 The medial patellofemoral ligament, or MPFL, is the primary medial stabilizer of the patella. The MPFL almost always tears during pateller dislocation. First-time dislocations are typically treated non-surgically, but recurrences are common. For these cases, and in the absence of other risk factors, surgical MPFL replacement is preferred. However, approximately one-quarter of surgical patients experience complications like knee pain and a restricted range of motion, largely due to errors in graft fixation. Errors that lead to graft tightening during knee flexion are particularly problematic. In a recent study, researchers sought to understand the physiological strain behavior of the native MPFL to inform better surgical graft placement. To do so, they performed dynamic CT scans of 115 knees from 63 healthy subjects during a flexion-extension flexion movement and used the scans to create knee joint models. They measured the MPFL length as the shortest wrapping path from the femoral-shodals point to three insertion points on the patella's supra-medial border, the proximal, central, and distal points. They then calculated the percent changes in MPFL length in relation to knee anatomical features. The proximal fiber was the longest in full extension and its median length decreased by up to 6% at 90 degrees of flexion. The median length of the central fiber decreased by 2.8% during flexion and no elongation was observed. In contrast, the median length of the distal fiber decreased slightly upon initial flexion but increased at deeper flexion angles. The median maximal length changes for the proximal, central, and distal patellar insertions were 4.6, 4.7, and 5.7 mm respectively. However, these values correlated only weekly or not at all with the tibial tuberosity trochlear groove distance, the Caetan-Dachamp's index, and the lateral trochlear inclination. Notably, the models did not consider the different MPFL attachment sites of individual patients. In addition, the models did not include soft tissue, so the exact paths of the MPFLs were not replicated. Furthermore, the MPFL length changes during this active flexion-extension flexion movement might not be representative of different activities during daily life. Nevertheless, the results reveal that the median length of the proximal MPFL continuously decreases during flexion, indicating slackening. In contrast, the median length of the distal MPFL increases at deeper flexion angles, indicating tightening. These findings suggest that in MPFL reconstruction techniques utilizing Schodl's point for femoral insertion, surgeons should avoid distal patellar insertion as distal insertion causes elongation that may increase the risk of overloading related complications.