A dynamic study of the anterior cruciate ligament of the knee using an open MRI

Abstract

Recent anatomical and radiological studies of the anterior cruciate ligament (ACL) suggest the ACL length and orientation change during knee flexion, and an open MRI sequencing during knee flexion enables a dynamic ACL analysis. This study's goal is to describe a normal ACL using a 1T open MRI and, in particular, variations in length and insertion angles at different degrees of flexion. Twenty-one volunteers with clinically healthy knees received a dynamic MRI with their knees in hyperextension, neutral position, and flexed at 45° and 90° angles. For each position, two radiologists measured the ACL lengths and angles of the proximal insertion between the ACL's anterior edge and the roof of the inter-condylar notch. Additionally, we measured the ACL's and the tibial plateau's distal angle insertion between their anterior edges and then compared these with the nonparametric Wilcoxon test. The ACL had a significant extension between the 90° flexion and all other positions (hyperextension: 31.75 ± 2.5 mm, neutral position: 32.5 ± 2.6 mm, 45°: 35.6 ± 1.6 mm, 90°: 35.6 ± 1.6 mm). There was also a significant increase of the angle insertion between the proximal 90° flexion and all other positions, as well as between hyperextension and bending to 45° (hyperextension: 2.45° ± 3.7°, neutral: 13.4° ± 9.7°, 45°: 33 25 ± 9.3, 90: 51.85° ± 9.3°). Additionally, there is a significant increase in the distal angle insertion for all positions (hyperextension: 133.2° ± 5.4°, neutral position: 134.95° ± 4.4°, 45°: 138.35° ± 5.9°, 90°: 149.15° ± 8.6°). Our study is the first to exhibit that a dynamic MRI has a significant ACL extension in vivo during bending. This concept opens the way for further studies to improve the diagnosis of traumatic ACL injuries using a dynamic MRI.

Effects of Anteromedial Portal versus Transtibial ACL Tunnel Preparation on Contact Characteristics of the Graft and the Tibial Tunnel Aperture

“…The experimental setup was selected to isolate the effects of the tunnel drilling technique and has its limitations. This includes a static angle at which the load is applied, which does not fully replicate the changing bending angles of an ACL at the femoral and tibial apertures during flexion and extension 2534). While graft ruptures are more frequently found at the aperture of the femoral tunnel, any portion where the graft bends over a bony edge could be a source of graft failure.…”

A Retrospective Comparison of ACL Tear and Mucoid Degeneration MRI Findings and an Emphasis on Evaluating of ACL, Blumensaat, and PCL Angles

“…However, patients who had any suspicion of the ACL insufficiency at the physical examination in the hospital electronic medical records not included in the degeneration group. Another limitation is the knee joint position in the MRI examination, which can affect the angle measurements, as mentioned by Guenoun et al [29]. However, we routinely obtained all knee MRI examinations during full extension of the knee similar to most of the studies compared [3,7,10], but the position of the knee in the study by performed Mellado et al [11] was not exactly stated.…”

Computed Tomography Assessment of Anatomic Graft Placement After ACL Reconstruction: A Comparative Study of Grid and Angle Measurements

“…A study showed that the sagittal angle of the ACL ranges from 45° to 20° with increasing knee joint flexion. 16 This factor affects the measurements in a clinical setting, as even the slightest flexion during CT or MRI will change the angle of the ACL graft. Furthermore, even if the angle is correct, the placement may still be faulty if the graft is placed too anteriorly or too posteriorly.…”