Altered mechanics and increased loading on intact limbs of individuals with a unilateral transtibial amputation in comparison with non-amputees during a start-stop task.

Individuals with a unilateral transtibial amputation (ITTA) often experience greater loading on the intact limb during running and stepping tasks compared to individuals without amputation. This study aimed to investigate the mechanics of load absorption in the intact limb of ITTA and determine if increased ground reaction forces (GRF) persist during a start-stop task which (i) controlled touch-down velocity and (ii) removed the requirement for on-going locomotion. Data were collected using a twelve-camera motion capture system with two Kistler force platforms. Variables were extracted during the final loading phase of a 2-step start-stop task. The intact limb of ITTA and the dominant limb of able-bodied controls were compared using independent t-tests and effect size analysis. ITTA showed lower knee flexion angles at touchdown (p = 0.007, g = -1.43), and peak vertical GRF (p = 0.01, g = -1.33) compared to control subjects. ITTA also exhibited less hip (p = 0.14, g = 0.76) and ankle (p = 0.002, g = 1.82) absorptive power at touchdown and at peak vertical GRF (hip: p = 0.01, g = 1.23; ankle: p = 0.05, g = 0.97). ITTA exhibited greater peak vertical GRF (p = 0.01, g = 1.30) and braking GRF (p = 0.05, g = -0.96) on the intact limb compared to the controls. Our results indicate altered joint mechanics through the intact limb of ITTA are independent of the touchdown conditions or the need for ongoing locomotion. These altered joint mechanics increased loading experienced by the intact limb. Further work should be conducted examining a variety of other dynamic movements to fully understand the involved mechanics, so that intervention studies can be developed to reduce the load experienced by ITTA.

Dietary intakes and prevalence of overweight/obesity in male non-dysvascular lower limb amputees.

BACKGROUND: Lower limb amputees are at higher risk of cardiovascular disease compared to non-amputees. Dietary intake, a major determinant of cardiovascular disease risk, has not previously been studied in this group. OBJECTIVE: The aim of this study was to investigate dietary intakes and prevalence of overweight/obesity in adult lower limb amputees. STUDY DESIGN: A cross-sectional survey was used to investigate the dietary intake and prevalence of overweight/obesity in adults with lower limb amputations living in the United Kingdom. METHOD: Dietary intakes of male adult lower limb amputees ( n = 46, non-dysvascular) were assessed using food frequency questionnaires and results were compared to dietary reference values in the United Kingdom. Prevalence of overweight/obesity was assessed through body mass index and waist-to-hip ratio and compared to the general population according to the Health Survey for England 2011. RESULTS: Dietary intake risk factors for cardiovascular disease such as sugars (22.01%), total fat (34.87%), saturated fat (12.72%) and sodium (2660.10 mg/day) were significantly higher ( p < 0.001, p < 0.001, p = 0.043, p < 0.001; p < 0.001; respectively) than the dietary reference values. A high prevalence (82.8%) of overweight/obesity was found with a significantly higher body mass index and waist-to-hip ratio ( p = 0.027; p = 0.001; respectively) compared to the Health Survey for England 2011. CONCLUSION: High intakes of sugars, dietary fats, sugars and salts, combined with high prevalence of overweight/obesity observed in lower limb amputees are concerning. These findings suggest that greater emphasis on dietary intakes should be considered for rehabilitation programmes. CLINICAL RELEVANCE: Findings highlight poor dietary habits in lower limb amputees with respect to fat, sugar and salt intake, also high levels of overweight/obesity. Considering greater emphasis on dietary intake and including lifestyle changing interventions in rehabilitation programmes for lower limb amputees may lower the risk of obesity and CVD.

Running at submaximal speeds, the role of the intact and prosthetic limbs for trans-tibial amputees.

BACKGROUND: Dynamic Elastic Response prostheses are designed to absorb and return strain energy in running. Past research has focused on running prostheses with a single toe spring designed for high speeds. RESEARCH QUESTION: To determine how runners with amputation modulate the ground reaction force of each limb to run at different speeds using a general-purpose dynamic prosthesis which has a heel spring. METHODS: Overground running data were collected in 16 recreational runners (8 transtibial amputee using their own BladeXT prosthesis and 8 controls) using Vicon Nexus V.2.5 with Kistler force plates. Participants ran at self-selected running pace, 70% and 130% of that pace. Vertical, braking and propulsion peak ground reaction forces and impulses and vertical loading and decay rates were analysed between limbs at each speed (ANOVA) and their association with speed assessed (simple linear regression). RESULTS: The vertical, braking forces and impulses and propulsive force were significantly less (p < 0.05) on the prosthetic limb than controls at the faster speed, but there was no difference in the propulsive impulse. The intact limb did not evidence increased vertical force at any speed, but experienced increased braking (p < 0.05) compared to both prosthetic limb and controls at the slow speed. For all limbs, braking and propulsive peak forces, decay rate, step length and step frequency were strongly (r > 0.6) and significantly (p < 0.05) associated with speed. On the prosthetic limb vertical impulse was strongly and significantly negatively associated with speed and control's braking impulse was associated with speed. SIGNIFICANCE: A leg-specific response was found at different speeds. On the prosthetic limb the technique was to brake less not propel more at higher speeds with reduced vertical drive. Running at self-selected speed could be used for fitness without inducing detrimental ground reaction forces on the intact limb or evoking asymmetry in step length and frequency.

Dynamic elastic response prostheses alter approach angles and ground reaction forces but not leg stiffness during a start-stop task.

In a dynamic elastic response prosthesis (DERP), spring-like properties aim to replace the loss of musculature and soft tissues and optimise dynamic movement biomechanics, yet higher intact limb (IL) loading exists. It is unknown how amputees wearing a DERP will perform in start-stop movements and how altering the prosthetic stiffness will influence the performance and loading. This study assessed movement dynamics through comparisons in spatiotemporal, kinematic and kinetic variables and leg stiffness of intact, prosthetic and control limbs. The effect of prosthetic stiffness on movement dynamics was also determined. Eleven male unilateral transtibial amputees performed a start-stop task with one DERP set at two different stiffness - Prescribed and Stiffer. Eleven control participants performed the movement with the dominant limb. Kinematic and kinetic data were collected by a twelve-camera motion capture system synchronised with a Kistler force platform. Selected variables were compared between intact, prosthetic and control limbs, and against prosthetic stiffness using ANOVA and effect size. Pearson's Correlation was used to analyse relationship between leg stiffness and prosthetic deflection. Amputees showed a more horizontal approach to the bound during the start-stop movement, with lower horizontal velocities and a longer stance time on the IL compared to controls. In both stiffness conditions, the IL showed selected higher anteroposterior and vertical forces and impulses when compared to the controls. Leg stiffness was not significantly different between limbs as a result of the interplay between angle swept and magnitude of force, even with the change in prosthetic stiffness. A main effect for prosthetic stiffness was found only in higher impact forces of the prosthetic limb and more horizontal touchdown angles of the IL when using the prescribed DERP. In conclusion, amputees achieve the movement with a horizontal approach when compared to controls which may reflect difficulty of movement initiation with a DERP and a difficulty in performing the movement dynamically. The forces and impulses of the IL were high compared to control limbs. The consistent leg stiffness implies compensation strategies through other joints.

A High Omega-3 Fatty Acid Multinutrient Supplement Benefits Cognition and Mobility in Older Women: A Randomized, Double-blind, Placebo-controlled Pilot Study.

BACKGROUND: Mobility is a key determinant of frailty in older persons, and a variety of dietary factors, such as the omega-3 fatty acid docosahexaenoic acid (DHA), are positively associated with decreased frailty and improved mobility and cognition in older persons. METHODS: The effects of a multinutrient supplement on mobility and cognition were assessed in postmenopausal women (60-84 years). Participants received either Efalex Active 50+ (1g DHA, 160 mg eicosapentaenoic acid, 240 mg Ginkgo biloba, 60 mg phosphatidylserine, 20mg d-α tocopherol, 1mg folic acid, and 20 µg vitamin B12 per day; N = 15) or placebo (N = 12) for 6 months. Mobility was assessed by VICON 9 motion capture camera system synchronized with Kistler force plates, cognitive performance by computerized cognitive function tests, and blood fatty acid levels by pin-prick analysis. RESULTS: Significant effects of treatment were seen in two of the four cognitive tests, with shorter mean latencies in a motor screening task (p < .05) and more words remembered (p < .03), and one of the three primary mobility measures with improved habitual walking speed (p < .05). Compared with the placebo group, supplementation also resulted in significantly higher blood DHA levels (p < .02). CONCLUSIONS: In this pilot study, multinutrient supplementation improved cognition and mobility in able older females at clinically relevant levels, suggesting a potential role in reducing the decline to frailty.

Can a Single-Leg Squat Provide Insight Into Movement Control and Loading During Dynamic Sporting Actions in Patients With Athletic Groin Pain?

CONTEXT: Chronic athletic groin pain (AGP) is common in field sports and has been associated with abnormal movement control and loading of the hip and pelvis during play. A single-leg squat (SLS) is commonly used by clinicians to assess movement control, but whether it can provide insight into control during more dynamic sporting movements in AGP patients is unclear. OBJECTIVE: To determine the relationships between biomechanical measures in an SLS and the same measures in a single-leg drop landing, single-leg hurdle hop, and a cutting maneuver in AGP patients. DESIGN: Cross-sectional study. SETTING: Biomechanics laboratory. PATIENTS: 40 recreational field-sports players diagnosed with AGP. INTERVENTION: A biomechanical analysis of each individual's SLS, drop landing, hurdle hop, and cut was undertaken. MAIN OUTCOME MEASURES: Hip, knee, and pelvis angular displacement and hip and knee peak moments. Pearson product-moment correlations were used to examine relationships between SLS measures and equivalent measures in the other movements. RESULTS: There were no significant correlations between any hip or pelvis measure in the SLS with the same measures in the drop landing, hurdle hop, or cut (r = .03-.43, P > .05). Knee frontal- and transverse-plane angular displacement were related in the SLS and drop landing only, while knee moments were related in the SLS, drop-landing, and hurdle hop (r = .50-.67, P < .05). CONCLUSION: For AGP patients, an SLS did not provide meaningful insight into hip and pelvis control or loading during sporting movements that are associated with injury development. The usefulness of an SLS test in the assessment of movement control and loading in AGP patients is thus limited. The SLS provided moderate insight into knee control while landing and therefore may be of use in the examination of knee-injury risk.

Kinematic differences exist between transtibial amputee fallers and non-fallers during downwards step transitioning.

BACKGROUND: Stair negotiation is biomechanically more challenging than level gait. There are few biomechanical assessments of transtibial amputees descending stairs and none specifically related to falls. Stair descent may elicit more differences than level gait in amputees with and without a previous falls history. OBJECTIVES: The aim of this study was to compare the gait kinematics of fallers and non-fallers during downwards step transitioning in transtibial amputees. STUDY DESIGN: Cross-sectional study. METHODS: Six fallers and five non-fallers completed step transition trials on a three-step staircase at their self-selected pace. RESULTS: Nine participants exhibited a clear preference to lead with the affected limb, while two had no preference. Four participants self-selected a step-to rather than a reciprocal stair descent strategy. The fallers who used a reciprocal strategy walked 44% more quickly than the non-fallers. To compensate for the lack of active plantar flexion of the prosthetic foot, exaggerated range of motion occurred proximally at the pelvis during swing. The step-to group was more reliant on the handrails than the reciprocal group and walked more slowly. CONCLUSION: As anticipated, the fallers walked faster than the non-fallers despite employing the more difficult 'roll-over' technique. Handrail use could help to improve dynamic control during downwards step transitions. CLINICAL RELEVANCE: Transtibial amputees are advised to descend steps using external support, such as handrails, for enhanced dynamic control. Hip abductor and knee extensor eccentric strength should be improved through targeted exercise. Prosthetic socket fit should be checked to allow adequate knee range of motion on the affected side.

Biomechanical factors associated with time to complete a change of direction cutting maneuver.

Cutting ability is an important aspect of many team sports, however, the biomechanical determinants of cutting performance are not well understood. This study aimed to address this issue by identifying the kinetic and kinematic factors correlated with the time to complete a cutting maneuver. In addition, an analysis of the test-retest reliability of all biomechanical measures was performed. Fifteen (n = 15) elite multidirectional sports players (Gaelic hurling) were recruited, and a 3-dimensional motion capture analysis of a 75° cut was undertaken. The factors associated with cutting time were determined using bivariate Pearson's correlations. Intraclass correlation coefficients (ICCs) were used to examine the test-retest reliability of biomechanical measures. Five biomechanical factors were associated with cutting time (2.28 ± 0.11 seconds): peak ankle power (r = 0.77), peak ankle plantar flexor moment (r = 0.65), range of pelvis lateral tilt (r = -0.54), maximum thorax lateral rotation angle (r = 0.51), and total ground contact time (r = -0.48). Intraclass correlation coefficient scores for these 5 factors, and indeed for the majority of the other biomechanical measures, ranged from good to excellent (ICC >0.60). Explosive force production about the ankle, pelvic control during single-limb support, and torso rotation toward the desired direction of travel were all key factors associated with cutting time. These findings should assist in the development of more effective training programs aimed at improving similar cutting performances. In addition, test-retest reliability scores were generally strong, therefore, motion capture techniques seem well placed to further investigate the determinants of cutting ability.

Asymmetrical loading demands associated with vertical jump landings in people with unilateral transtibial amputation.

Loading symmetry during vertical jump landings between a person with amputation's intact and prosthetic limbs was assessed to determine the role of each limb in controlling the downward momentum of the center of mass during landing. Six participants with unilateral transtibial amputation (TTA) and ten nondisabled participants completed 10 maximal vertical jumps, of which the highest jump was analyzed. Contralateral symmetry was assessed through the Symmetry Index (SI), while symmetry at the group level was assessed through a Mann-Whitney U test. Participants with TTA performed quasi-unilateral landings onto the intact limbs, resulting from either the incapability of the prosthetic ankle to plantar flex or increased residual-limb knee and hip flexion. In the loading phase, the participants with TTA displayed reduced prosthetic-side peak vertical forces (p = 0.04) along with reduced prosthetic-side ankle range of motion (p < 0.001), extensor moments (p = 0.03), and negative work generated (p = 0.00). Individual asymmetries were evident in the peak vertical force magnitudes (SI = 51%-140%), duration from touchdown to peak vertical force (SI = 52%-157%), ankle joint angles at touchdown (SI = 100%-538%), ranges of motion (SI = 147%-200%), knee (SI = 66%-179%) and hip (SI = 87%-132%) extensor moments, and work done at the ankle (SI = 155%-199%) and hip (SI = 83%-204%). High peak forces (25.25 +/- 4.89 N·kg(-1) intact limb and 14.61 +/- 8.28 N·kg(-1) prosthetic limb) from significantly lower (p < 0.001) landing heights than the nondisabled participants indicate a potential injury risk associated with landing for people with TTA.

Mechanisms to absorb load in amputee running.

BACKGROUND: We aimed to determine if a shock absorbing pylon (SAP) influenced the ground reaction force characteristics and the shock absorbing mechanisms compared to a rigid pylon (Rigid) during the loading phase in running. OBJECTIVES: To determine if the SAP influences the mechanisms of loading compared to the Rigid condition. STUDY DESIGN: A convenience sample of transtibial amputees participated in a laboratory-based study. The prosthetic set-up was randomly altered fd\sdsd. METHODS: Five recreationally active male transtibial amputees age: 18-50 years; mean mass: 86.7 ± 17.5 kg; height: 1.77 ± 0.07 m) volunteered from a population-based sample. They completed a within-participant-designed study assessing a SAP and a Rigid condition during running. Kinematic and kinetic data were collected during two sessions following a one-week customization period. RESULTS: Loading rate, peak vertical and horizontal ground reaction forces and the time to each measure along with knee and hip angular displacement, absorbing powers and work done between the SAP and Rigid conditions were not systematically affected by the prosthetic condition. CONCLUSIONS: The effect of the SAP was minimal and inconsistent in the loading phase, with only some amputees presenting higher and others with lower values for the tested variables.

Kinetic and kinematic compensations in amputee vertical jumping.

A unilateral transtibial amputation causes a disruption to the musculoskeletal system, which results in asymmetrical biomechanics. The current study aimed to assess the movement asymmetry and compensations that occur as a consequence of an amputation when performing a countermovement vertical jump. Six unilateral transtibial amputees and 10 able-bodied (AB) participants completed 10 maximal vertical jumps, and the highest jump was analyzed further. Three-dimensional lower limb kinematics and normalized (body mass) kinetic variables were quantified for the intact and prosthetic sides. Symmetry was assessed through the symmetry index (SI) for each individual and statistically using the Mann-Whitney U test between the intact and prosthetic sides for the amputee group. A descriptive analysis between the amputee and AB participants was conducted to explore the mechanisms of amputee jumping. The amputee jump height ranged from 0.09 to 0.24 m. In the countermovement, all ankle variables were asymmetrical (SI > 10%) and statistically different (p < .05) for the amputees. At the knee and hip, there was no statistical difference between the intact and prosthetic sides range of motion, although there was evidence of individual asymmetry. The knees remained more extended compared with the AB participants to prevent collapse. In propulsion, the prosthesis did not contribute to the work done and the ankle variables were asymmetrical (p < .05). The knee and hip variables were not statistically different between the intact and prosthetic sides, although there was evidence of functional asymmetry and the contribution tended to be greater on the intact compared with the prosthetic side. The lack of kinetic involvement of the prosthetic ankle and both knees due to the limitation of the prosthesis and the altered musculoskeletal mechanics of the joints were the reason for the reduced height jumped.

The temporal-spatial and ground reaction impulses of turning gait: is turning symmetrical?

This study had two aims. Firstly, to characterise the temporal-spatial and ground reaction impulse adjustments, compared to straight gait, required to complete step turns to the left and to the right and secondly, to assess if the turns were asymmetrical. Seven participants were instructed to perform 90 degrees step turns to the left and right. The actual angle turned was less for both turns (right 80.2+/-5.5 degrees , left 82.8+/-5.3 degrees ). Data were collected using a 7 camera VICON infra-red motion analysis system (120 Hz) and a Kistler force plate (600 Hz). Adjustments were made in the approach, turn and depart strides compared to straight gait. The mean velocity was significantly lower and the stride was significantly shorter in the approach stride before the turn (p<0.0125) compared to straight gait, indicating a possible feed-forward mechanism prior to turning. Velocity was significantly lower and the stride length significantly shorter during the depart stride (p<0.0125) compared to straight gait. Participants did not return to a normal pattern within one stride. For the turn step, the velocity, step length and step width were all significantly different (p<0.0125) compared to straight gait. The turning ground reaction impulses were significantly greater (p<0.0125) compared to straight gait, indicating a need for increased support, medial shift, braking and propulsion. The turns to the left and right were statistically asymmetrical (p<0.0125) in 11 of the 18 variables. However, impulses were generally symmetrical, which does not generally support the functional asymmetry theory, though the contributions to propulsion were significantly greater when turning from the dominant limb.