On the variability of “flexion creases” in the distal plantar areas of newborns

The plantae of 83 male and 95 female healthy, full-term Caucasian newborns from Austria (gestational age 235–301 days) were photographed and the flexion creases in the distal part were examined. Analysis of the creases was done under four different aspects, the main evaluation based on a scheme of nine creases introduced by Schenk and Patzer (1959). Two transversal (No. 1 and No. 9) and three longitudinal (Nos. 3, 6, and 7) creases are always or predominantly present, a finding corresponding with the data of Schenk on 52 male and 48 female newborns from Germany. In addition, the nine plantar creases were evaluated according to six degrees of expression, and some typical crease combinations are shown. Bilateral and bisexual similarity prevails. The results of this study might serve investigations of different populations and of medical disorders.     

Plantar hypoesthesia alters time-to-boundary measures of postural control

Our purpose was to identify the effect of diminished plantar cutaneous sensation on time-to-boundary (TTB) measures of postural control during double and single limb quiet standing. Thirty-two healthy young adults underwent 10 min of ice immersion of the plantar aspect of the feet prior to balance testing. On a different day, the subjects did not receive this intervention prior to testing. A 2 × 2 vision (eyes open, eyes closed) by sensation (control, hypoesthesia) repeated measures design was used to analyze the TTB measures. In double limb stance, there were significant interactions between sensation and vision for the absolute TTB minimum and the mean of TTB minima in the anteroposterior (AP) direction. There was a significant increase in both measures after sensation was diminished with eyes closed compared to the control, but not with eyes open. In single limb stance, the TTB absolute minimum, the mean of TTB minima in the AP direction, and the standard deviation of TTB minima significantly increased with hypoesthesia regardless of vision. No significant differences were found in the medial–lateral (ML) direction for any of the TTB measures in double or single limb stance. Sensory information from the plantar cutaneous receptors appears to be most important in the maintenance of AP postural control.     

Reliability of two-point discrimination thresholds using a 4-2-1 stepping algorithm

Purpose: A 4-2-1 stepping algorithm reliably captures light touch thresholds but has not been used to assess two-point discrimination (TPD) thresholds. Therefore, the purpose of this investigation was to determine the intra- and inter-rater reliability of a 4-2-1 stepping algorithm at determining TPD thresholds.

Materials and methods: Fifteen healthy, physically active young adults were assessed twice over a 1-week period using digital calipers and a 4-2-1 stepping algorithm. TPD thresholds were assessed by an expert and a novice examiner at each time point. Reliability was assessed on the plantar surface of the foot at the head of the first and base of the fifth metatarsal.

Results: Three intra-rater intraclass correlation coefficient (ICC) values exceeded 0.75 and were interpreted as good. The inter-rater reliability was good with ICC values ranging from 0.76 to 0.93 at both sites during both test sessions.

Conclusions: The 4-2-1 stepping algorithm demonstrates good intra- and inter-tester reliability at determining TPD thresholds on the plantar surface of the foot at the head of the first and base of the fifth metatarsal in young healthy adults.     

Diseases of epidermal keratins and their linker proteins

Epidermal keratins, a diverse group of structural proteins, form intermediate filament networks responsible for the structural integrity of keratinocytes. The networks extend from the nucleus of the epidermal cells to the plasma membrane where the keratins attach to linker proteins which are part of desmosomal and hemidesmosomal attachment complexes. The expression of specific keratin genes is regulated by differentiation of the epidermal cells within the stratifying squamous epithelium. Progress in molecular characterization of the epidermal keratins and their linker proteins has formed the basis to identify mutations which are associated with distinct cutaneous manifestations in patients with genodermatoses. The precise phenotype of each disease apparently reflects the spatial level of expression of the mutated genes, as well as the types and positions of the mutations and their consequences at mRNA and protein levels. Identification of specific mutations in keratinization disorders has provided the basis for improved diagnosis and subclassification with prognostic implications and has formed the platform for prenatal testing and preimplantation genetic diagnosis. Finally, precise knowledge of the mutations is a prerequisite for development of gene therapy approaches to counteract, and potentially cure, these often devastating and currently intractable diseases.     

Finite element modelling of radial shock wave therapy for chronic plantar fasciitis

Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression–rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.     

Soleus activity in post-stroke subjects: Movement sequence from standing to sitting

Introduction. The beginning of the movement sequence from standing to sitting requires the modulation of plantar flexors activity, including the soleus muscle (SOL), to allow the forward translation of the tibia in relation to the foot, preserving its antigravity function.

Purpose. To analyze the SOL activity during the initial phase of standing to sitting in stroke subjects.

Methods. Two groups of ten subjects each participated in this study, one composed of healthy subjects and the other with subjects with a history of stroke. Electromyographic activity (EMGa) of SOL was analyzed in the ipsilateral (IPSI) and contralateral (CONTRA) limb to side lesion in stroke subjects, and in one limb in healthy subjects during the initial phase of standing to sitting. A force plate was used to identify the movement sequence phase.

Results. The mean values of SOL EMGa were higher in healthy subjects than the ones obtained in the IPSI and CONTRA limb in stroke subjects. Significant differences were only observed between the IPSI and healthy limb (p?=?0.035).

Conclusion. When compared to the healthy subjects, stroke subjects showed a decreased SOL EMGa in the IPSI limb, which suggests that therapeutic decisions must consider the need to promote a better postural control also in the IPSI limb.     

Image-based midsole insert design and the material effects on heel plantar pressure distribution during simulated walking loads

The primary objective of this paper is to study the use of medical image-based finite element (FE) modelling in subject-specific midsole design and optimisation for heel pressure reduction using a midsole plug under the calcaneus area (UCA). Plugs with different relative dimensions to the size of the calcaneus of the subject have been incorporated in the heel region of the midsole. The FE foot model was validated by comparing the numerically predicted plantar pressure with biomechanical tests conducted on the same subject. For each UCA midsole plug design, the effect of material properties and plug thicknesses on the plantar pressure distribution and peak pressure level during the heel strike phase of normal walking was systematically studied. The results showed that the UCA midsole insert could effectively modify the pressure distribution, and its effect is directly associated with the ratio of the plug dimension to the size of the calcaneus bone of the subject. A medium hardness plug with a size of 95% of the calcaneus has achieved the best performance for relieving the peak pressure in comparison with the pressure level for a solid midsole without a plug, whereas a smaller plug with a size of 65% of the calcaneus insert with a very soft material showed minimum beneficial effect for the pressure relief.     

The “Plantar Test” Apparatus (Ugo Basile Biological Apparatus), a Controlled Infrared Noxious Radiant Heat Stimulus for Precise Withdrawal Latency Measurement in the Rat,as a Tool for Humans?

In the present study, we precisely and automatically measured the withdrawal latency to noxious radiant heat application in unrestrained male rats and in human subjects of both sexes, by means of the “plantar test” apparatus (Ugo Basile Biological Apparatus). The infrared light stimulus of this tool was applied underneath the hindpaws of rats and the middle fingers of human subjects. With one right and one left stimulation every 10 min, we observed a decrease in latency over a 40-min testing period in rats; the latency reached a mean value of 5.08 ± 0.25 sec after 40 min with a 36-W stimulus, which corresponded to 46.5d`C. In pilot experiments, also performed on rats, we showed that the opiate morphine (10 mg/kg, i.p.) produced remarkable increases of the withdrawal latency only in “naive” animals (i.e., ones that had never experienced the plantar test stimulus) and not in animals “habituated” to it. Among humans, we noted gender differences, such as less sensitivity to the infrared noxious radiant heat for women, particularly during the menstrual period. A difference from rats was that there was no significant latency modification along the 40-min testing period for either women or men, with a mean latency of 5.61 ± 0.18 sec (47.5d`C) for the women and 4.39 ± 0.10 sec (45.5d`C) for the men. These data confirm the reliability of the plantar test in rats, and demonstrate the possible use of an infrared source in human subjects as a noxious heat stimulus; the withdrawal reaction to this stimulus is emphasized as a good index of nociception in humans     

Understanding the evolution of the windlass mechanism of the human foot from comparative anatomy: Insights,obstacles, and future directions

Humans stand alone from other primates in that we propel our bodies forward on a relatively stiff and arched foot and do so by employing an anatomical arrangement of bones and ligaments in the foot that can operate like a “windlass.” This is a significant evolutionary innovation, but it is currently unknown when during hominin evolution this mechanism developed and within what genera or species it originated. The presence of recently discovered fossils along with novel research in the past two decades have improved our understanding of foot mechanics in humans and other apes, making it possible to consider this question more fully. Here we review the main elements thought to be involved in the production of an effective, modern human‐like windlass mechanism. These elements are the triceps surae, plantar aponeurosis, medial longitudinal arch, and metatarsophalangeal joints. We discuss what is presently known about the evolution of these features and the challenges associated with identifying each of these specific components and/or their function in living and extinct primates for the purpose of predicting the presence of the windlass mechanism in our ancestors. In some cases we recommend alternative pathways for inferring foot mechanics and for testing the hypothesis that the windlass mechanism evolved to increase the speed and energetic efficiency of bipedal gait in hominins. Am J Phys Anthropol 156:1–10, 2015 © 2014 Wiley Periodicals, Inc.