2015 ISAKOS Biennial Congress ePoster #1001

New MRI Protocol for the Evaluation of the Anterolateral Ligament of the Knee

Koichi Muramatsu, MD, Nagoya JAPAN
Bertrand Sonnery-Cottet, MD, PhD, Lyon, Rhône FRANCE
Hiroki Watanabe, MD, Nagoya JAPAN
Kenta Yokosawa, RT, Nagoya, Aichi JAPAN
Yudo Hachiya, MD, PhD, Nagoya, Aichi JAPAN
Hachiya Orthopaedic Hospital, Nagoya, Aichi, JAPAN

FDA Status Not Applicable

Summary: We should discuss the ALL status using 3D-MRI.

Abstract:

Introduction

The lateral capsular ligament is one of the lateral structures in the knee, and it is known as a stabilizer of the internal rotation of the tibia since Ségond fracture was reported. There are also some articles that name it as the anterolateral ligament (ALL) recently. It is difficult to evaluate the status of the ALL preoperatively although having the ALL injury or not, may affect clinical results after anterior cruciate ligament (ACL) reconstruction.
Patients and methods:
In this study, we reviewed 84 knees that had anatomical ACL reconstructions between 2007 and 2012. The identification and the status of the ALL on preoperative routine MR images taken by 1.0T, 1.5T or 3.0T of MRI machine were evaluated. The identification rates of the ALL in normal volunteers' knees were also evaluated.

Results

The ALL visualized as the low signal band from the femoral lateral epicondyle to the middle third of the lateral tibial condyle was identified in 48.8% of the T1 images, in 61.9% of the T2* images, and in 59.5% of the fat-suppression images. Sorting the results by MRI machine type, it was identified in 48.4% of the T1 images, in 60.9% of the T2* images, and in 54.7% of the fat-suppression images using the 1.0T machine (n=64). As for the 1.5T machine (n=10), it was identified in 40.0%, in 60.0% and in 70.0%, respectively. As for the 3.0T machine (n=10), it was identified in 60.0%, in 70.0% and in 80.0%, respectively. In normal volunteers' knees, similar rates were also indicated on routine MR images, however, the ALL was identified in 100% on the 3D-T2 images. There was the finding of the loosened ALL in 26.9% and there was the finding of the hyper signal around the ALL in 10.4% on the fat-suppression images. There were no findings of Ségond fracture among them.

Discussion

Preoperative evaluation of the ALL status might be important in the future in order to improve our clinical results after ACL reconstruction. However, our routine MR images were not good enough for identifying the ALL. We suppose that visualization of the ALL is easy to be influenced by the resolution, the slice thickness and the slice angle because this ligament is thin and fine. Our study demonstrates that 3D-T2 images improve pre-operatively the identification rate of the ALL. Although it takes extra time in imaging, we can set the voluntary imaging section along the ALL. The preoperative evaluation of the ALL by the 3D-T2 images might be of help to determine the surgical plan for ACL injuries.