Reduction of olecranon fractures with no or minimal dorsal cortex comminution based on the contour of the posterior ulnar cortex: does it restore the greater sigmoid notch?

Abstract

When treating olecranon fractures surgically, surgeons rely on the contour of the posterior cortex of the proximal ulna. However, it is unclear whether the greater sigmoid notch (GSN) is restored anatomically by this method. We analyzed whether reduction of fractures based on the posterior ulnar cortex contour is reliable for restoration of the GSN contour in displaced olecranon fractures with no or minimal dorsal cortex comminution. We performed a retrospective review of 23 patients with Mayo type 2 olecranon fractures with no or minimal dorsal cortex comminution who were treated surgically. We analyzed pre- and postoperative elbow CT images and measured the interfragmentary distance (IFD), articular step-off, articular gap, contour defect and GSN angle to evaluate the restoration of the GSN contour. The mean preoperative IFD and contour defect were 16.5 mm (range 4.3-35.6 mm) and 4.3 mm (range 0.7-13.3 mm), respectively. Postoperatively, there was no residual IFD, and the mean contour defect decreased significantly to 1.4 mm (range 0-3.7 mm). The residual articular step-off and gap were 0.2 mm (range 0-3.8 mm) and 1.0 mm (range 0-5.9 mm), respectively. Acceptable GSN restoration was achieved in 14 of 23 patients (60.9%). Sixteen patients had > 2 mm of preoperative contour defect, and 7 (43.8%) achieved acceptable GSN restoration; the remaining 7 patients (100%) who had < 2 mm of the contour defect achieved acceptable GSN restoration. Patients whose preoperative contour defect was > 2 mm had a higher risk of unacceptable GSN restoration, with an odds ratio of 2.29 (p = 0.019). In displaced olecranon fractures without significant dorsal cortex comminution, reduction based on the posterior ulnar cortex could be reliable for fractures with under 2 mm of preoperative contour defect, but not for those with > 2 mm of contour defect. IV.