Femoral dense insertion of the anterior cruciate ligament with relation to femoral tunnel placement: a 3-D magnetic resonance imaging study / 中华创伤骨科杂志

ABSTRACT

Objective:To characterize the femoral dense insertion (FDI) of the anterior cruciate ligament (ACL) using 3D magnetic resonance imaging (MRI) so as to guide the femoral tunnel placement in ACL reconstruction.Methods:The 3D MRI data of the contralateral healthy knees were collected from 20 young and middle-aged patients who had been followed up for 2 years at the Department of Sports Medicine, Peking University Third Hospital from June to October 2019 after ACL reconstruction. There were 10 males and 10 females with an age of (34.5±7.8) years. The 3D models of FDI of ACL, as well as of the lateral femoral condyle and its cartilage were reconstructed using Mimics 15.01. The heights and front and rear positions of anteromedial (AM) bundle, center, and posterolateral (PL) bundle of FDI were measured with reference to the apex of deep cartilage (ADC), the deep cortical border of the lateral condyle, and the shallow and inferior cartilage margins.Results:In 3D MRI models, dense fibers of ACL femoral insertion were near the shallow and inferior cartilage margins to the shallow side, and extended obliquely deep and superior toward the over-the-top (OTP) in a band-like shape. The oblique angle was 12.5°. The AM bundle, FDI center, and PL bundle were all higher than ADC, being (4.5±0.7) mm, (3.5±0.8) mm and (2.2±0.6) mm away from ADC, respectively. The median distances to the deep cortical border of the lateral condyle and the shallow cartilage margin were (6.9±1.2) mm and (16.4±1.8) mm for the AM bundle, (11.0±1.4) and (12.1±1.6) mm for the FDI center, and (14.9±1.8) mm and (8.0±1.3) mm for the PL bundle.Conclusions:Dense fibers of ACL femoral insertion are near the shallow and inferior cartilage margin to the shallow side, and extend obliquely deep and superior toward the OTP in a band-like shape. As the height and depth measurements of the FDI in 3D MRI models supplement to the anatomy of ACL femoral insertion, they could be used to guide femoral tunnel placement in ACL reconstruction.