Application of a true lateral virtual radiograph from 3D-CT to identify the femoral reference point of the medial patellofemoral ligament

Abstract

Purpose The purpose of this study is two-fold: (1) to describe the femoral reference point of the medial patellofemoral ligament (MPFL) on a virtual true lateral radiograph reconstructed from a three-dimensional computed tomography (3D-CT) image and (2) to compare this point with that of patients without patellofemoral instability and with Schöttle's point. Methods A total of 26 consecutive patients (29 afected knees) with recurrent patellar dislocation (RPD), who underwent MPFL reconstruction were included in this study (4 males; 22 females; mean age, 24.0 years old). Using a true lateral 3DCT image, the MPFL femoral insertion was identiied and marked with a 2-mm circle, and this image was reconstructed as a virtual true lateral radiograph. Following Schöttle's method, the point of intersection was described by their anterior-posterior and proximal-distal positions. As a control population, 29 age-and gender-matched patients with anterior cruciate ligament (ACL) injuries were also analysed. ResultsThe points in RPD patients were located signiicantly posterior (-2.5 ± 2.3 mm, p < 0.01) to the line representing an extension of the posterior cortex of the femur and distal (− 6.9 ± 2.4 mm, p < 0.01) to the posterior origin of the medial femoral condyle compared with those in the control population. The mean reference point of RPD patients was located in a 3.8-mm posterior and 4.4-mm distal position compared with Schöttle's point. Conclusions An anatomical and radiographic femoral reference point of the MPFL on a true lateral virtual radiograph was described with our method. In patients with RPD, this reference point was identiied to be more posterior and distal to Schöttle's point. More anatomical and individualized MPFL reconstruction will be secured using our method. Level of evidence Level IV.

What Is the Maximum Tibial Tunnel Angle for Transtibial PCL Reconstruction? A Comparison Based on Virtual Radiographs, CT Images, and 3D Knee Models

“…Currently, there is no consensus regarding the most appropriate approach for PCL reconstruction. Previous studies used the anterolateral approach to reduce the killer turn on the coronal plane [8, 10]. In our study, we increased the tunnel angle to reduce the killer turn on the sagittal plane.…”

“…We used CT images to create virtual radiographs, which do not present the shadow of soft tissue surrounding the knee, making them somewhat different from actual plain radiographs. However, virtual radiographs have been confirmed to be a valid alternative to plain radiographs [3, 10]. Second, this was a single-center study, and the included population is of Chinese Han descent, which may not be representative of other populations globally.…”

“…Based on 3D knee models, we created a virtual true lateral knee radiograph (sufficient superimposition of the distal medial and lateral femoral condyles) by rotating the 3D knee, as described by Ishikawa et al [10]. We modified the transparency of the 3D knee model to 50% to better observe the position of the tibial tunnel (Fig.…”

The optimal tibial tunnel placement to maximize the graft bending angle in the transtibial posterior cruciate ligament reconstruction: a quantitative assessment in three-dimensional computed tomography model

“…In order to simplify the measurement, the midpoint of the ALB and PMB on the medial femoral condyle was defined as the PCL attachment center. In present study, to obtain the true lateral view of the femur, the 3D knee model was adjusted on the Rhinoceros 3D modeling software to strictly overlap the medial and lateral femoral condyles ( 10 , 16 ). The transparency of the knee model was adjusted to emerging the Blumensaat’s line on the lateral view ( Figure 2A ).…”

A Novel Technique of Arthroscopic Femoral Tunnel Placement during Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation

“…Three-dimensional CT scans are obtained within one week after surgery to evaluate the femoral tunnel positioning ( Figure 8 ) [ 8 ]. To assess the accuracy, Schöttle’s point is first identified as the reference point on 3D-CT according to a previously described method [ 8 , 23 ]. The distance between the center of the femoral tunnel and Schöttle’s point is measured.…”