Effect of different forefoot rocker radii on lower-limb joint biomechanics in healthy individuals

Effects of rocker-bottom shoes on the gait biomechanics of running and walking: A systematic review

BACKGROUND

There is growing evidence demonstrating the effectiveness of rocker-bottom shoes regarding repetitive mechanical stress on the musculoskeletal system during locomotion.

RESEARCH QUESTION

Is there any effect of rocker-bottom shoes on the lower extremity biomechanics during walking and running in healthy individuals?

METHODS

Databases including PubMed, Scopus, Web of Science, Embase, ProQuest, Cochrane, and CINAHL were searched from inception until March 2024. Twenty-six eligible studies that examined the effects of rocker-bottom shoes on gait parameters were included. The modified Downs & Black index was used to assess the methodological quality of the included studies.

RESULTS

Seventeen studies with rocker-bottom profiles at forefoot-only and nine studies with rearfoot-to-forefoot profiles were identified. Both forefoot-only (toe apex position between 30 % and 50 % and toe spring 30-50 mm/ toe rocker angle 7-30°) and rearfoot-to-forefoot (heel apex position between 18 % and 40 %, heel spring 20-40 mm, heel rocker angle 7-15°) rocker-bottom shoes were effective in redistributing plantar pressure from rearfoot to midfoot and forefoot regions. They also reduced peak dorsiflexion, peak plantar flexor moment, sagittal ankle ROM, and peak knee flexion compared to non-rocker shoes.

SIGNIFICANCE

Although rocker-bottom shoes appear effective in alleviating overuse injury via offloading forefoot plantar pressure and improving sagittal plane ankle kinematics and kinetics, caution should be taken regarding design specifications, particularly mass, thickness, and material properties of the rocker-bottom shoes.

How does orthotic walker boot design influence lower limb and trunk function during gait?

BACKGROUND

Undesirable lower limb gait deviations have previously been reported when wearing orthotic walker boots; therefore, there is a need to optimize orthotic walker boot designs to facilitate normal gait.

OBJECTIVE

This study explored the biomechanical effects of 2 designs of orthotic walker boot on the lower limb and trunk compared with usual footwear.

STUDY DESIGN

A repeated measures analysis of variance was used to evaluate selected kinematic and kinetic variables under different walking conditions.

METHODS

Sixteen healthy participants walked in 3 conditions using: Walker A (Airselect Elite, Enovis), Walker B (Townsend XLR8 Series Walker, Thuasne, France), and a usual shoe. A 10-camera motion analysis system and 4 force plates were used to collect kinematic and kinetic data.

RESULTS

Gait speed was significantly slower in both orthotic walker boots, and there was significantly decreased ankle range of motion, which is their primary function. Significant deviations in normal knee and hip kinematics and kinetics, shank-to-vertical angle, and pelvic and trunk movements were noted with both walker boots, with the greatest deviations from the shoe condition observed in Walker B. Recline and incline shank angular velocities showed the greatest differences in Walker B, which could be associated with adverse knee joint moments and a significantly greater perceived ease of walking in Walker A.

CONCLUSIONS

Orthotic walker boot design significantly affects walking mechanics. Orthotic walkers with greater forefoot rocker profiles and inclined vertical shank angles may at least partly mitigate known gait deviations when wearing orthotic walkers.

Can We Quantify the Benefits of "Super Spikes" in Track Running?

The recent and rapid developments in track spike innovation have been followed by a wave of record-breaking times and top performances. This has led many to question what role "super spikes" play in improving running performance. To date, the specific contributions of new innovations in footwear, including lightweight, resilient, and compliant midsole foam, altered geometry, and increased longitudinal bending stiffness, to track running performance are unknown. Based on current literature, we speculate about what advantages these features provide. Importantly, the effects of super spikes will vary based on several factors including the event (e.g., 100 m vs. 10,000 m) and the characteristics of the athlete wearing them. Further confounding our understanding of super spikes is the difficulty of testing them. Unlike marathon shoes, testing track spikes comes with a unique challenge of quantifying the metabolic energy demands of middle-distance running events, which are partly anaerobic. Quantifying the exact benefits from super spikes is difficult and we may need to rely on comparison of track performances pre- and post- the introduction of super spikes.

Effects of Longitudinal Bending Stiffness of forefoot rocker profile shoes on ankle kinematics and kinetics

INTRODUCTION

Rocker profile shoes with a proximally placed apex are currently one of the most prescribed shoe modifications for treatment and prevention of lower leg deficits. Three geometrical rocker design parameters apex position (AP), apex angle (AA) and rocker radius (RR) influence both plantar pressure redistribution and kinetic and kinematic alterations of the lower leg. In addition, longitudinal bending stiffness (LBS) of the outsole influences these parameters as well. This study aims to investigate the effects of the LBS in combination with different forefoot radii of rocker shoes on kinematics and kinetics of the lower limb.

METHODS

10 participants walked in standard shoes and six experimental shoe conditions with high and low LBS and three different forefoot rocker radii with the same (proximal) AP and AA. Lower extremity kinematics and kinetics were collected while walking on an instrumented treadmill at preferred walking speed and analysed with a repeated measures ANOVA and Statistical Parametric Mapping (SPM) (α = .05; post hoc α = .05/6).

RESULTS

SPM analyses revealed no significant differences for LBS and interaction LBS*RR for most research variables in terminal stance (ankle angle, ankle moment, ankle power, foot-to-horizontal angle, shank-to-vertical angle, external ankle moment, ground reaction force angle). A significant LBS effect was found for anterior-posterior position of the centre of pressure during pre-swing and peak ankle dorsiflexion angle. No relevant significant differences were found in spatio-temporal parameters and total work at the ankle between low and high LBS.

CONCLUSION

This study showed that longitudinal bending stiffness does not affect the biomechanical working mechanism of rocker profile shoes as long as toe plantarflexion is restricted. Providing that the forefoot rocker radius supports at least a normal foot-to-horizontal angle at toe-off, there is no reason to increase sole stiffness to change ankle kinematics and kinetics.

Effects of rocker radii with two longitudinal bending stiffnesses on plantar pressure distribution in the forefoot

INTRODUCTION

Outsole parameters of the shoe can be adapted to offload regions of pain or region of high pressures. Previous studies already showed reduced plantar pressures in the forefoot due to a proximally placed apex position and higher longitudinal bending stiffness (LBS). The aim of this study was to determine the effect of changes in rocker radii and high LBS on the plantar pressure profile during gait.

METHOD

10 participants walked in seven shoe conditions of which one control shoe and six rocker shoes with small, medium and large rocker radii and low and high longitudinal bending stiffness. Pedar in-shoe plantar pressure measuring system was used to quantify plantar pressures while walking on a treadmill at self-selected walking speed. Peak plantar pressure, maximum mean pressure and force-time integral were analyzed with Generalized Estimated Equation (GEE) and Tukey post hoc correction (α = .05).

RESULTS

Significantly lower plantar pressures were found in the first toe, toes 2-5, distal and proximal forefoot in all rocker shoe conditions as compared to the control shoe. Plantar pressures in the first toe and toes 2-5 were significantly lower in the small radius compared to medium and large radii. For the distal forefoot both small and medium radii significantly reduced plantar pressure compared to large radii. Low LBS reduced plantar pressure at the first toe significantly compared to high LBS independent of the rocker radius. Plantar pressures in the distal forefoot and toes 2-5 were lower in high LBS compared to low LBS.

CONCLUSION

Manipulation of the rocker radius and LBS can effectively reduce peak plantar pressures in the forefoot region during gait. In line with previous studies, we showed that depending on the exact target location for offloading, different combinations of rocker radius and LBS need to be adopted to maximize treatment effects.