2025 ISAKOS Biennial Congress ePoster
A New Method For Accurately Predicting The Femoral ACL Footprint Using Bony Landmarks: A Cadaver Study
Takashi Kozu, MD, Tokyo JAPAN
Makoto Suruga, MD, Tokyo, 東京都 JAPAN
Takanori Iriuchishima, MD, PhD, Takasaki, Gunma JAPAN
Yoshiyuki Yahagi, MD,PhD, Tokyo JAPAN
Jin Sato, MD, Tokyo JAPAN
Hyunho Lee, MD, PhD, Tokyo JAPAN
Kazuyoshi Nakanishi, Prof., Tokyo, Please Select JAPAN
Tokyo General Hospital, Nakano-ku, Tokyo, JAPAN
FDA Status Not Applicable
Summary
For optimal bone tunnel placement during ACL reconstruction, creating the tunnel posterior to the R-line is recommended.
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Abstract
Introduction
The precise determination of bone tunnel position is crucial in anatomical anterior cruciate ligament (ACL) reconstruction. Previous studies have reported that the intercondylar ridge (ICR), a widely utilized intraoperative indicator, forms an average angle of 137° with the femoral bony axis and passes through 79% of Blumensaat's line (BL) from anterior edge (Farrow LD et al. AJSM 2008). This study aimed to validate the accuracy of the ACL femoral footprint predicted from these bony landmarks and to identify the optimal bony axis angle and position on the BL that best approximates the actual ACL femoral footprint.
Materials And Methods
Fifty formalin-fixed cadaveric knees (19 male, 31 female; mean age 82 years, range 53-98) were examined. Cases with severe osteoarthritis were excluded. The femur was bisected sagittally, and the femoral ACL footprint was marked and digitally photographed. Image analysis was performed using ImageJ (National Institute of Health) to measure the actual footprint area (A-footprint). The area of the lateral wall of femoral intercondylar notch (predicted footprint, P-footprint) posterior to the line forming a 137° angle with the femoral bony axis and passing through 79% of the BL from anterior edge was measured. The coverage of P-footprint to the A-footprint was calculated (P-footprint/A-footprint×100 %). In addition, the contact point between the BL and the A-footprint was defined as B-point, and the anterior contact point between the A-footprint and the cartilage edge was defined as C-point. The line passing through B-point and C-point was defined as the R-line. The distance (%) from the anterior end of the BL to crossing point with R-line was measured over the entire length of the BL. Then, the angle between the R-line and the bone axis was measured. The mean values obtained were used to calculate the modified predicted footprint (M-footprint), and its coverage of A-footprint was evaluated. Statistical analysis was performed using Wilcoxon's signed rank test with
Significance
level of 0.05.
Results
The mean coverage of the P-footprint was 71.8% (±9.6), and the B-point was located on 75.2% (±6.3) from anterior edge of BL. The R-line formed an angle of 133.1° (±7.8) with the femoral axis. The coverage of M-footprint calculated using these values was 84.85% (±7.16), which was significantly higher than P-footprint (P<0.001).
Discussion
The findings of this study suggest that the M-footprint method provides a more precise estimation of the ACL femoral footprint compared to the P-footprint method. For optimal bone tunnel placement during ACL reconstruction, creating the tunnel posterior to the R-line is recommended.