Regarding “Identification of Normal and Injured Anterolateral Ligaments of the Knee. A Systematic Review of Magnetic Resonance Imaging Studies”

We would like to commend the authors of the article“Identification of Normal and Injured AnterolateralLigaments of the Knee: A Systematic Review of Mag-netic Resonance Imaging Studies.”1We completelyagree with the mainfindings, which were that theliterature up until April 2018 (the end date of theliterature search) reported high variability in the ratesof identification of the anterolateral ligament (ALL),and also the rates of injury in anterior cruciate ligament(ACL)-deficient knees. Andrade et al.1highlighted thatthesefindings are a function of the heterogenous na-ture of studies with respect to the methods by whichinjury to the ALL was evaluated and described.However, an additional limiting factor is the difficultyin clearly delineating the complex and tightly confluentstructures around the lateral epicondyle. This anatom-ical arrangement is susceptible to the magnetic reso-nance imaging (MRI) phenomenon known as thepartial volume effect (when portions of several struc-tures are averaged together in a single slice), and thiscan result in impaired spatial resolution and erroneoussignal intensity.2Although we agree with the sugges-tion of Andrade et al.1that there has been a need forbetter definition and characterization of normal andinjured ALLs on MRI, including reporting of inter- andintraobserver reliability, considerable progress has beenmade in this regard since the end date of their literaturereview. In fact, in another recent systematic review,Puzzitiello et al.3concluded that ALL injuries can beidentified on MRI or ultrasound with high levels ofinter- and intraobserver reliability