Diagnostic value of ultrasonography in acute lateral and syndesmotic ligamentous ankle injuries

OBJECTIVES: To determine the diagnostic value of ultrasonography for complete discontinuity of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the anterior inferior tibiofibular ligament (AITFL). METHODS: All acute ankle injuries in adult athletes (> 18 years old) presenting to the outpatient department of a specialised Orthopaedic and Sports Medicine Hospital within 7 days post-injury were assessed for eligibility. Using ultrasonography, one musculoskeletal radiologist assessed the ATFL, CFL and AITFL for complete discontinuity. Dynamic ultrasound measurements of the tibiofibular distance (mm) in both ankles (injured and contralateral) were acquired in the neutral position (N), during maximal external rotation (Max ER), and maximal internal rotation (Max IR). MR imaging was used as a reference standard. RESULTS: Between October 2017 and July 2019, 92 acute ankle injuries were included. Ultrasound diagnosed complete discontinuity of the ATFL with 87% (CI 74–95%) sensitivity and 69% (CI 53–82%) specificity. Discontinuity of the CFL was diagnosed with 29% (CI 10–56%) sensitivity and 92% (CI 83–97%) specificity. Ultrasound diagnosed discontinuity of the AITFL with 100% (CI 74–100%) sensitivity and 100% (CI 95–100%) specificity. Of the dynamic measurements, the side-to-side difference in external rotation had the highest diagnostic value for complete discontinuity of the AITFL (sensitivity 82%, specificity 86%; cut-off 0.93 mm). CONCLUSIONS: Ultrasound has a good to excellent diagnostic value for complete discontinuity of the ATFL and AITFL. Therefore, ultrasound can be used to screen for injury of the ATFL and AITFL. Compared with ultrasound, dynamic ultrasound has inferior diagnostic value for complete discontinuity of the AITFL. KEY POINTS: • Ultrasound has a good to excellent diagnostic value for complete discontinuity of the anterior talofibular ligament (ATFL) and anterior inferior tibiofibular ligament (AITFL). • Ultrasound can be used to screen for injury of the ATFL and AITFL. • Compared with ultrasound, dynamic ultrasound has inferior diagnostic value for complete discontinuity of the AITFL. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00330-020-07305-7) contains supplementary material, which is available to authorized users.