Transfixing Screw Placement for Syndesmotic Injury

Category: Trauma Introduction/Purpose: The strategy of transfixing screw fixation including screw number, size, material, the number of cortex involved, and penetrating angle is controversial. The purpose of this fresh frozen cadaveric study is to demonstrate the optimal degree of transfixing screw insertion after syndesmotic reduction in the Pronation External Rotation (PER) type ankle fractures, and to study reliable parameters to evaluate the syndesmotic reduction. Methods: Twenty paired fresh frozen anatomic specimens of the ankles were obtained. Before dissection, CT scans were taken preoperatively. Then, preparation was performed by cutting and dissection of anterior interior tibiofibular ligament (AITFL), interosseous ligament and membrane. Two types of screw placement were set. Ten screws were inserted into right ankle at an angle of 25 to 30 degrees from neutral position. The other 10 screws were inserted into the left ankle at a 0 degree angle from neutral position. Postoperative CT scan was performed after screw insertion. Anterior fibular distance(AFD), posterior fibular distance(PFD), anterior translation distance(AT), diastasis, anterior-posterior translation(APT) were measured in 2D axial section and volume of the syndesmotic space were measured in 3D reconstruction data of preoperative and postoperative CT scan. Results: The transfixing screw fixation induce the significant difference in syndesmotic space regardless of insertion angle. There was significant difference only in fibular diastasis between both ankle model. There was no statistically significant difference in AFD, PFD, AT, APT and 3D reconstructed volume according to transfixing screw insertion angle when each measured value was compared through left and right ratio and absolute volume value. Conclusion: In ankle syndesmotic injury, transfixing screw insertion should be considered for the ankle stability. But, regardless of the insertion angle, transfixing screw insertion would have a significant therapeutic effect on ankle syndesmotic injury. Fibular diastasis would be the reliable parameters to evaluate syndesmotic reduction