Sagittal femoral condyle morphology correlates with femoral tunnel length in anatomical single bundle ACL reconstruction

Development of an Original Three-Dimensional Computed Tomography Scan Method and Imaging Process for Surgical Support of the Anterior Cruciate Ligament

Three-dimensional computed tomography (3D CT) scan images are useful as they can provide information essential for surgical support, particularly in orthopedic surgery. In the case of anterior cruciate ligament (ACL) reconstruction, a 3D CT scan is important in preoperative simulation. Furthermore, it is associated with a reduced risk of revision surgery because the angle of the foramen magnum changes with the femoral muscle mass. However, the CT scan system geometry has several limitations. For example, the patient's posture is limited during the procedure. Herein, we report an original CT scan method and 3D imaging process for surgical support of the ACL.

The correlation between the femoral anterior cruciate ligament footprint area and the morphology of the distal femur: three-dimensional CT evaluation in cadaveric knees

BACKGROUNDS

"Anatomical" anterior cruciate ligament (ACL) reconstruction is defined as the functional restoration of the ACL to its native dimensions. It is essential to obtain more accurate predictors of ACL size before surgery. The purpose of this study was to investigate the correlation between the native femoral ACL footprint size and the morphology of the distal femur using three-dimensional CT (3D-CT).

METHODS

Thirty non-paired Japanese human cadaver knees were used. All soft tissues around the knee were resected except the ACL. For the evaluation of femoral condyle morphology, trans-epicondylar length (TEL), notch outlet length, axial notch area, and notch width index were measured using 3D-CT. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the boundaries of the ACL insertion site were outlined on the femoral side. An accurate lateral view of the femoral condyle was photographed with a digital camera. The size of the femoral ACL footprint, length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were measured with ImageJ software.

RESULTS

Notch height, lateral notch area, and TEL were significantly correlated with the femoral ACL footprint area. Both axial notch area and notch outlet length were significantly correlated with the femoral mid-substance insertion area.

CONCLUSION

Morphological evaluation using 3D-CT preoperatively may be useful in predicting the femoral ACL footprint size.

Evaluation of age-related differences in anterior cruciate ligament size

PURPOSE

The purpose of this study was to reveal the relation between age and the morphological characteristics of the anterior cruciate ligament (ACL) using magnetic resonance imaging (MRI).

METHODS

Thirty-seven young subjects who were diagnosed with a meniscus injury without ACL tear using MRI (15 male and 22 female, median age 26, range 15-49), and 33 elderly subjects for whom knee MRI was performed before uni-compartmental knee arthroplasty (11 male and 22 female, median age 77, range 60-83), were included in this study. In the elderly group, healthy ACL gross morphology was confirmed macroscopically during surgery. In all knees, ACL was detected without any intensity alteration. In the MRI evaluation, using the axial slice revealing the greatest length between the medial and lateral epicondyle of the femur, axial ACL size was evaluated. Using the coronal plane image, the sagittal image was sliced parallel with the native ACL. In the sagittal image of the MRI, the largest area of the ACL was measured. Statistical analysis was performed to reveal the correlation between age and ACL size. Both axial and sagittal ACL areas were compared between the young and elderly groups.

RESULTS

Age and sagittal ACL area were significantly correlated (Pearson's coefficient correlation: - 0.353, P = 0.003). The sagittal ACL area was significantly larger in the young group when compared with the elderly group (P = 0.001). However, when the sagittal ACL area was normalized by the length of Blumensaat's line, no significant difference was observed.

CONCLUSION

For clinical relevance, sagittal ACL size was significantly larger in young subjects. The reason for this difference is likely the difference in knee size. When performing anatomical studies of the ACL using cadaveric knees of elderly specimens, there is the possibility that the ACL size will be underestimated. Considering that the ACL surgery is mainly performed for young subjects, cadavers of younger age should be used in such studies.

LEVEL OF EVIDENCE

Diagnostic study, Level III.