Summary

The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area in skeletally immature patients.

Abstract

Introduction

Although the anterior cruciate ligament (ACL) injury in skeletally immature subjects is becoming major issue, its accurate morphology has not been well investigated. When native ACL size can be predicted by the measuring of knee bony morphology, more accurate anatomical ACL reconstruction can be performed in the skeletally immature subjects.　
The purpose of this study was to reveal the correlation and proportion between the ACL　cross-sectional area and the femoral intercondylar notch area in skeletally immature patients. The hypothesis of this study was that some size correlation would be found between the ACL mid-substance cross-sectional area and knee bony morphology.

Materials And Methods

Thirty-five adolescents (20 female and 15male, average age: 13.5±2.3) with open growth plates on knee radiographs between 2016 and 2024 were included in this study. All subjects presented with knee pain, although magnetic resonance imaging (MRI) showed no structural damage of the knee. The exclusion criteria were, age under seven, and history of knee surgery. The ACL cross-sectional area and the femoral intercondylar notch area were measured using T2 axial MRI slice perpendicular to the bone shaft. 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.

Results

The ACL cross sectional area was as follows: S1:24.7±6.9mm2, S2:36.0±8.9mm2, S3:48.5±11.7mm2, and S4: 57.5±13.6mm2. The notch area was as follows: S1: 205.9±53.2mm2, S2: 288.8±72.9mm2, S3: 384.0±82.6mm2, and S4:437.3±82.9mm2. The ACL cross-sectional area and the notch area were found to be significantly correlated at the S1(Pearson’s correlation coefficient: 0.757, p=0.000) and S2(Pearson’s correlation coefficient: 0.637, p=0.000), S3(Pearson’s correlation coefficient: 0.734, p=0.000), S4 (Pearson’s correlation coefficient: 0.758, p=0.000) levels. The ACL cross-sectional area was found to be significantly correlated with the femoral intercondylar notch are. The proportion of the ACL cross-sectional area to the notch area was 12.0% in S1 and 12.5% in S2, 12.6% in S3 and 13.2% in S4.

Conclusions

The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area in skeletally immature patients. This finding can be useful for achieving greater accuracy in anatomical ACL reconstruction.