Utility of three-dimensional proton density-weighted sequence MRI in knee for the assessment of Anterolateral complex in Anterior cruciate ligament injury

Objectives: To assess the proportion and pattern of injury of the anterolateral ligament (ALL) and the Kaplan fibre (KF) complex in knees with anterior cruciate ligament (ACL) injuries on MRI using three-dimensional (3D) proton density (PD) sequences.

Methods: A total of 88 patients having ACL injury were included in this cross-sectional study. 3D PD sequences were used to assess injury of ALL and the KF complex and were graded on a scale of 0 to 3. MR images were evaluated by two radiologists. Interobserver agreement was determined using Cohen Kappa.

Results: Femoral, meniscal, and tibial portions of ALL were visualized in 90.9%, 92%, and 94.3% of the study subjects, respectively. Proximal and distal KF were visualized in 92% and 93.2% of patients, respectively. Injury to ALL and KF was seen in 63.6% and 17% of the patients, respectively. Excellent interobserver agreement was noted for the identification and grading of ALL and KF complex injuries.

Conclusions: Oblique reformatted 3DPD MRI reliably detect ALC; however, ALL injury is better characterized than KF injury using this sequence.

Advances in knowledge: Given the potential role of anterolateral complex (ALC) in maintaining the rotational stability of the knee, ALC assessment using the 3D PD sequences and their oblique reformatted images should be incorporated as routine review area of the knee MRI, particularly in the setting of ACL tear.