Use of portable ultrasonography for the diagnosis of lateral ankle instability

Abstract

Portable ultrasonography is increasingly used to evaluate ankle stability at the point of care. This study aims to determine the correlation of portable‐ultrasonographic and fluoroscopic measurements of ankle laxity in a cadaveric ligament transection model of ankle ligament injury. We hypothesize that there is an association between portable‐ultrasonographic and fluoroscopic measurements when performing stress evaluation of lateral ankle instability. Eight fresh‐frozen below‐knee amputated cadaveric specimens with intact proximal fibula underwent ultrasound and fluoroscopic evaluation of the ankle during anterior drawer and talar tilt testing. The assessment was first performed with all lateral ankle ligaments intact and thereafter with sequential transection of the anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament. The anterior drawer test was performed with both 50N and 80N of force, and talar tilt test was performed with 1.7 Nm of torque. Correlations between (1) portable‐ultrasonographic and fluoroscopic measurements and (2) sequential transection of lateral ankle ligaments were evaluated using Spearman's rank correlations. The same statistical test was used to investigate the correlation between the ultrasonographic and the fluoroscopic measurements. The inter‐ and intra‐observer agreement was assessed using the intraclass correlation coefficient through a two‐way mixed‐effects model with absolute agreement. Portable‐ultrasonographic and fluoroscopic measurements increased as additional ligaments of the lateral ankle were transected (Spearman's rank correlation ranged from 0.74 to 0.81, 0.74 to 0.81, p‐values < 0.001). Strong positive correlations between ultrasonographic and fluoroscopic measurements were found during the lateral ankle stability evaluation using anterior drawer and talar tilt testing (Spearman's rank correlation ranged from 0.81 to 0.85, 0.81 to 0.85, p‐values < 0.001). Inter‐rater (0.99, 95% CI: 0.98–0.99) and intra‐rater reliability (0.97, 95% CI: 0.95–0.99) for the ultrasonographic measurements were substantial. In conclusion, there was a strong correlation found between ultrasonographic and fluoroscopic values measured during simulated anterior drawer and talar tilt test in a cadaveric ligament transection model. In this model, the portable‐ultrasonographic measurement was found to be reliable for repeated measurements of the talar translation and the lateral clear space distance. Based on these data, ultrasonography is likely to become a valuable point of care diagnostic tool due to its ability to readily and dynamically evaluate suspected lateral ankle instability. Clinical Significance: The use of dynamic stress ultrasound to assess the anterior translation of the talus and the lateral clear space distance appears to be a reliable and repeatable technique to evaluate lateral ankle stability with a radiation‐free, noninvasive, and low‐cost manner.

Does the contralateral healthy ankle of patient with ipsilateral mechanical lateral ankle laxity show greater lateral ankle laxity? Evaluation of the anterior talofibular ligament by stress ultrasonography

“…Stress ultrasonography (US) has been reported to be a reliable and useful tool for evaluating lateral ankle laxity [10,11]. It has been reported that the anterior talofibular ligament (ATFL) ratio, which is defined as a ratio of stress ATFL length to non-stress ATFL length, is a useful parameter to assess lateral ankle laxity by stress US [10,12,13].…”

Fluoroscopic Evaluation of the Role of Syndesmotic Injury in Lateral Ankle Instability in a Cadaver Model

“…All fluoroscopic images were obtained using a technique previously described by Saengsin et al 30 Two standardized loading conditions were created: (1) an anterior drawer test with 50 and 80 N of direct force to quantify anterior talar translation relative to the tibia (Figure 1) 30 and (2) a talar tilt test under 1.7 Nm of torque to measure the talar tilt angle and lateral clear space (the distance between the lateral talar process and tip of the fibula) (Figure 2). 30 Prior studies have highlighted that 30 to 60 N of force is sufficient when performing the anterior drawer test to evaluate ATFL injury; thus, a force of 50 N was used to measure anterior talar translation. 22,35,36 Similarly, prior cadaveric studies have reported the ultimate load to failure of an uninjured ATFL or CFL as ranging from 90 to 307 N 2,33,38 ; thus, a force of 80 N was used as the maximum amount of physiologic load to prevent plastic deformation or rupture.…”

“…In both loaded and unloaded states, the anterior talar translation, or the distance between the tibial axis and the center of the talus on lateral radiographs, was determined, and the difference in anterior talar translation between both loading states was calculated (Figure 1). 30 Similarly, in both loaded and unloaded states, the lateral clear space distance and the talar tilt angle were determined on the AP radiographs, and the difference in the lateral clear space distances and the talar tilt angles between both loading states was calculated (Figure 2). 30…”

“…30 Similarly, in both loaded and unloaded states, the lateral clear space distance and the talar tilt angle were determined on the AP radiographs, and the difference in the lateral clear space distances and the talar tilt angles between both loading states was calculated (Figure 2). 30…”

“…About 10% to 30% of the patients with acute ankle sprain go on to develop lateral ankle instability (LAI). 9,28,31 LAI is defined as presence of abnormal motion between talus and fibula resulting from ligamentous rupture or laxity after initial ankle sprain or as a result of multiple sprains, 6,30 by ligamentous rupture or laxity after an initial ankle sprain, or as a culmination of multiple sprains. In patients with LAI, surgical management is indicated because of persistence of symptoms and failure of nonoperative management.…”