Ultrasonography imaging of the anterolateral ligament using real-time virtual sonography

Background: The anterolateral ligament (ALL) functions as a stabilizer in the internal rotation of the knee. Previous studies have reported the ALL can be identified using magnetic resonance imaging (MRI); however, there are no reports on using ultrasonography (US) for this purpose. Real-time virtual sonography (RVS) uses magnetic navigation and computer software for the synchronized display of real-time US and multiplanar reconstruction MRI images. This study investigated the ability of using US with RVS to evaluate the ALL.

Methods: Nine healthy subjects were enrolled. The Digital Imaging Communications in Medicine MRI dataset was loaded into the Hitachi Aloka Preirus, and US images were displayed on the same monitor. When the ALL was identified using MRI, the monitor was frozen to evaluate the ALL. The ALL was divided into the femoral, meniscal, and tibial portions. The portions and thickness of the ALLs and the lateral inferior genicular artery (LIGA), a landmark for the ALL, were evaluated.

Results: All portions of the ALL could be identified using MRI. Using US, the tibial portion of the ALL was detected in all subjects and the femoral portion was detected in seven subjects; however, the meniscal portions could not be identified. The average ALL thickness as measured by US was 1.3±0.1 mm and the LIGA was identified in all cases.

Conclusions: Most portions of the ALL can be identified using US. As most ALL injuries occur at the femoral or tibial portion, US may be useful as a diagnostic tool for ALL injury.

Level of evidence: 4.