Magnetic resonance imaging (MRI) was used to study shape, area, and volume changes of KFP between ankle plantarflexion and neutral positions. Although area in the saggital plane appeared to decrease on average by 10% (SD = 2.4%) between ankle plantarflexion and neutral positions, no obvious volume changes were detected as the area of KFP in the transverse plane increased from ankle plantarflexion to neutral positions by approximately 10.2% (SD = 2.14%), which indicates that KFP is a non-compressible tissue in-vivo. This, in addition to the existence of fibrosis in PW's tip, support hypotheses that PW can assist in load bearing within the AT enthesis organ. AT bends were observed in this study using US scanning, and were typically found when the ankle was flexed passively or actively against low loads (0-1 kg). AT kinds were found typically below the KFP anchorage to AT and only momentarily (max of 0.2s), suggesting KFP can reduce AT kinking during flexion.