(1): The superficial and deep parts of the infrapatellar fat pat (IFP) have different morphological and functional characteristics. Knee pain often occurs during movement, and it is important to clarify the movement of the IFP during knee joint movement. The purpose of this study is to clarify that the movement of the superficial and deep parts of the IFP are different during knee extension in vivo using ultrasonography (US). (2): US was performed on 15 knees of 15 healthy adults. The probe was placed longitudinally at the center of the patellar tendon and the IFP was imaged. Measurements were taken during active extension of the knee from 90 degrees to 10 degrees of knee flexion at a rate of 30 times/min. The captured US videos were analyzed using Flow particle image velocimetry (Flow PIV) fluid measurement software. The region-of-interest (ROI) was set at the superficial part and the deep part of the IFP, and the flow velocity was calculated for each. (3): The flow velocity of the deep part (1.37 ± 0.13 cm/s) of the IFP was significantly faster than that of the superficial part (0.80 ± 0.23 cm/s). (4): Our results show that the flow velocity of the IFP is different between the superficial and deep parts and that US may be a better assessment tool for the movement of the IFP.

To elucidate the local microcirculation of the infrapatellar fat pad (IFP) in patients with knee osteoarthritis (KOA) by determining the changes in IFP hardness and hemoglobin concentration during isometric quadriceps exercise (IQE). In this observational cross-sectional study, patients diagnosed with bilateral KOA were included in the KOA group (30 knees), healthy older adults in the control group (20 knees), and younger adults in the young group (20 knees). Ultrasonography was performed at rest and during IQE to measure IFP hardness based on shear wave velocity. Near-infrared spectroscopy was performed to measure oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) in the IFP before (Baseline), during (IQE task), and after IQE (Post). IFP hardness and O2Hb, HHb, and cHb concentration were analyzed using a linear mixed model for the groups and measurement points. During IQE, IFP hardness changes were significantly less in the KOA group than in the other groups (KOA: 95% confidence intervals (CIs) [-0.854, 0.028]; control: 95% CI [-0.941, -0.341]; and young: 95% CI [-2.305, -1.706]). In the KOA group, O2Hb concentration exhibited no significant changes at Post compared with Baseline; however, significant changes were observed in the other groups (KOA: 95% CI [-1.176, 0.423]; control: 95% CI [-1.452, -0.276]; and young: 95% CI [-4.062, -2.102]). During IQE, changes in hardness and hemoglobin concentration in the IFP were not significant in the KOA group, suggesting impaired local microcirculation of the IFP.

The effects of radial extracorporeal shockwave therapy (rESWT) on piriformis syndrome were investigated using a single -case study design. This study used an AB single case with a follow-up phase design. The baseline phase consisted of general physical therapy, including piriformis stretching, while the experimental phase consisted of rESWT in addition to general physical therapy. A man in his 70s diagnosed with piriformis syndrome participated in the study. The Numerical Rating Scale (NRS) score, piriformis hardness, and cross-sectional area of the sciatic nerve were measured to determine the effectiveness of the intervention. The baseline and experimental phases were compared using a binomial distribution based on the celeration line. The NRS score, piriformis hardness, and cross-sectional area of the sciatic nerve were significantly decreased in the experimental phase compared to the baseline phase (NRS, p<0.001; piriformis hardness, p<0.001; cross-sectional area of the sciatic nerve, p<0.001). This effect was carried over to the follow-up phase for all variables. rESWT for piriformis syndrome improved the clinical symptoms, piriformis hardness, and cross-sectional area of the sciatic nerve. However, these results are exploratory and require further validation in future clinical trials.

Impaired subchondral bone perfusion contributes to bone marrow lesions (BMLs) in knee osteoarthritis (KOA); however, it has been assessed only under static and non-weight-bearing conditions. Dynamic, weight-bearing conditions such as walking may further compromise perfusion; therefore, understanding the resulting hemodynamics is crucial to the pathophysiology of BMLs; however, they remain unknown. This study characterized the hemodynamics of the medial aspect of the tibial tuberosity during walking in patients with KOA and BMLs using near-infrared spectroscopy (NIRS). In this cross-sectional study (March-July 2025), we compared the tibial hemodynamics during walking across four groups: young adults (n=18), older adults (n=18), KOA without BMLs (n=18), and KOA with BMLs (n=20). We used NIRS to measure changes in tissue oxygenation index (TOI) during a 3-min walking phase and a 5-min post-walking phase. BML volume was quantified using magnetic resonance imaging in the KOA-BML group only. Analysis of data from 74 participants revealed a significant group-by-phase interaction for all hemodynamic parameters using linear mixed models. Compared to the three control groups, the KOA-BML group showed a greater decrease in TOI (vs. young: MD -14.43, 95% CI [-17.30, -11.56]; vs. older adults: MD -11.94, 95% CI [-14.67, -9.21]; vs. KOA: MD -9.99, 95% CI [-12.73, -7.25]). Moreover, a lower TOI during walking correlated with a larger BML volume (r = -0.634, 95% CI [-0.840, -0.266]). Pathological hypoxia of the medial aspect of the tibial tuberosity during walking appears specific to patients with KOA-BMLs. This dynamic impairment correlates with BML volume.