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Radiographic landmarks for tunnel positioning in double-bundle ACL reconstructions
Sean D Pietrini1, Connor G Ziegler, Colin J Anderson
1Orthopaedic Biomechanics Lab, Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, USA.
Summary
This study identifies key radiographic landmarks for the anterior and posterior-medial (AM and PL) bundles of the anterior cruciate ligament (ACL). These findings provide a reliable method for locating ACL attachment sites on knee radiographs.
Area of Science:
- Orthopedic surgery
- Radiology
- Anatomy
Background:
- The anterior cruciate ligament (ACL) has two distinct bundles: the anteromedial (AM) and posterolateral (PL).
- Accurate identification of ACL bundle attachment sites is crucial for surgical reconstruction and understanding knee biomechanics.
- Current methods for locating these sites on radiographs can be variable.
Purpose of the Study:
- To establish quantitative and qualitative radiographic landmarks for the femoral and tibial attachment sites of the native ACL's AM and PL bundles.
- To assess the reproducibility of identifying these landmarks using intraclass correlation coefficients.
- To hypothesize that the radiographic positions of the AM and PL bundles can be defined relative to anatomic landmarks and radiographic reference lines.
Main Methods:
- Twelve cadaveric knees were utilized for the study.
- The femoral and tibial attachment sites of the AM and PL bundles were precisely labeled with radio-opaque markers.
- Three independent examiners quantified the positions of these attachment sites on standardized radiographs.
Main Results:
- On lateral femoral views, the AM bundle was located at 21.6% of the sagittal diameter along Blumensaat's line, and the PL bundle at 28.9%.
- On tibial AP views, the AM and PL bundles were positioned at 44.2% and 50.1% from the medial aspect along the coronal diameter, respectively.
- The center of the PL bundle attachment was found to be nearly at the center of the tibial plateau in both coronal and sagittal planes.
Conclusions:
- This study defines reliable radiographic locations for the femoral and tibial attachment sites of the native ACL's AM and PL bundles.
- A reproducible protocol for identifying these sites on radiographs using surrounding landmarks and reference lines has been established.
- The femoral attachments of the AM and PL bundles align horizontally at 115° of knee flexion, with the PL bundle tibial attachment centered on the tibia.