Impact of foot pronation on postural stability: An observational study

Delayed center of mass feedback in elderly humans leads to greater muscle co-contraction and altered balance strategy under perturbed balance: A predictive musculoskeletal simulation study

Falls are one of the leading causes of non-disease death and injury in the elderly, often due to delayed sensory neural feedback essential for balance. This delay, challenging to measure or manipulate in human studies, necessitates exploration through neuromusculoskeletal modeling to reveal its intricate effects on balance. In this study, we developed a novel three-way muscle feedback control approach, including muscle length feedback, muscle force feedback, and enter of mass feedback, for balancing and investigated specifically the effects of center of mass feedback delay on elderly people's balance strategies. We conducted simulations of cyclic perturbed balance at different magnitudes ranging from 0 to 80 mm and with three center of mass feedback delays (100, 150 & 200 ms). The results reveal two key points: 1) Longer center of mass feedback delays resulted in increased muscle activations and co-contraction, 2) Prolonged center of mass feedback delays led to noticeable shifts in balance strategies during perturbed standing. Under low-amplitude perturbations, the ankle strategy was predominantly used, while higher amplitude disturbances saw more frequent employment of hip and knee strategies. Additionally, prolonged center of mass delays altered balance strategies across different phases of perturbation, with a noticeable increase in overall ankle strategy usage. These findings underline the adverse effects of prolonged feedback delays on an individual's stability, necessitating greater muscle co-contraction and balance strategy adjustment to maintain balance under perturbation. Our findings advocate for the development of training programs tailored to enhance balance reactions and mitigate muscle feedback delays within clinical or rehabilitation settings for fall prevention in elderly people.

Modification of Pronated Foot Posture after a Program of Therapeutic Exercises

Working on the intrinsic musculature of the foot has been shown to be effective in controlling pronation. However, the potential coadjuvant effect that involving other muscle groups might have on foot posture remains unknown. The aim was, therefore, to assess whether a 9-week intrinsic and extrinsic foot and core muscle strength program influenced foot posture in pronated subjects. The participants were 36 healthy adults with pronated feet that were randomly assigned to two groups. The experimental group (n = 18) performed a strengthening exercise protocol for 9 weeks (two sessions of 40 min per week), while the control group (n = 18) did not do these exercises. After 9 weeks, the foot posture index (FPI) scores of the two groups were analyzed to detect possible changes. The FPI at the baseline was 8.0 ± 1.5. After the 9 weeks, the experimental group showed significantly reduced FPI from 8.1 ± 1.7 to 6.4 ± 2.1 (p = 0.001), while the control group had the same score as pre-intervention (FPI 8 ± 1.2, p = 1.0). The FPI scores showed no significant differences by sex. Strengthening of the intrinsic and extrinsic foot and core muscles contributed to improving foot posture in adults, reducing their FPI by 1.66 points.

Does Plantar Pressure Distribution Influence the Lumbar Multifidus Muscle Thickness in Asymptomatic Individuals? A Preliminary Study

BACKGROUND

Atrophy can occur in the lumbar multifidus (LM) muscle quickly as a result of various musculoskeletal problems. Knowing factors influencing muscle thickness of the LM will provide important clues about lumbopelvic stability.

OBJECTIVES

Although there are several studies in the literature investigating the adverse effects of foot-ankle postural disorders on the lumbopelvic region, to our knowledge there has been no investigation of plantar pressure distribution (PPD) as a factor influencing muscle thickness of the LM. The aim of this study was to determine whether PPD could affect LM muscle thickness.

METHODS

This observational study consisted of 25 asymptomatic individuals. Ultrasonographic imaging was used to determine the thickness of the LM. All participants were subjected to PPD analysis using the Digital Biometry Scanning System and Milletrix software in 9 different plantar pressure zones. The Pearson product-moment correlation coefficients were used to examine the correlations between the LM muscle thickness and other variables. Stepwise multiple linear regression analysis was used to determine the variables with the greatest influence on LM muscle thickness.

RESULTS

Peak pressures of medial and lateral zones of the heel were the significant and independent factors influencing static LM thickness, with 39.5% of the variance; moreover, the peak pressures of heel medial and fourth metatarsal bone were the significant and independent factors influencing dynamic LM thickness, with 38.7% of the variance.

CONCLUSIONS

Plantar pressure distribution could be an important factor influencing LM thickness, although further research is required. Examining foot-ankle biomechanics may provide information about the stability of the LM.

Association between Foot Posture Asymmetry and Static Stability in Patients with Knee Osteoarthritis: A Case-Control Study

Background

Interlimb asymmetries are considered to be closely related to knee osteoarthritis (KOA), but foot posture asymmetries in patients with KOA are scarcely reported.

Objectives

We aimed to explore the asymmetrical difference in foot posture between the healthy adults and KOA patients and the relationship between foot posture asymmetry and static stability.

Methods

21 subjects suffering from KOA in the patient group (PG) and 21 healthy adults in the control group (CG) were included in this study. Foot postures on both feet were evaluated by using the foot posture index (FPI); subsequently, asymmetrical FPI scores between two feet were calculated for the two groups. Meanwhile, all the participants were tested with a standing on Dynamic and Static Balancing Instrument (Pro-kin 254P, TecnoBody Company, Italy) for bilateral stability assessment, and center of pressure (COP) parameters including sway length (SL, mm) and sway area (SA, mm²) were recorded.

Results

Compared to CG, a larger percentage of supinated feet was examined in relatively severe legs (5, 23.81%), relatively moderate legs (4, 19.05%), and merged results (9, 21.43%) of PG (P < 0.05), and the percentage of severe asymmetry (38.1%) was higher in the PG (P < 0.05). Moreover, these relationships between the absolute value of asymmetry score and SL or SA were significant in CG and PG, the P values below 0.01.

Conclusions

Foot posture asymmetry is significantly associated with static stability both in KOA patients and healthy adults, and more severe asymmetry in foot posture was observed in KOA patients, so it is critical to evaluate foot posture asymmetry for treatment and rehabilitation for patients with KOA.

The Role of the Podiatrist in Assessing and Reducing Fall Risk: An Updated Review

Falls present a tremendous challenge to health care systems. This article reviews the literature from the previous 5 years (2014-2019) in terms of methods to assess fall risk and potential steps that can be taken to reduce fall risk for patients visiting podiatric clinics. With regard to assessing fall risk, we discuss the role of a thorough medical history and podiatric assessments of foot problems and deformities that can be performed in the clinic. With regard to fall prevention we consider the role of shoe modification, exercise, pain relief, surgical interventions, and referrals.