Abstract
PurposeDisruption of the syndesmosis, the anterior-inferior tibiofibular ligament (AITFL), the posterior-inferior tibiofibular ligament (PITFL), and the interosseous membrane (IOM), leads to residual symptoms after an ankle injury. The objective of this study was to quantify tibiofibular joint motion with isolated AITFL- and complete syndesmotic injury and with syndesmotic screw vs. suture button repair compared to the intact ankle.MethodsNine fresh-frozen human cadaveric specimens (mean age 60 yrs.; range 38–73 yrs.) were tested using a six degree-of-freedom robotic testing system and three-dimensional tibiofibular motion was quantified using an optical tracking system. A 5 Nm inversion moment was applied to the ankle at 0°, 15°, and 30° plantarflexion, and 10° dorsiflexion. Outcome measures included fibular medial-lateral translation, anterior-posterior translation, and external rotation in each ankle state: 1) intact ankle, 2) AITFL transected (isolated AITFL injury), 3) AITFL, PITFL, and IOM transected (complete injury), 4) tricortical screw fixation, and 5) suture button repair.ResultsBoth isolated AITFL and complete injury caused significant increases in fibular posterior translation at 15° and 30° plantarflexion compared to the intact ankle (p < 0.05). Tricortical screw fixation restored the intact ankle tibiofibular kinematics in all planes. Suture button repair resulted in 3.7 mm, 3.8 mm, and 2.9 mm more posterior translation of the fibula compared to the intact ankle at 30° and 15° plantarflexion and 0° flexion, respectively (p < 0.05).ConclusionAnkle instability is similar after both isolated AITFL and complete syndesmosis injury and persists after suture button fixation in the sagittal plane in response an inversion stress. Sagittal instability with ankle inversion should be considered when treating patients with isolated AITFL syndesmosis injuries and after suture button fixation.Level of evidenceControlled laboratory study, Level V.
Highlights
Syndesmotic ankle injuries are a relatively common injury, reported in up to 18% of ankle sprains and 23% of all ankle fractures [14, 30]
Syndesmotic repair Significantly higher posterior translation of the fibula with suture button repair was found compared to the intact ankle at 30° and 15° plantarflexion, and 0° flexion (p < 0.05) (Fig. 4)
The most important findings of the present study were that both isolated anterior inferior tibiofibular ligament (AITFL) and complete syndesmosis injury significantly increased posterior translation of the fibula and suture button repair resulted in persistent syndesmotic instability compared to the intact ankle in response to inversion, especially in plantarflexion
Summary
Syndesmotic ankle injuries are a relatively common injury, reported in up to 18% of ankle sprains and 23% of all ankle fractures [14, 30]. Disruption of the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous membrane (IOM) is a predictor of worse outcomes after ankle injury [32]. Grade III injuries involve disruption of the complete syndesmosis complex, including the AITFL, PITFL, and IOM, and are usually treated surgically with either cortical screw or a suture button fixation [1]. Management of a grade II injury, which involves a complete isolated disruption of the AITFL, is more controversial with regard to the need for surgical fixation depending on the instability of the distal tibiofibular joint [18]. Though a previous study has shown that ankle instability with inversion stress is important to consider, this has not been commonly investigated since an external rotation stress to the ankle is the primary mechanism of syndesmosis injury [28]
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