The Effects of Graft Size and Insertion Site Location During Anterior Cruciate Ligament Reconstruction on Intercondylar Notch Impingement

Intercondylar notch impingement is detrimental to the anterior cruciate ligament (ACL). Notchplasty is a preventative remodeling procedure performed on the intercondylar notch during ACL reconstruction (ACLR). This study investigates how ACL graft geometry and both tibial and femoral insertion site location affect ACL-intercondylar notch interactions post ACLR. A range of ACL graft sizes are reported during ACLR, from 6mm–11mm in diameter. Minor variability of up to 3mm in ACL insertion site locations is reported during ACLR. Several 3D finite element (FE) knee joint models were constructed using three ACL graft sizes and polar arrays of tibial and femoral insertion site locations. Each knee model was subjected to flexion, tibial external rotation, and valgus motion. Impingement force and contact area between the ACL and the intercondylar notch compared well with published cadaver study results. A 3mm shift in the antero-lateral direction of the tibial insertion site of the average and maximum size ACL increased impingement force by 155.4% and 242.9% respectively. A 3mm shift in the anterior-proximal direction of the femoral insertion site of the average and maximum size ACL increased impingement by 292.6%, and 346.2% respectively. Simulated notchplasties of 4mm and 5mm reduced graft impingement force by 89.4% and 100% respectively for the simulations with greatest impingement. For the kinematics applied, the results show that small differences in graft size and insertion site location may lead to large increases in impingement force and contact area. The study aims to improve ACLR success rates by understanding how minor variations in graft size and insertion site location affect intercondylar notch impingement. Because minor variations in insertion site location during ACLR are a known occurrence, the results of this study may support the argument for performing notchplasty during ACLR.