Restricted morphological changes in infrapatellar fat pad during walking is revealed as a dynamics feature in symptomatic knee osteoarthritis.

Purpose: Knee osteoarthritis (OA) is symptomatic, especially in terms of motion during activities of daily living. The infrapatellar fat pad (IFP) has a buffering function, owing to morphological changes within the knee joint, whereas poor morphological change in the anterior space of the IFP is often observed in symptomatic knee OA. This study aimed to investigate the correlation between morphological changes in the anterior space of the IFP during walking and symptoms in patients with knee OA.

Methods: Twenty-six patients with knee OA (OA group) and 11 healthy volunteers (control group) participated in this study. Ultrasonography revealed the IFP thickness in the anterior space during static and dynamic evaluations in the supine and walking positions. The waveform of the IFP during walking was constructed with a continuance value of the IFP in video mode. Moreover, it identified the difference in IFP between maximum and minimum values on the waveform as morphological change in IFP (ΔIFP). A three-dimensional motion analysis system was used to calculate the kinetics and kinematics of walking. The OA group underwent clinical evaluation using the Knee Injury and Osteoarthritis Outcome Score (KOOS).

Results: ΔIFP in the OA group was smaller than that in the control group, whereas there was no significant difference in supine IFP thickness. Moreover, there was a significant positive correlation between ΔIFP and KOOS-pain in the knee OA group, but not in terms of other parameters of IFP, kinetics, and kinematics.

Conclusions: Patients with symptomatic knee OA exhibit restricted morphological change in IFP during walking.