Purpose: The anterolateral ligament (ALL) has been proposed as a secondary stabiliser of the knee against tibial internal rotation in anterior cruciate ligament (ACL)-injured knees. The deep lateral femoral notch sign (DLFNS) has been proposed as an indirect imaging marker of high-energy pivot-shift trauma in ACL-injured knees. This study investigates the association between ALL injury and magnetic resonance imaging (MRI) anterolateral rotatory instability signs—including DLFNS and medial and lateral-anterior tibial translation—in acute ACL injuries.

 

Methods: A cross-sectional study was conducted on 176 patients (aged 18–50) who underwent primary ACL reconstruction. Patients were stratified by MRI-based ALL status: injured and intact. Two observers independently assessed ALL injury. Primary outcomes were the presence of DLFNS (depth > 2 mm) and medial and lateral anterior tibial translation.

 

Results: ALL injury was identified in 40/176 (22.7%) of patients with acute ACL injury. Interobserver agreement for ALL injury assessment was substantial (κ = 0.715). DLFNS prevalence did not differ significantly between ALL-injured and intact groups (10/40 (25.0%) vs. 29/136 (21.3%); p = 0.623). No significant differences were found in medial or lateral anterior tibial translation between groups. On multivariable logistic regression, concomitant bone bruise was the only factor independently associated with ALL injury (adjusted odds ratio 2.192, 95% confidence interval [1.012–4.748]; p = 0.047), whereas no association was found with time to MRI or LFNS.

 

Conclusions: No direct association was found between ALL injury and MRI signs of anterolateral rotatory instability, and bone bruise was the only independent factor associated with ALL injury. This finding may be consistent with ALL injury occurring within a broader injury pattern, which may not be reliably captured by DLFNS alone. The significantly greater lateral than medial anterior tibial subluxation suggests increased tibial internal rotation in ACL-injured knees, independent of ALL injury status.

Level of Evidence: Level III, cross-sectional study.

 

Keywords: anterior cruciate ligament, anterior tibial translation, anterolateral ligament, anterolateral rotatory instability, deep lateral femoral notch sign, magnetic resonance imaging.