Can the ACL Cross-Sectional Area Be Predicted? Size Correlation and Proportion between the ACL Cross-Sectional Area and the Femoral Intercondylar Notch Area.

The purpose of this study was to reveal the correlation and proportion between the anterior cruciate ligament (ACL) cross-sectional area and the femoral intercondylar notch area. Sixty-three subjects (33 female and 30 male) less than 50 years old were included in this study. All subjects complained of knee pain, although magnetic resonance imaging (MRI) showed no structural damage of the knee. Using the T2 axial slice of the MRI perpendicular to the bone shaft, the ACL cross-sectional area and the femoral intercondylar notch area were measured. Measurements were made at the most proximal (S1), ⅓ (S2), ⅔ (S3), and the most distal (S4) Blumensaat's line levels. The correlation and the proportion between the ACL cross-sectional area and the notch area were calculated. The ACL cross-sectional area was: S1: 35.9 ± 10mm², S2: 59.9 ± 14mm², S3: 67.2 ± 19.5mm², and S4: 70.7 ± 20.3mm². The notch area was: S1: 215.5 ± 43mm², S2: 311.8 ± 65mm², S3: 453.8 ± 86mm², and S4: 503.7 ± 99.8mm². The ACL cross-sectional area and the notch area were found to be significantly correlated at the S3 (Pearson's coefficient correlation: 0.510, p = 0.000) and S4 (Pearson's coefficient correlation: 0.529, p = 0.000) levels. The proportion of the ACL cross-sectional area to the notch area was 15% in S3 and 14% in S4. The ACL cross-sectional area was found to be significantly correlated with the femoral intercondylar notch area at the distal level of the Blumensaat's line. The ACL cross-sectional area was found to be approximately 15% of the notch area. The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area. This finding can be useful for achieving greater accuracy in anatomical ACL reconstruction. LEVEL OF EVIDENCE:  III.