Effects of plantar fascia release and the use of foot orthoses affect biomechanics of the medial longitudinal arch of the foot. A cadaveric study

ABSTRACT Objective To evaluate the effect of minimally invasive ultrasound-guided fascial release and a foot orthoses with first metatarsal head cut-out on the biomechanics of the medial longitudinal arch of the foot in cadaveric specimens. Design A cross-sectional study was designed (20 body-donors). Anthropometric measurements of the foot, foot posture index and the windlass test and force were measured in different conditions: unloaded, loaded position, with foot orthoses, after a 25% plantar fascia release and after a 50% release. Results For the anthropometric measurements of the foot, differences were found in foot length (p = 0.009), arch height (p < 0.001) and midfoot width (p = 0.019) when comparing the unloaded vs foot orthoses condition. When foot orthoses were compared with 25% plantar fascial release, differences were found in foot length (p = 0.014) and arch height (p < 0.001). In the comparation with 50% plantar fascial release, differences were found in the arch height (p < 0.001). A significant interaction between foot orthoses condition and grades was found in the arch height during the windlass test (p = 0.021). Conclusion The results indicate that the presence of foot orthoses leads to a significant increase in arch height compared to other conditions. Furthermore, when plantar fascia release is performed, the arch does not exhibit any signs of collapse.