Self-reported functional mobility, balance confidence, and prosthetic use predict short-term average daily step counts as determined from research-grade accelerometers.

Identifying the role of passive-dynamic ankle-foot orthosis stiffness during gait provides biomechanical rationale for how to customize passive-dynamic ankle-foot orthoses for patients. Furthermore, these findings can be used in the future as the basis for developing objective prescription models to help drive the customization of passive-dynamic ankle-foot orthosis characteristics.

Both monitors accurately counted steps during forward linear walking. StepWatch appears to be more accurate than FitBit during complex walking but a larger sample size may confirm these findings. FitBit consistently counted fewer steps than StepWatch during free-living walking. Clinical relevance The StepWatch and FitBit are acceptable tools for assessing forward, linear walking for individuals with transtibial amputation. Given the results' consistenty in the free-living enviorment, both tools may ultimiately be able to be used to count steps in the real world, but more research is needed to confirm these findings.

Introduction The ability to walk with different cadences (cadence variability) is considered an important factor for determining the functional ability of individuals with lower-limb amputation and making prosthetic recommendations. However, a method to quantify cadence variability of these individuals has never been presented before, so there are no standardized methodologies or values to guide prosthesis prescription. The purpose of this study was to develop and demonstrate feasibility of a method to quantify real-world cadence variability. Materials and Methods The method utilizes step-count data collected by an accelerometer-based activity monitor. Cadence at each minute is calculated. Then, the spread of the cadence data distribution during a 7-day observation period is measured to quantify cadence variability. To demonstrate feasibility, this method was applied to a set of step-count data for individuals with unilateral lower-limb amputation classified by their health care provider as a K2 or K3 ambulator. Results Results showed that this method was able to differentiate the cadence characteristics of individuals classified as K2 versus K3. On average, individuals classified as K2 walked with significantly less cadence variability than those classified as K3. Conclusions This study provides a novel method for objectively determining cadence variability and provides a foundation for ultimately developing normative cadence characteristic values for K2 and K3 levels.

By determining that gait speed, not age, is related to NAS in older adults, this study represents the initial step towards objectively prescribing PD-AFO bending stiffness to achieve a targeted gait speed for older adults with plantar flexor weakness.

Background Previous research shows kinematic and kinetic coupling between the metatarsophalangeal (MTP) and midtarsal joints during gait. Studying the effects of MTP position as well as foot structure on this coupling may help determine to what extent foot coupling during dynamic and active movement is due to the windlass mechanism. This study’s purpose was to investigate the kinematic and kinetic foot coupling during controlled passive, active, and dynamic movements. Methods After arch height and flexibility were measured, participants performed four conditions: Seated Passive MTP Extension, Seated Active MTP Extension, Standing Passive MTP Extension, and Standing Active MTP Extension. Next, participants performed three heel raise conditions that manipulated the starting position of the MTP joint: Neutral, Toe Extension, and Toe Flexion. A multisegment foot model was created in Visual 3D and used to calculate ankle, midtarsal, and MTP joint kinematics and kinetics. Results Kinematic coupling (ratio of midtarsal to MTP angular displacement) was approximately six times greater in Neutral heel raises compared to Seated Passive MTP Extension, suggesting that the windlass only plays a small kinematic role in dynamic tasks. As the starting position of the MTP joint became increasingly extended during heel raises, the amount of negative work at the MTP joint and positive work at the midtarsal joint increased proportionally, while distal-to-hindfoot work remained unchanged. Correlations suggest that there is not a strong relationship between static arch height/flexibility and kinematic foot coupling. Conclusions Our results show that there is kinematic and kinetic coupling within the distal foot, but this coupling is attributed only in small measure to the windlass mechanism. Additional sources of coupling include foot muscles and elastic energy storage and return within ligaments and tendons. Furthermore, our results suggest that the plantar aponeurosis does not function as a rigid cable but likely has extensibility that affects the effectiveness of the windlass mechanism. Arch structure did not affect foot coupling, suggesting that static arch height or arch flexibility alone may not be adequate predictors of dynamic foot function.

Background: In the United States, Medicare Functional Classification Level (K-level) guidelines require demonstration of cadence variability to justify higher-level prosthetic componentry prescription; however, clinical assessment of cadence variability is subjective. Currently, no clinical outcome measures are associated with cadence variability during community ambulation. Objectives: Evaluate whether physical performance, i.e. 10-meter Walk Test (10mWT)-based walking speeds, L-Test, and Figure-of-8 Walk Test scores, is associated with community-based cadence variability among individuals with a transtibial amputation. Study design: Cross-sectional. Methods: Forty-nine participants, aged 18–85 years, with a unilateral transtibial amputation were included. Linear regression models were conducted to determine whether physical performance was associated with cadence variability (a unitless calculation from FitBit® OneTM minute-by-minute step counts), while controlling for sex, age, and time since amputation ( p ⩽ .013). Results: Beyond covariates, self-selected gait speed explained the greatest amount of variance in cadence variability (19.2%, p < .001). Other outcome measures explained smaller, but significant, amounts of the variance (11.1–17.1%, p = .001–.008). For each 0.1 m/s-increase in self-selected and fast gait speeds, or each 1-s decrease in L-Test and F8WT time, community-based cadence variability increased by 1.76, 1.07, 0.39, and 0.79, respectively ( p < .013). Conclusions: In clinical settings, faster self-selected gait speed best predicted increased cadence variability during community ambulation. Clinical relevance The 10-meter Walk Test may be prioritized during prosthetic evaluations to provide objective self-selected walking speed data, which informs the assessment of cadence variability potential outside of clinical settings.

Bending stiffness of passive-dynamic ankle-foot orthoses (PD-AFOs) is a functional characteristic thought to restore lost ankle function due to weakened plantar flexors. However, lower extremity impairment profiles of patients are seldom limited to plantar flexion weakness, and PD-AFO characteristics often influence gait in other ways. Combined, all PD-AFO characteristics and patient impairments likely mask the main effect of PD-AFO bending stiffness and complicate the PD-AFO bending stiffness prescription process. In this study, we propose a biomechanical probing paradigm, where customized PD-AFOs with a range of precise stiffness values are worn by healthy subjects, to experimentally test a PD-AFO strength substitution hypothesis while simultaneously documenting gait adaptations to PD-AFO use. Two healthy subjects walked at a scaled velocity while wearing a series of three PD-AFOs that ranged in bending stiffness levels. Supporting the strength substitution hypothesis, peak ankle plantar flexion moments remained unchanged across PD-AFO stiffness conditions. Further biomechanical analyses documented a complex series of ankle related kinematic and kinetic adaptive movement strategies due to PD-AFO use. This study demonstrated the utility of the biomechanical probing paradigm to help understand the contribution of PD-AFO stiffness to ankle strength and its secondary effects on ankle biomechanics.