Insufficient morphological changes in the infrapatellar fat pad during walking in patients who underwent anterior...

The infrapatellar fat pad (IFP) plays the knee joint's buffers capacity based on flexible morphological changes under mechanical stress. Patients who underwent anterior cruciate ligament (ACL) reconstruction have insufficient IFP flexibility; however, morphological change under mechanical stress is still unknown.

This study aimed to investigate the morphological change in IFP (ΔIFP) during walking and their correlation with mechanical stress in patients who underwent ACL reconstruction.

Nineteen patients who underwent primary ACL reconstruction using an ipsilateral hamstring tendon graft (ACL group) and 18 age-matched healthy volunteers (control group) were included in this study. A three-dimensional motion analysis system was used to evaluate knee flexion moment during walking. The IFP was evaluated using ultrasonography with motion analysis and recorded while walking in video mode. An IFP waveform was constructed using a sequence of IFP thicknesses on each image. In particular, the ΔIFP was shown as the difference in IFP between maximum and minimum values on the waveform.

The knee flexion moment in the ACL group was higher than that in the control group, whereas the ΔIFP was significantly lower in the ACL group. There was a significant correlation between ΔIFP and knee flexion moment in the control group, but not in the ACL group.

ACL reconstruction has insufficient flexible morphological changes of IFP, which it could decline the reaction to mechanical stress during walking.