Arthroscopic Evaluation of Subtle Syndesmotic Instability: Are We Pulling Correctly in the Coronal Plane?

Category: Ankle; Sports; Trauma Introduction/Purpose: While the lateral hook test (LHT) has been widely used to arthroscopically evaluate syndesmotic instability in the coronal plane, it is unclear whether the angulation of the applied force has any impact on the degree of instability. The aim of this study was to determine if changing the direction of the force applied while performing the LHT impacts the amount of coronal diastasis observed in purely ligamentous syndesmotic injuries. Methods: In 10 cadaveric specimens, arthroscopic evaluation of the distal tibiofibular joint in the coronal plane was performed. Anterior and posterior third coronal plane diastasis were assessed in the intact state and repeated after sequential transection of the, 1) anterior inferior tibiofibular ligament (AITFL), 2) the interosseous ligament (IOL) and the 3) posterior inferior tibiofibular ligament (PITFL). In all scenarios, the lateral hook test (LHT) was performed under 100N of laterally directed force. Additionally, LHT was also performed under 1) anterior inclination of 15 degrees and 2) posterior inclination of 15 degrees in the intact and AITFL+IOL deficient state. One-way ANOVA with post hoc Tukey HSD was used to test for significant differences in coronal plane measurements between each stage of ligament transection, and to determine the effect of different directions of force application on coronal space measurements in the intact and AITFL+IOL transected states. Results: Compared to the intact state, the distal tibiofibular joint remained stable after transection of AITFL under laterally directed force with no angulation. However, after additional transection of the IOL, the syndesmosis became unstable in the coronal plane (p = 0.029 and 0.025 for anterior and posterior third diastasis, respectively). This instability worsened further with subsequent transection of the PITFL (p =