the fracture group (median 10° vs. 3°, p < 0.001).
• Approximately 75% of fractures exhibited rotation outside the normal range observed in controls, with 26 cases showing appreciable rotation.

Conclusions:

• Malrotation is a common, yet often overlooked, complication of distal radius fractures.
• A simplified CT-based method for measuring radial rotation is reliable and practical for clinical use.
• Accurate assessment of radial rotation is crucial for effective treatment planning and management of distal radius malunion.