Introduction
The anterolateral ligament (ALL) of the knee has been described as playing a leading role in anterolateral rotational stability; however, clinical evidence is currently lacking to support clear indications for lateral extra-articular procedures as an augmentation to ACL reconstruction.(ACL-R)
Objective
To evaluate, in ACL injuries, the association between visualization of ALL tears in magnetic resonance imaging (MRI) and failure of an isolated primary ACL-R
Hypothesis
Visualization of an ALL tear in MRI is associated with a higher rate of failure of isolated primary ACL-R.
Methods
Retrospective case-control study. Eighty-four patients (86 knees) with isolated primary ACL-R operated by the same surgical team with a complete imaging study where included, consisting of 43 knees with ACL reconstruction failure (cases) and 43 knees without it (controls). Patients with multi-ligamentary injuries, articular cartilage procedures and malalignment requiring correction were excluded.
A musculoskeletal radiologist blind to the study underwent a pilot screening of sensitivity and specificity for the visualization of ALL tears, according to thickness and signal of the ligament in MRI. Patients with ACL tear and under anesthesia pivot shift examination +++/+++ in which anterolateral plasty/reconstruction was performed were considered positive. Patients examined under anesthesia with a pivot shift -/+++ and without anterolateral plasty/reconstruction were considered negative.
Subsequently, the visualization of the ALL, presence of tears and degree of injury were evaluated in all patient’s images of the primary ACL injury.
The statistical analysis included logistic regression to calculate Odds Ratio (OR) between ALL tear and failure of the ACL-R.
A power of 80% and significance of 5% were considered.
Results
The sensitivity and specificity of the musculoskeletal radiologist for ALL tears was 67% and 63% respectively.
Of the 86 MRIs analyzed, it was possible to visualize part of the ALL in 100% of the patients and the entire ligament in 34,9%.
In case group (ACL-R failure) a 59% had an ALL tear on the MRI of the primary injury. In control group (without ACL-R failure) 26% presented an ALL tear on the MRI of the primary injury.
An ALL tear on MRI was significantly associated with an ACL-R failure with an OR of 2.4 (p=0.05).
Conclusions
The visualization of an ALL tear in MRI increases the rate of failure of an isolated primary ACL-R.