Three-Dimensional Magnetic Resonance Imaging for Guiding Tibial and Femoral Tunnel Position in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

Abstract

Background: Femoral and tibial tunnel malposition for anterior cruciate ligament (ACL) reconstruction (ACLR) is correlated with higher failure rate. Regardless of the surgical technique used to create ACL tunnels, significant mismatches between the native and reconstructed footprints exist. Purpose: To compare the position of tunnels created by a standard technique with the ones created based on preoperative 3-dimensional magnetic resonance imaging (3D MRI) measurements of the ACL anatomic footprint. Study Design: Controlled laboratory study. Methods: Using 3D MRI, the native ACL footprints were identified. Tunnels were created on 16 knees (8 cadavers) arthroscopically. On one knee of a matched pair, the tunnels were created based on 3D MRI measurements that were provided to the surgeon (roadmapped technique), while on the contralateral knee, the tunnels were created based on a standard anatomic ACLR technique. The technique was randomly assigned per set of knees. Postoperatively, the positions of the tunnels were measured using 3D MRI. Results: On the tibial side, the median distance between the center of the native and reconstructed ACL footprints in relation to the root of the anterior horn of the lateral meniscus medially was 1.7 ± 2.2 mm and 1.9 ± 2.8 mm for the standard and roadmapped techniques, respectively ( P = .442), while the median anteroposterior distance was 3.4 ± 2.4 mm and 2.5 ± 2.5 mm for the standard and roadmapped techniques, respectively ( P = .161). On the femoral side, the median distance in relation to the apex of the deep cartilage (ADC) distally was 0.9 ± 2.8 mm and 1.3 ± 2.1 mm for the standard and roadmapped techniques, respectively ( P = .195), while the median distance anteriorly from the ADC was 1.2 ± 1.3 mm and 4.6 ± 4.5 mm for the standard and roadmapped techniques, respectively ( P = .007). Conclusion: Providing precise radiological measurements of the ACL footprints does not improve the surgeon’s ability to position the tunnels. Future studies should continue to attempt to provide tools to improve the tunnel position in ACLR. Clinical Relevance: This cadaveric study indicates that despite the use of 3D MRI in understanding the ACL anatomy, re-creating the native ACL footprints remains a challenge.

Reliability of Anatomic Bony Landmark Localization of the ACL Femoral Footprint Using 3D MRI

“…10 It has also been demonstrated that providing femoral footprint coordinates does not improve the precision by which surgeons place the tunnels. 24 In conjunction with the result of the present study, we posit that future work should focus on the implementation of 3D navigation for femoral tunnel placement. This would, in theory, reduce errors introduced by reliance on coordinate measurements transferred from the imaging workstation to the operating room.…”

“…26 There is consensus that precise anatomic placement of the ACL femoral graft is of paramount importance in restoring the function and stability of the injured knee. [2][3][4]17,23,24 However, it is also well established that conventional arthroscopic methods of femoral graft localization are lacking with respect to accuracy. 6,13,25,30,37 Recent work has focused on the anatomic reconstruction of the femoral footprint using preoperative imaging as a guide, with various groups utilizing magnetic resonance imaging (MRI) and computed tomography (CT) for femoral footprint characterization.…”

“…There is consensus that precise anatomic placement of the ACL femoral graft is of paramount importance in restoring the function and stability of the injured knee. 2 –4,17,23,24 However, it is also well established that conventional arthroscopic methods of femoral graft localization are lacking with respect to accuracy. 6,13,25,30,37…”

Technology‐assisted anterior cruciate ligament reconstruction improves tunnel placement but leads to no change in clinical outcomes: a systematic review and meta‐analysis

“…However, the use of CT imaging is limited due to the risk of radiation exposure, which can be reduced with low‐dose CT protocols [41, 55]. Alternatively, pre‐operative MRI of the contralateral knee may also be used to locate the anatomic ACL insertion site [33, 46, 51]. But, both 3D‐CT and MRI are costly and may not be readily available.…”

Tunnel Management in Revision Anterior Cruciate Ligament Reconstruction: Current Concepts

“…Recently, 2D and 3D MRI have been used and validated for the evaluation of tunnel shape. 29,31,50 Although MRI may have potential to characterize tunnel size and position, special sequencing is required, and metal artifact may distort images. Nevertheless, advancements in MRI make it a promising emerging modality for comprehensive evaluation of bone tunnels after ACLR without the need for ionizing radiation.…”