Temporal adaptations in generic and population-specific quality of life and falls efficacy in men with recent lower-limb amputations

This study examined the longitudinal changes in generic health-related quality of life (QOL), prosthesis-related QOL, falls efficacy, and walking speed in men with lower-limb amputations up to 6 months following discharge from rehabilitation. Seven male unilateral transtibial amputees completed the Medical Outcomes Study 36-Item Short Form Health Survey, the Prosthesis Evaluation Questionnaire, and the Modified Falls Efficacy Scale at 1, 3, and 6 months postdischarge from rehabilitation. Walking speed was also recorded to objectively assess participants’ mobility. Health-related QOL measures displayed increases, resulting in large effect sizes though not reaching statistical significance. Prosthesis-related QOL measures indicated that scales relating to the participants’ prostheses improved and the support of significant others was the most positively scored variable. Walking speed increased by 0.12 m/ s, although it was not significantly related to indices of QOL or falls efficacy. Falls efficacy did not improve significantly during the study period, although it was strongly related to QOL ( p < 0.05). These results provide a novel insight into how QOL and falls efficacy develop in people with lower-limb amputations, alongside changes in mobility, after discharge from rehabilitation. Further improvements in physical health following discharge may be required to elicit subsequent increases in overall QOL and concurrent improvements in falls efficacy

Exercise interventions for weight management during pregnancy and up to 1 year postpartum among normal weight, overweight and obese women: a systematic review and meta-analysis

Background: The prevalence of excessive gestation weight gain, extended postpartum weight retention and pre-gravid obese women is increasing and is associated with numerous adverse health outcomes. Objective To review the evidence from studies employing exercise-only interventions for weight management among pregnant and postpartum women. Search strategy Ten databases were searched for randomised controlled trials (RCTs) conducted during pregnancy or within the 12 month following childbirth and published between 1990 and 2013. Selection criteria: There were no restrictions to the type, frequency, duration or intensity of exercise intervention. Interventions not specifically designed to target weight were excluded. The outcomes were a change in body weight (kg) or body mass index (BMI; kg·m2). Data collection and analysis: All data were continuous and were reported as weighted mean differences (WMD), with 95% confidence intervals (CI). Data were analysed with a fixed-effect model and heterogeneity was determined using the I2 statistic. Results: Five studies were included in this review. Exercise significantly reduced gestational weight gain (WMD=-2.22kg, CI=-3.14/-1.3, p=<0.00001) and had no significant effect on postpartum weight loss (WMD=-1.74kg, CI=-3.59/0.10, p=0.06) or BMI during pregnancy (WMD=-2.8kg·m2, CI=-5.60/0.00, p=0.05) or postpartum (WMD=-0.54kg·m2, CI=-1.17/0.08, p=0.09). Conclusions: There is currently limited evidence to suggest that exercise can be used to limit maternal gestational weight gain

Optimisation of a machine learning algorithm in human locomotion using principal component and discriminant function analyses

Assessment methods in human locomotion often involve the description of normalised graphical profiles and/or the extraction of discrete variables. Whilst useful, these approaches may not represent the full complexity of gait data. Multivariate statistical methods, such as Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA), have been adopted since they have the potential to overcome these data handling issues. The aim of the current study was to develop and optimise a specific machine learning algorithm for processing human locomotion data. Twenty participants ran at a self-selected speed across a 15m runway in barefoot and shod conditions. Ground reaction forces (BW) and kinematics were measured at 1000 Hz and 100 Hz, respectively from which joint angles (°), joint moments (N.m.kg-1) and joint powers (W.kg-1) for the hip, knee and ankle joints were calculated in all three anatomical planes. Using PCA and DFA, power spectra of the kinematic and kinetic variables were used as a training database for the development of a machine learning algorithm. All possible combinations of 10 out of 20 participants were explored to find the iteration of individuals that would optimise the machine learning algorithm. The results showed that the algorithm was able to successfully predict whether a participant ran shod or barefoot in 93.5% of cases. To the authors’ knowledge, this is the first study to optimise the development of a machine learning algorithm

Which prosthetic foot to prescribe?

Introduction: Clinicians typically use findings from cohort studies to objectively inform judgements regarding the potential (dis)advantages of prescribing a new prosthetic device. However, before finalising prescription a clinician will typically ask a patient to 'try out' a change of prosthetic device while the patient is at the clinic. Observed differences in gait when using the new device should be the result of the device’s mechanical function, but could also conceivably be due to patient related factors which can change from day-to-day and can thus make device comparisons unreliable. To determine whether a device’s mechanical function consistently has a more meaningful impact on gait than patient-related factors, the present study undertook quantitative gait analyses of a trans-tibial amputee walking using two different foot-ankle devices on two occasions over a year apart. If the observed differences present between devices, established using quantitative gait analysis, were in the same direction and of similar magnitude on each of the two occasions, this would indicate that device-related factors were more important than patient-related factors. Methods: One adult male with a unilateral trans-tibial amputation completed repeated walking trials using two different prosthetic foot devices on two separate occasions, 14 months apart. Walking speed and sagittal plane joint kinematics and kinetics for both limbs were assessed on each occasion. Clinically meaningful differences in these biomechanical outcome variables were defined as those with an effect size difference (d) between prosthetic conditions of at least 0.4 (i.e. 'medium' effect size). Results: Eight variables namely, walking speed, prosthetic 'ankle' peak plantar- and dorsi-flexion and peak positive power, and residual knee loading response flexion, peak stance-phase extension and flexion moments and peak negative power, displayed clinically meaningful differences (d > 0.4) between foot devices during the first session. All eight of these showed similar effect size differences during the second session despite the participant being heavier and older. Conclusions: Findings suggest that a prosthetic device's mechanical function consistently has a more meaningful impact on gait than patient-related factors. These findings support the current clinical practice of making decisions regarding prosthetic prescription for an individual, based on a single session evaluation of their gait using two different devices. However, to confirm this conclusion, a case series using the same approach as the present study could be undertaken

Does an inverted pendulum model accurately represent the gait of individuals with unilateral transfemoral amputation while walking over level ground?

Study Design: Controlled trial Background: An inverted pendulum model represents the mechanical function of able-bodied walking accurately, with centre of mass height and forward velocity data plotting as sinusoidal curves, 180 degrees out of phase. Objectives: The current study investigated whether the inverted pendulum model represented level gait in individuals with a unilateral transfemoral amputation. Methods: Kinematic and kinetic data from ten individuals with unilateral transfemoral amputation and fifteen able-bodied participants were recorded during level walking. Results: During level walking, the inverted pendulum model described able-bodied gait well throughout the gait cycle, with median relative time shifts between centre of mass height and velocity maxima and minima of between 1.2%-1.8% of gait cycle. In the group with unilateral transfemoral amputation, the relative time shift was significantly increased during the prosthetic limb initial double-limb support phase by 6.3%. Conclusion: The gait of individuals with unilateral transfemoral amputation shows deviation from a synchronous inverted pendulum model during prosthetic limb stance. The reported divergence may help explain such individuals’ increased metabolic cost of gait. Temporal divergence of inverted pendulum behaviour could potentially be utilised as a tool to assess the efficacy of prosthetic device prescription

Do predictive relationships exist between postural control and falls efficacy in unilateral transtibial prosthesis users?

Objective: To assess whether variables from a postural control test relate to and predict falls efficacy in prosthesis users. Design: Twelve-month within and between subjects repeated measures design. Participants performed the Limits of Stability (LOS) test protocol at study baseline and at 6-month follow-up. Participants also completed the Falls Efficacy Scale-International (FES-I) questionnaire, reflecting the fear of falling, and reported the number of falls monthly between study baseline and 6-month follow-up, and additionally at 9- and 12-month follow-ups. Setting: University biomechanics laboratories. Participants: A group of active unilateral transtibial prosthesis users of primarily traumatic etiology (PROS) (n=12) with at least one year of prosthetic experience and age and gender matched control participants (CON) (n=12). Interventions: Not applicable. Main Outcome Measure(s): Postural control variables derived from centre of pressure data obtained during the LOS test, which was performed on and reported by the Neurocom Pro Balance Master, namely; reaction time (RT), movement velocity (MVL), endpoint (EPE) and maximum (MXE) excursion and directional control (DCL). Number of falls and total FES-I scores. Results: During the study period, the PROS group had higher FES-I scores (U = 33.5, p =0.02), but experienced a similar number of falls, compared to the CON group. Increased FES-I score were associated with decreased EPE (R=-0.73, p=0.02), MXE (R=-0.83, p<0.01) and MVL (R=-0.7, p=0.03) in the PROS group, and DCL (R=-0.82, p<0.01) in the CON group, all in the backwards direction. Conclusions: Study baseline measures of postural control, in the backwards direction only, are related to and potentially predictive of subsequent 6-month FES-I scores in relatively mobile and experienced prosthesis users

Joint moments during downhill and uphill walking of a person with transfemoral amputation with a hydraulic articulating and a rigid prosthetic ankle—a case study

Introduction: Functional characteristics of prosthetic ankle design may facilitate sloped walking for transfemoral amputees. The aim of the current case-study was to analyse the effects of a rigid vs. a hydraulically articulating ankle component on the biological joint moments of a transfemoral amputee during downhill, uphill and level walking. Methods: The gait of one unilateral transfemoral amputee, using the same prosthetic foot with rigid and hydraulic ankle components, was analysed and compared to a control group of 18 able-bodied participants. Kinematic and kinetic data were recorded at self-selected walking speed on a sloped ramp with inclinations of -12°, -4° (downhill), 0° (level), +4° and +12° (uphill). Results: The slope influenced lower limb joint moments similarly in both able-bodied and transfemoral participants. The effect of altering ankle movement through exchanging prosthetic ankle componentry was most acutely seen at the hip joint of the residual limb. The use of a hydraulic ankle joint component resulted in decreased mean hip joint extension and flexion moments of up to 92% and 48% respectively in the residual limb when compared to using the rigid ankle joint component, respectively. Conclusion: During sloped walking, the use of a hydraulically articulating vs. rigid ankle joint component reduced the joint moments observed at the hip joint of the residual limb in a unilateral transfemoral amputee. This indicates a benefit for transfemoral amputees as the increased ankle function reduces the moment producing requirements of the hip joint which may result in decreased energy consumption and subsequently, a more efficient gait

The calculation, thresholds and reporting of inter-limb strength asymmetry: a systematic review

The prevalence of inter-limb strength differences is well documented in the literature however, there are inconsistencies related to measurement and reporting, and the normative values and effects associated with inter-limb asymmetry. Therefore, the aims of this systematic review were to: 1) assess the appropriateness of existing indices for the calculation of asymmetry, 2) interrogate the evidence basis for literature reported thresholds used to define asymmetry and 3) summarise normative levels of inter-limb strength asymmetry and their effects on injury and performance. To conduct this systematic review, scientific databases (PubMed, Scopus, SPORTDiscus and Web of Science) were searched and a total of 3,594 articles were retrieved and assessed for eligibility and article quality. The robustness of each identified asymmetry index was assessed, and the evidence-basis of the identified asymmetry thresholds was appraised retrospectively using the references provided. Fifty-three articles were included in this review. Only four of the twelve identified indices were unaffected by the limitations associated with selecting a reference limb. Eighteen articles applied a threshold to original research to identify “abnormal” asymmetry, fifteen of which utilised a threshold between 10-15%, yet this threshold was not always supported by appropriate evidence. Asymmetry scores ranged between and within populations from approximate symmetry to asymmetries larger than 15%. When reporting the effects of strength asymmetries, increased injury risk and detriments to performance were often associated with larger asymmetry, however the evidence was inconsistent. Limitations of asymmetry indices should be recognised, particularly those that require selection of a reference limb. Failure to reference the origin of the evidence for an asymmetry threshold reinforces doubt over the use of arbitrary thresholds, such as 10-15%. Therefore, an individual approach to defining asymmetry may be necessary to refine robust calculation methods and to establish appropriate thresholds across various samples and methodologies that enable appropriate conclusions to be drawn

Individuals with unilateral transtibial amputation exhibit reduced accuracy and precision during a targeted stepping task

Accurate foot placement is important for dynamic balance during activities of daily living. Disruption of sensory information and prosthetic componentry characteristics may result in increased locomotor task difficulty for individuals with lower limb amputation. This study investigated the accuracy and precision of prosthetic and intact foot placement during a targeted stepping task in individuals with unilateral transtibial amputation (IUTAs; N=8, 47±13 yrs), compared to the preferred foot of control participant’s (N=8, 33±15 yrs). Participants walked along a 10-metre walkway, placing their foot into a rectangular floor-based target with dimensions normalised to a percentage of participant’s foot length and width; ‘standard’ = 150%x150%, ‘wide’ = 150%x200%, ‘long’ = 200%x150%. Foot placement accuracy (relative distance between foot and target centre), precision (between-trial variability), and foot-reach kinematics were determined for each limb and target, using three-dimensional motion capture. A significant foot-by-target interaction revealed less mediolateral foot placement accuracy for IUTAs in the wide target, which was significantly less accurate for the intact (28±12mm) compared to prosthetic foot (16±14mm). Intact peak foot velocity (4.6±0.8m.s-1) was greater than the prosthetic foot (4.5±0.8m.s-1) for all targets. Controls were more accurate and precise than IUTAs, regardless of target size. Less accurate and precise intact foot placement in IUTAs, coupled with a faster moving intact limb, is likely due to several factors including reduced proprioceptive feedback and active control during prosthetic limb single stance. This could affect activities of daily living where foot placement is critical, such as negotiating cluttered travel paths or obstacles whilst maintaining balance