Diagnostic capability of dynamic ultrasound evaluation of supination-external rotation ankle injuries: a cadaveric study

Abstract

BackgroundAnkle syndesmosis injuries are common and range in severity from subclinical to grossly unstable. Definitive diagnosis of these injuries can be made with plain film radiographs, but are often missed when severity or image quality is low. Computed tomography (CT) and magnetic resonance imaging (MRI) can provide definitive diagnosis, but are costly and introduce the patient to radiation when CT is used. Ultrasonography may circumvent many of these disadvantages by being inexpensive, efficient, and able to detect injuries without radiation exposure. The purpose of this study was to evaluate the ability of ultrasonography to detect early stage supination-external rotation (SER) ankle syndesmosis injuries with a dynamic external rotational stress test.MethodsNine, all male, fresh frozen specimens were secured to an ankle rig and stress tested to 10 Nm of external rotational torque with ultrasonography at the tibiofibular clear space. The ankles were subjected to syndesmosis ligament sectioning and repeat stress measurements of the tibiofibular clear space at peak torque. Stress tests and measurements were repeated three times and averaged and analyzed using a repeated one-way analysis of variance (ANOVA). There were six ankle injury states examined including: Intact State, 75% of AITFL Cut, 100% of AITFL Cut, Fibula FX - Cut 8 cm proximal, 75% PITFL Cut, and 100% PITFL Cut.ResultsDynamic external rotation stress evaluation using ultrasonography was able to detect a significant difference between the uninjured ankle with a tibiofibular clear space of 4.5 mm and the stage 1 complete injured ankle with a clear space of 6.0 mm (P < .02). Additionally, this method was able to detect significant differences between the uninjured ankle and the stage 2–4 injury states.ConclusionDynamic external rotational stress evaluation using ultrasonography was able to detect stage 1 Lauge-Hansen SER injuries with statistical significance and corroborates criteria for diagnosing a syndesmosis injury at ≥6.0 mm of tibiofibular clear space widening.

Syndesmotic instability can be assessed by measuring the distance between the tibia and the fibula using an ultrasound without stress: a cadaver study

“…This modality allows evaluation of dynamic movements of the fibula, and physiological fibular movements can be evaluated by US even in the normal ankle [ 11 ]. As for the evaluation of syndesmosis instability, a method of measuring tibiofibular distance by US has been reported (as applied in this study) [ 13 ]. In that cadaveric experiment, distance between the tibia and fibula was quantitatively evaluated by adding external rotation stress.…”

“…Since quantitative evaluations can be performed with US, syndesmotic instability could be evaluated by measuring the distance between the tibia and fibula. Evaluation under loading with external rotation stress has been reported, but results under other stresses remain unknown [ 13 ]. In addition, applying stress loads to acute syndesmosis injuries remains unsafe because of the invasiveness to patients.…”

Ankle stability in ankle fracture

“…11 More recently, Fisher et al have reported that dynamic external rotation stress evaluation using ultrasonography was able to detect a significant difference between the uninjured ankle with a tibiofibular clear space of 4.5 mm and the stage 1 complete injured ankle with a clear space of 6.0 mm. 33 In the future, the increase in access to Weight-Bearing Computed Tomography may improve our diagnostic capability of ankle instability. Patel et al, have already published their work defining the reference values of the normal tibiofibular syndesmosis using the weight bearing CT, which will be useful when this modality becomes more widely available.…”

Portable dynamic ultrasonography is a useful tool for the evaluation of suspected syndesmotic instability: a cadaveric study

“…As a consequence, no consensus has yet been reached on the definition of clinically consequential syndesmotic instability. Ultrasonography is increasingly used in the diagnosis of syndesmotic instability as it allows for a bilateral dynamic evaluation of the ankle joint at the point of care with little risk to the patient and at low cost [ 1 , 13 , 18 , 32 ].…”