Evaluation of age-related differences in anterior cruciate ligament size.

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). 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. 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. 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. Diagnostic study, Level III.