Added clinical advantage of combining ultrasound with radiograph in assessing ankle injuries: Comparison with MRI

Objectives

To compare the diagnostic accuracy of ultrasound (US) and magnetic resonance imaging (MRI) for ankle ligament injuries, and evaluate ankle injury using the combination of US and X-ray.

Materials and methods

A retrospective study was conducted on 1419 participants presenting with ankle injury at hospital between July 2020 and March 2022. 1153 patients included after exclusion underwent US imaging, while 584 patients were also diagnosed by X-ray and 78 accepted MRI. The diagnostic abilities of MRI and US for ankle ligamentous injuries (anterior inferior tibiofibular ligament (AITFL), anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), medial deltoid ligament (MDL)) were compared by Wilcoxon signed-rank test. The diagnostic performance of US for ligamentous tear was evaluated in terms of sensitivity, specificity, and AUC value, with MRI as the reference standard. The detection rates of X-ray imaging, US imaging, and their combination were compared by Kendall's W test and Wilcoxon signed-rank test.

Results

The study population included 558 males and 595 females with a mean age of 30 ± 13 years. There were no significant differences on the grade of ligament injury detected by US and MRI (P _AITFL = 0.52, P _ATFL = 0.15, P _CAL = 0.061, P _MDL = 0.26). The diagnostic sensitivity, specificity and AUC of US imaging for ligamentous tear were 50.0 %, 88.9 % and 0.69 in AITFL, 92.7 %, 60.9 % and 0.77 in ATFL, 90.9 %, 86.6 % and 0.89 in CFL, 66.7 %, 96.0 % and 0.81 in MDL respectively. The detection rate of bone fracture increased significantly after combining US and X-ray imaging (R _{US & x-ray} = 42.6 %, R _US = 36.5 %, R _x-ray = 26.5 %, P < 0.0001).

Conclusion

US imaging showed similar diagnostic performance for AITFL, ATFL, CFL and MDL injury as MRI. The combination of US and X-ray imaging can be a useful complementary tool for primary evaluation of ankle injuries.