Strength of suture-button fixation versus ligament reconstruction in syndesmotic injury: a biomechanical study.

PURPOSE: To compare the biomechanical characteristics of suture-button fixation versus ligament reconstruction using semitendinosus tendon autograft in treatment of syndesmotic injury in cadaver biomechanical study. METHODS: Eight matched pairs of human cadaveric lower-extremities were measured intact, then following simulated syndesmosis injury by cutting the anterior tibiofibular ligament (AITFL), the distal 15 cm of the interosseous membrane (IO), and the deltoid ligament. Thereafter, the syndesmotic injury was treated by suture-button fixation or ligament reconstruction. The semitendinosus tendon was harvested as a graft. Biomechanical testing was performed after the surgical fixation. The foot underwent rotation from neutral position to an external rotation at a rate of 5°/s to 12.5 Nm. The three-dimensional syndesmotic diastasis readings, final rotation torque, and rotational angle were recorded. RESULTS: No difference was found in fibular displacements between two groups. Moreover, no significant difference was found in final rotation torque (11.95 ± 1.03 VS 11.66 ± 1.18 Nm, P = 0.62) and rotation angle (43.61° ± 14.77° VS 40.93° ± 10.94°, P = 0.56) in the suture-button group and ligament reconstruction group. CONCLUSION: The stability of the suture-button fixation was equivalent to ligament reconstruction using semitendinosus tendon autograft in treatment of syndesmotic injury as determined with biomechanical testing. However, this study does not prove that one is advantageous over the other.

MRI Identification of the Fibular and Talus Position in Patients with Mechanical Ankle Instability.

Specific anatomic variations of the ankle mortise may be found in people with ankle instability. The purpose was to evaluate the fibular and talus position in subjects with mechanical ankle instability (MAI). In this study, MR images of 54 patients with MAI and 51 patients from the author's institution for reasons unrelated to ankle instability were reviewed. The position of the fibular in relation to the talus (axial malleolar index, AMI) and medial malleolus (intermalleolar index, IMI) were evaluated at the axial plane. Meanwhile, the rotation of the talus was measured and calculated using a new index, the Malleolar Talus Index (MTI), which is measured in relation to the medial malleolar. The results showed that the AMI in the MAI patients increased significantly when compared to that in the control group. However, there was no statistically significant difference in the IMI between instability and control groups. The MTI increased significantly in the MAI patients when compared to that in the control group. The conclusion was that the patients with MAI have more of an internally rotated talus than a variation of fibular position.