Age-related differences in MRI signal intensity of the quadriceps and patellar tendons: Implications for ACL graft selection.

Purpose: To compare the thickness and magnetic resonance imaging (MRI) signal intensity at the patellar attachment of the quadriceps tendon (QT) and patellar tendon (PT) across age groups in order to evaluate age-related degenerative changes relevant to graft selection for anterior cruciate ligament (ACL) reconstruction. It was hypothesised that older groups would show increased signal intensity. Methods: Patients aged 14-65 years who underwent knee MRI were retrospectively reviewed. Participants were categorised into the senior (50-65 years), middle (30-49 years), young (20-29 years) and teen (14-19 years) groups. After propensity score matching for sex, height and weight, 64 participants were included in each age group. T2* sagittal MR images of the ACL graft harvest area were used to measure the tendon thickness and signal intensity. Results: QT was significantly thicker and had lower signal intensity than PT across all age groups. Thickness did not significantly differ between QT and PT across age groups. QT signal intensity was significantly higher in seniors than in young adults, whereas PT signal intensity was significantly higher in both middle-aged and senior groups than in the young group. Conclusions: The QT was thicker than the PT and exhibited a lower signal intensity across all age groups. Compared to the 20-29-year age group, signal intensity was higher in the 50-65-year age group for the QT and in the 30-65-year age group for the PT. These MRI-based findings suggest that the QT may offer advantages as a graft source, particularly in patients aged >30 years. Level of Evidence: Level III, cross-sectional study.