The uncertainty of predicting intact anterior cruciate ligament degeneration in terms of structural properties usingT2relaxometry in a human cadaveric model

The combination of healing anterior cruciate ligament (ACL) volume and the distributions ofT2*relaxation times within it have been shown to predict the biomechanical failure properties in a porcine model. This MR-based prediction model has not yet been used to assess ligament degeneration in the aging human knee. Using a set of 15 human cadaveric knees of varying ages, we obtained in situ MR measures of volume andT2*of the intact ACL and then related these MR variables to biomechanical outcomes (maximum and yield loads, linear stiffness) obtainedvia ex vivofailure testing. Using volume in conjunction with the medianT2*value, the multiple linear regression model did not predict maximum failure load for the intact human ACL;R2=0.23,p=0.200. Similar insignificant results were found for yield load and linear stiffness. Naturally restricted distributions of the intact ligament volume andT2*(demonstrated by the respectiveZ-scores) in an older cadaveric population were the likely reason for the insignificant results. These restricted distributions may negatively affect the ability to detect a correlation when one exists. Further research is necessary to understand the relationship of MRI variables and ligament degeneration. While this study failed to find a significant prediction of human biomechanical outcome using these MR variables, with further research, an MR-based approach may offer a tool to longitudinally assess changes in cruciate ligament degradation.