Cadaveric analysis of plantar fascia strain and the development of a plantar fascia stretching device.

Abstract

Plantar fasciitis is the most common cause of heel pain in adults, affecting 10 percent of individuals over their lifetime. Therapeutic stretching remains a cornerstone of conservative management, particularly plantar fascia-specific stretching, combining dorsiflexion of the ankle and toes with targeted digital pressure along the plantar aponeurosis. However, many patients cannot perform these techniques effectively due to limited mobility, age-related restrictions, higher body mass, or improper application of the exercises. This study characterizes the mechanical environment created during plantar fascia-specific stretching and assesses whether a custom-built stretching device could replicate the strain generated by manual techniques. Twelve morphologically normal cadaveric feet were dissected, and the plantar fascia was exposed. Strain sensors were affixed along the fascia, and deformation was measured under various conditions: resting baseline, great toe and lesser toes dorsiflexion with and without direct manual pressure, and application of a custom device with incrementally increased weights to load the plantar fascia. The results demonstrated that dorsiflexion of the metatarsophalangeal joints combined with direct pressure to the plantar fascia reliably produced measurable strain, whereas dorsiflexion alone did not consistently generate adequate strain. Great toe dorsiflexion was not required to induce effective plantar fascia strain when direct pressure was applied. The custom device reproduced the strain levels achieved with manual stretching, but only when configured to deliver targeted pressure at the fascia. These findings suggest that plantar fascia stretch is influenced by both metatarsophalangeal dorsiflexion and direct aponeurosis pressure, and that a properly designed device can replicate clinically relevant strain patterns.