Comparison of Barefoot Walking and Shod Walking Between Children with and Without Flat Feet

Background We sought to investigate the effect of wearing shoes on joint range of motion, ground reaction force (GRF), and muscle activity (electromyography) in children with flat and normal feet during walking. Methods Nine children with flat feet and 12 children with normal feet aged 5 to 11 years were recruited. Each child was instructed to walk on a walkway in the barefoot and shod conditions. Joint range of motion, GRF, and electromyographic data within one gait cycle were collected simultaneously. Two-way analysis of variance was performed to evaluate the effects of foot type and shoe condition on the response measures. Results Children with flat feet had greater joint motion and higher muscle activities in the lower extremity, as well as lower vertical GRF and longer duration of the first peak forces in vertical and mediolateral GRFs than children with normal feet while walking. Compared with the barefoot condition, shoe wearing in both groups of children showed an increase in ankle dorsiflexion at heel strike, a decrease in anteroposterior GRF and its duration, and an increase in leg muscle electromyographic activities. Pelvic tilt range of motion was affected by the interaction of foot type and shoe condition. Conclusions Gait performance in pelvic tilt, hip flexion, and ankle dorsiflexion were different between the two groups of children. Wearing shoes increased the muscle activities of the shin. This finding can provide important information for clinical assessment of and shoe design for children with flat feet.

Efficacy and Mechanism of Orthotic Devices to Unload Metatarsal Heads in People With Diabetes and a History of Plantar Ulcers

Background and Purpose. Total-contact inserts (TCIs) and metatarsal pads (MPs) frequently are prescribed to reduce excessive plantar stresses to help prevent skin breakdown in people with diabetes mellitus (DM) and peripheral neuropathy. The first purpose of this study was to determine the effect of a TCI and an MP on metatarsal head peak plantar pressures (PPP) and pressure-time integrals (PTI). The second purpose of this study was to determine a possible mechanism of pressure reduction by measuring contact area and loaded soft-tissue thickness (STT) under the metatarsal heads and second metatarsal shaft. Subjects. Twenty subjects (12 men and 8 women; age [mean±SD]=57±9 years) with DM (duration [mean±SD]=16±11 years), peripheral neuropathy, and a history of plantar ulcers participated. Methods. A repeated-measures research design was used, and outcome measures are reported for 3 footwear conditions: shoe, shoe with TCI, and shoe with TCI and MP. In-shoe plantar pressures were collected during walking and during spiral x-ray computed tomography (SXCT). The STT and identification of the pressure sensor and location of the MP in relationship to the metatarsal heads were determined by use of SXCT. Results. The PPP and the PTI were 16% to 24% lower at the metatarsal heads in the TCI condition than in the shoe condition. The PPP and the PTI decreased an additional 15% to 28% (for a total reduction of 29% to 47%) with the addition of the MP. The contact area increased 27% with the TCI but not with the MP. The STT did not increase under the metatarsal heads in the TCI condition (compared with the shoe condition) but did increase 8% to 22% at metatarsal heads 2 to 5 with the addition of the MP. The PPP increased substantially (308%) and the STT decreased 14% under the shaft of the second metatarsal with the addition of the MP to the TCI-plus-shoe condition. Discussion and Conclusion. The TCI and the MP caused substantial and additive reductions of pressures under the metatarsal heads. The TCI reduces excessive pressures at the metatarsal heads by increasing the contact area of weight-bearing forces. Conversely, the MP acts by compressing the soft tissues proximal to the metatarsal heads and relieving compression at the metatarsal heads. These findings can assist in the design of effective orthotic devices to relieve excessive plantar stresses that contribute to skin breakdown and subsequent amputation in people with DM and peripheral neuropathy. [Mueller MJ, Lott DJ, Hastings MK, et al. Efficacy and mechanism of orthotic devices to unload metatarsal heads in people with diabetes and a history of plantar ulcers. Phys Ther. 2006;86:833–842.]

Stiffness Adaptations in Shod Running

When mechanical parameters of running are measured, runners have to be accustomed to testing conditions. Nevertheless, habituated runners could still show slight evolutions of their patterns at the beginning of each new running bout. This study investigated runners' stiffness adjustments during shoe and barefoot running and stiffness evolutions of shoes. Twenty-two runners performed two 4-minute bouts at 3.61 m·s–1shod and barefoot after a 4-min warm-up period. Vertical and leg stiffness decreased during the shoe condition but remained stable in the barefoot condition,p< 0.001. Moreover, an impactor test showed that shoe stiffness increased significantly during the first 4 minutes,p< 0.001. Beyond the 4th minute, shoe properties remained stable. Even if runners were accustomed to the testing condition, as running pattern remained stable during barefoot running, they adjusted their leg and vertical stiffness during shoe running. Moreover, as measurements were taken after a 4-min warm-up period, it could be assumed that shoe properties were stable. Then the stiffness adjustment observed during shoe running might be due to further habituations of the runners to the shod condition. To conclude, it makes sense to run at least 4 minutes before taking measurements in order to avoid runners' stiffness alteration due to shoe property modifications. However, runners could still adapt to the shoe.

A Perturbation Study of Lower Extremity Motion during Running

The present study explored kinematic adaptation in the lower extremity to running in shoes with 10° valgus and varus midsole perturbations. Rearfoot motion and knee flexion/extension data on nine subjects were collected using a Selspot II system during treadmill running in the two test shoes and in a neutral shoe condition. Maximum pronation was significantly altered by an amount approximately the same as the shoe perturbation, but there was no substantial adaptation in the amount of knee flexion. From the rearfoot patterns it was inferred that time to maximum pronation may be an unreliable variable to describe the pattern of rearfoot motion; the two-phase profile using rearfoot velocity may be more useful. It was concluded that certain subtle sagittal plane kinematic adaptations in timing and velocity patterns did occur at the knee in response to the shoe perturbations.