Biomechanical effects of rocker shoes on plantar aponeurosis strain in patients with plantar fasciitis and healthy controls

Abstract

Plantar fasciitis is a frequently occurring overuse injury of the foot. Shoes with a stiff rocker profile are a commonly prescribed treatment modality used to alleviate complaints associated with plantar fasciitis. In rocker shoes the apex position was moved proximally as compared to normal shoes, limiting the progression of the ground reaction forces (GRF) and peak plantarflexion moments during gait. A stiff sole minimizes dorsiflexion of the toes. The aim of this study was to investigate whether the biomechanical effects of rocker shoes lead to minimization of plantar aponeurosis (PA) strain during gait in patients with plantar fasciitis and in healthy young adults. 8 patients with plantar fasciitis (1 male, 7 females; mean age 55.0 ± 8.4 years) and 8 healthy young adults (8 females; mean age 24.1 ± 1.6 years) participated in the study. Each participant walked for 1 minute on an instrumented treadmill while wearing consecutively in random order shoes with a normal apex position (61.2 ± 2.8% apex) with flexible insole (FN), normal apex position with stiff insole (SN), proximal apex position (56.1 ± 2.6% apex) with flexible insole (FR) and proximal apex position with stiff insole (SR). Marker position data of the foot and lower leg and GRF were recorded. An OpenSim foot model was used to compute the change in PA length based on changes in foot segment positions during gait. The changes in PA length due to increases in Achilles tendon forces were computed based on previous data of a cadaver study. PA strain computed from both methods was not statistically different between shoe conditions. Peak Achilles tendon force, peak first metatarsophalangeal (MTP1) joint angle and peak plantarflexion moment were significantly lower when walking with the rocker shoe with a proximal apex position and a stiff insole for all subjects (p<.05). Changes in Achilles tendon forces during gait accounted for 65 ± 2% of the total PA strain. Rocker shoes with a stiff insole reduce peak dorsiflexion angles of the toes and plantar flexion moments, but not PA strain because the effects of a proximal apex position and stiff insole do not occur at the same time, but independently affect PA strain at 80–90% and 90–100% of the stance phase. Rocker shoes with an apex position of ~56% are insufficient to significantly reduce peak PA strain values in patients with plantar fasciitis and healthy young adults.

The rocker-soled shoes change the kinematics and muscle contractions of the lower extremity during various functional movement

“…Rocker-soled shoes are such a design that has been functionally designed for walking and running. Previous studies have shown that these shoes can cause significant changes in lower extremity biomechanics [1][2][3][4][5] . MBT shoes (Masai Barefoot Technology, Switzerland), which were probably the first rocker-soled shoes, were invented by observing the walking patterns of the Masai people.…”

Biomechanical Aspects of Military Footwear Usage and their Relationship with Lower Extremity Overuse Injuries. Doctoral Thesis

“…). Furthermore, it has been reported that gait with common footwear reduces ankle stability(Ramanathan et al, 2011), increases plantar aponeurosis length(Lin et al, 2013), minimises peak Achilles tendon force, and reduces first metatarsophalangeal joint dorsiflexion angle(Greve et al, 2019). The gait with running footwear showed the same ankle dorsiflexion as the barefoot gait(Louey & Sangeux, 2016), while the gait with military boots demonstrated a restricted range of ankle mobility (Schulze et al, 2014).…”