A new method to locate the radial head "safe zone" on computed tomography axial views

作者：Zhan, Y.; Luo, C. F.^*; Chen, Y. J.^*

来源：Orthopaedics & Traumatology-Surgery & Research, 2018, 104(1): 71-77.

DOI：10.1016/j.otsr.2017.10.013

• Safe zone
• Radial head
• CT
• Location

Purpose: Direct location of the "safe zone" on a CT axial view is impossible because the radial head is circular in shape. Previous "safe zone" location methods are not appropriate if the physician is unable to visualize the actual radial head. This study aims to introduce a new method to locate the "safe zone" on CT.
Methods: CT scans were performed on 20 intact cadaveric upper limbs from 20 different corpses in full pronation and supination. The DICOM-format raw data were then re-sliced and analyzed in Mimics 17.0 (Materialise, Belgium). The radial interosseous border (IB) is shaped like a droplet on the axial view; its axis was selected as our reference line (RL). A parallel line in the radial head axial slice was created, and its position relative to the "safe zone" was studied. Deviation in RL direction was evaluated.
Results: Safe-zone scope was 114.41 degrees +/- 11.99. The rotation angle from the RL to the safe-zone's anterior and posterior border was 215.03 degrees degrees 5.99 and 100.62 degrees degrees 8.12, respectively. Rotation direction (clockwise or anti-clockwise) depended on relative radius-ulna position. The safe zone was located by determining these two borders. The reference line's direction was stable in the upper half of the IB; its distance to the radial head fovea was 77.33 degrees mm degrees 6.24.
Conclusions: The radial head "safe zone" can be located on CT axial view based on the upper half of the IB using this new method. The method is clinically applicable to determine whether postoperative elbow malrotation results from plate impingement.

• 出版日期2018-2
• 单位上海交通大学