Normal Magnetic Resonance Imaging Anatomy of the Anterolateral Knee Ligament with a T2/T1-Weighted 3-Dimensional Sequence: A Feasibility Study

Abstract

Purpose The anatomy of the lateral knee compartment has been recently further explored with description of the anterolateral knee ligament (ALL). The purpose of this study was to confirm the presence of ALL on cadaveric knees and to describe its normal anatomy in young healthy volunteers, utilizing a high-resolution 3-dimensional (3D) pulse sequence. Methods Dissection was performed on 9 cadaveric knees in order to confirm the presence of ALL. Conventional 2-dimensional sequences of 10 knees at 1.5 T and 10 knees at 3 T, with a slice thickness of 2-4 mm, were reviewed for the presence of ALL. A 3D T2/T1-weighted gradient echo sequence (constructive interference in steady state [CISS]), yielding in-plane resolution of 0.4 mm × 0.4 mm × 0.4 mm, was applied in 14 healthy volunteers (26 knees). All 3D images were manipulated using multiplanar reconstruction (MPR) and the presence and width of ALL were recorded. Results Cadaveric dissection disclosed the presence of ALL in 8 of 9 knees. Conventional knee MR imaging depicted ALL only on coronal images (18 of 20) whereas the CISS revealed ALL on 24 of 26 studied knees (92.3%). ALL has a mean thickness of 1.1 ± 0.27 mm measured on coronal MR images. Conclusions ALL can be thoroughly assessed in young healthy individuals with the use of high-resolution 3D MR imaging with MPR at 1.5 T.