CME OnDemand: 2022 AOFAS Annual Meeting-Evaluation of Distal Tibiofibular Interosseous Ligament Angle and Its Relevance in Syndesmosis Fixation

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The study evaluated the anatomical angle of the distal tibiofibular interosseous ligament (IOL) and its relevance in syndesmosis fixation. The IOL, along with other ligaments, stabilizes the ankle joint and prevents excessive displacement and rotation. The aim of the study was to better understand the biomechanical forces within the joint and the importance of considering the anatomical angle in fixation procedures.<br /><br />MRIs of ankles were analyzed, and the average IOL angle was found to be 65.66 degrees. The IOL acts as a spring that transmits axial load to the fibula during weight bearing, allowing minor tibiofibular separation during ankle dorsiflexion. Screw breakage is a possible complication that occurs during weightbearing, especially when the screw is perpendicular to the fibula, leading to sheer stresses and pain at the syndesmosis.<br /><br />The study suggests that aligning the fixation device with the anatomical angle of the IOL may distribute forces more physiologically. The weightbearing force is vertical, and transmission of the force to the fibula occurs inferolaterally. The study also provides approximate forces transmitted with the device angled or perpendicular to the fibula.<br /><br />Some limitations of the study include potential measurement bias among investigators and the possibility that the MRIs analyzed may not represent "normal" ankles. The study recommends further cadaveric studies to confirm the IOL's anatomical angle and stress tests to compare fixation devices inserted at the normal angle versus parallel to the tibial plafond.<br /><br />In conclusion, understanding the anatomical angle of the distal tibiofibular interosseous ligament is crucial for successful syndesmosis fixation. Aligning the fixation device with the anatomical angle may help distribute forces more effectively and minimize complications such as screw breakage. Further research is needed to validate these findings and optimize fixation techniques.

Asset Subtitle

Jason Ong, Biju Benjamin, Enhsun Choi, Efstathios Drampalos, Turab Syed

Keywords

anatomical angle

distal tibiofibular interosseous ligament

syndesmosis fixation

ankle joint stabilization

biomechanical forces

fixation procedures

IOL angle

axial load transmission

screw breakage

physiological force distribution