Fracture pattern characteristics and associated injuries of high-energy, large fragment, partial articular radial head fractures: a preliminary imaging analysis

All imaging modalities were reviewed by a single fellowship-trained hand and upper extremity, attending physician (JTC). All radiographic data were de-identified prior to analysis, in an attempt to minimize bias. CT scans of the elbow with 1-mm slice thickness were evaluated for the position and size of the fracture fragment in the radial head. Of note, if involved with concurrent elbow dislocation, CT scans were obtained post-reduction and splinting. The axial cut that best revealed the largest diameter of the intact portion of the radial head and associated fracture defect was used to quantify the fracture (Fig. 1). The axial cut that best demonstrated the radial tuberosity was then used as a reference marker to determine the angular location of the fracture (Fig. 2a). The radial tuberosity, designated as the 6 o’clock position, was utilized as a bony marker that was deemed as the most consistent landmark that is least likely to change in the setting of high-energy trauma, which may obscure and change soft tissue position. These selected images were then placed in a Microsoft Powerpoint (Microsoft Corp., Redmond, WA, USA) file. A computer-generated calibrated dial was then created and used as a measurement guide (Fig. 2b). Using the radial tuberosity as a reference point, the calibrated dial was then superimposed on the CT scan cut that best depicted the radial head fracture (Fig. 2c). The radial head fractures were then quantified as an angular amount and as a range on the face of a clock. Fracture fragment anatomy was termed in a specific quadrant based on location on the clock face—fractures between the 12 o’clock and 3 o’clock position were referred to as anterolateral (AL) fragments, between 3 o’clock and 6 o’clock position as posterolateral (PL) fragments, between 6 o’clock and 9 o’clock as posteromedial (PM) fragment, and between 9 o’clock and 12 o’clock as anteromedial (AM) fragments (Fig. 3). Fracture fragments spanning two adjacent quadrants were reported based on the larger fracture fragment component, which was quantified via measurement and percentage comparison. The exact angle was measured using a picture archiving and communication systems (PACS, General Electric Company, Fairfield, CT, USA) angle measuring tool. The percent amount of articular surface involvement in the radial head, and the presence of associated elbow fractures, elbow dislocation/subluxation and other associated injuries were also noted and recorded. The percent amount of articular surface involved was estimated using computed measuring area software (SkyScan High-Resolution MicroCT System, Kontich, Belgium).

Statistical analysis was performed using Student’s t test, and Fisher’s exact test for categorical data. All statistics were analyzed via SPSS 18.0 (IBM Inc., Armonk, NY, USA); a p-value of ≤0.05 was considered significant.