Two Different Knee Rotational Instabilities Occur With Anterior Cruciate Ligament and Anterolateral Ligament Injuries: A Robotic Study on Anterior Cruciate Ligament and Extra-articular Reconstructions in Restoring Rotational Stability

Editorial Commentary: When Biomechanics Apparently Conflicts With Clinical Practice: The Role of Translational Medicine Regarding Combined Anterior Cruciate Ligament and Lateral Knee Reconstruction

“…Findings from the study of Noyes et al 2 are in agreement with published studies performed by the same and other groups of researchers using a robotic apparatus apparently simulating a pivot shift. [3][4][5][6] However, they seem to conflict with other biomechanical studies performed in the past with older methods 7,8 and more recently with the aid of an even more sophisticated device, such as navigation, [9][10][11][12][13] as well as with several clinical studies reporting on favorable outcomes of ERs.…”

“…This hypothesis was first formulated by Terry et al 8 when they described the horseshoe-fashioned structure formed by the ACL and ITB. In this sense, it is not surprising that in an anatomically well tensioned reconstructed ACL, a secondary lesion of the ALL, as in the study of Noyes et al, 2 resulted in limited rotational instability, rendering the following ER ineffective or even harmful. However, as reported by the authors themselves in the introduction of their article, when a combined ACL and ALL tear is produced along with an explosive pivot shift, a simple ACL reconstruction is unable to restore native knee stability.…”

“…Another very important point highlighted by Noye et al 2 is the actual risk of overconstraint of the lateral reconstructions. Since the 1980s, when ERs were quite popular, this risk has been considered.…”

“…As suggested in their article, individual bony anatomy and ligamentous structure could also contribute to the susceptibility of the knee to ACL injury. Another important issue from this study is whether the actual clinical setting resulting from an ACL tear has been reliably reproduced in the laboratory by Noye et al 2 To analyze this aspect, we should consider the overall surgical anatomy of ACL tears and the resulting knee instability starting from the beginning: the initial injury.…”

“…However, we do not know to which extent each component (expressed in millimeters and degrees, respectively) concurs for a mild, moderate, or severe pivoting. On this view in an ACL-deficient knee, even a mild increase in internal rotation, such as that encountered by Noyes et al 2 by cutting the anterolateral ligament (ALL), could be mechanically sufficient to produce a clinically relevant phenomenon. As suggested in their article, individual bony anatomy and ligamentous structure could also contribute to the susceptibility of the knee to ACL injury.…”