Dynamics of Tibiofibular Syndesmosis in Correlation with the Level of the Syndesmotic Scress in Maisonneuvre Fractures of the Ankle – a Cadaver Study

Background:

The objective of this study was to determine the level of the syndesmotic screw, the number of screws needed, and whether one or both cortices of tibia should be engaged to closely reproduce the physiological stability and elastic of the ankle mortise in syndesmotic rupture after Maisonneuve fractures.

Material and Methods: Twelve fresh frozen cadaveric pairs of lower extremities were used for this study. The knee was exarticulated and soft tisue removed leaving the lateral and medial ankle ligaments intact. The tibiofibular syndesmosis was then sharply sectioned. All specimens were mounted in an Instron 2000 material testing machine. An axial loading of 500 N was applied. Syndesmotic diastasis was measured by a linear transducer system. The specimens were divided into three groups. In group I, the specimens were instrumented with one syndesmotic screw 2.5 cm above tibia plafond. In group II, the same procedure was performed as in group I with the syndesmotic screw positioned 4 cm above tibia plafond. In group III, the syndesmosis was fixed in each pair with two screws 2.5 and 4 cm above tibia plafond. In all groups, the screws were positioned randomly through three cortices on the one side and through four cortices on the contralateral side.

Results: Significant difference was observed between the application of one or two screws through three or four cortical shells on one side and the level of the screw on the other.

Conclusions: According to the results of this study, we recommend to use one screw through four cortices 2.5 cm above the tibia plafond.