gms | German Medical Science

Objectives: Syndesmotic injury is a common injury that could be missed and/or malreduced.

• Malreduction of the syndesmosis has been reported to directly affect the functional outcomes and accelerates ankle arthrosis.
• The disruption occurs usually in three planes with anteroposterior, lateral translation and fibular rotation and barely to be isolated.(image)
• Computed tomography (CT) scan is superior to plain radiography in detecting syndesmotic integrity postoperative especially in identifying rotation of the distal fibula; although, no clear consensus in literature has been reached on the best way to assess such integrity.
• More than ten methods have been used, including measurements of mediolateral translation, anteroposterior translation, and axial rotation of the fibula.

Purpose: Measure the incidence of syndesmotic malreduction in the three planes after screw fixation using 6 different measures on post operative CT scan.(images)

Methods: A retrospective series of 60 cases, 48 males and 12 Females, age 21-64(mean 33.63),all patients had postoperative CT bilateral. Measurment of the anterior distance, posterior distance, tibiofibular clear space, tibioFibular overlap and fibular rotation 1 cm above the joint line. any bilateral difference in translation more than 2 mm or in rotation more than 6.5 degrees was considered malreduction.

Results: The overall incidence of malreduction detected was 51.6%

The highest incidence of malreduction was in lateral translation >50% of patients followed by anteroposterior translation then rotation.(graphs)

The most senstive measure in our study was TFO (detected The most malreductions) followed by ATFI then Fibular rotation.

Our study showed that the syndesmotic mal-reduction is not uncommon(51.6%),this incidence fall within the range published in literature(16- 52%).However,there are large variability in the incidence of malreduction among studies which is mostly due to inconsistent measurement methods and definitions of malreduction. Our results also confirm that syndesmotic disruption is a tri-planer deformity for which accurate reduction is difficult to achieve and detect, though postoperative CT scan is highly valuable in detecting the integrity and accuracy of reduction. Additionally, further steps should be taken to reduce the incidence of mal-reduction detected by CT scan e.g intra-operative 3D scan which can be considered in further study.

Conclusion: Syndesmotic disruption is a tri-planer deformity for which accurate reduction is difficult to achieve and detect. Measurement of syndesmotic integrity made on comparative bilateral axial CT images is valuable to detect any degree of malreduction which is not uncommon. The incidence of malreduction after sydesmotic screw may significantly vary depending on the definition of malreduction and the measurement method.