Abstract
Category:
Ankle; Basic Sciences/Biologics
Introduction/Purpose:
The interosseous ligament (IOL) of the ankle, together with the anterior and posterior inferior tibiofibular ligament (ATFL and PITFL), are important structures which stabilizes the inferior tibiofibular joint. Besides securing the fibula tightly to tibia, these ligaments prevent excessive lateral fibular displacement and external talar rotation. Thus, any injury to either bone or ligaments at this level will result in instability and abnormal joint motion. Our study aims to evaluate the anatomical angle of the ankle interosseous ligament on magnetic resonance imaging (MRI) studies to better understand the biomechanical forces that act within the distal tibiofibular joint, relevance of assimilating the anatomical angle and its relevance in syndesmosis fixations.
Methods:
MRIs of ankles were chosen anonymously from the global PACS system database between the months September to October 2020. A total of 34 patients' MRIs were identified. Patients who sustained bone or soft tissue injury at the level of ankle syndesmosis were excluded to avoid any ambiguity in altered position of the IOL due to trauma. The angle of interosseous ligament from the tibial plafond was measured on the coronal plane. The axial plane was used as a reference to ensure correct position of measurement. This was done in collaboration with radiologists to ensure that IOL is correctly identified, prior to start of the study. The angle was measured separately by two different investigators and the average angle was obtained for each MRI. Data was tabulated and statistical analysis was done.
Results:
All of the 20 ankles identified during the study period were included in the analysis. There were 10 male and 10 female patients. Nine were left ankles and 11 were right ankles. The median age was 54 years (range 14 - 83). The mean IOL angle was
65.66 degrees. The standard error of difference between the 2 investigators was 0.567 and the two-tailed P value was 0.4980. By conventional criteria, this difference is considered to be not statistically significant.
Conclusion:
The ligament angle formed against tibial plafond bears theoretical relevance. We propose further cadaveric studies to confirm IOL anatomical ligament angle and carrying out implant failure stress test in a lab between the implant inserted parallel to the normal angle of IOL (65 degrees) vs 90 degrees. We also propose that such studies may show that all implants to stabilize the syndesmosis may be more effective if we try to reproduce nature by replicating as close to the IOL's anatomical angle rather than using a long held dogma of fixing syndesmosis to neutralize the forces as nature intended.