Medial-lateral centre of mass displacement and base of support are equally good predictors of metabolic cost in amputee walking

Amputees are known to walk with greater metabolic cost than able-bodied individuals and establishing predictors of metabolic cost from kinematic measures, such as centre of mass (CoM) motion, during walking are important from a rehabilitative perspective, as they can provide quantifiable measures to target during gait rehabilitation in amputees. While it is known that vertical CoM motion poorly predicts metabolic cost, CoM motion in the medial-lateral (ML) and anterior-posterior directions have not been investigated in the context of gait efficiency in the amputee population. Therefore, the aims of this study were to investigate the relationship between CoM motion in all three directions of motion, base of support and walking speed, and the metabolic cost of walking in both able-bodied individuals and different levels of lower limb amputee. 37 individuals were recruited to form groups of controls, unilateral above- and below-knee, and bilateral above-knee amputees respectively. Full-body optical motion and oxygen consumption data were collected during walking at a self-selected speed. CoM position was taken as the mass-weighted average of all body segments and compared to each individual’s net non-dimensional metabolic cost. Base of support and ML CoM displacement were the strongest correlates to metabolic cost and the positive correlations suggest increased ML CoM displacement or Base of support will reduce walking efficiency. Rehabilitation protocols which indirectly reduce these indicators, rather than vertical CoM displacement will likely show improvements in amputee walking efficiency

Temporal spatial and metabolic measures of walking in highly functional individuals with lower limb amputations

OBJECTIVE: The aim of this descriptive exploratory study is to record the temporal spatial parameters and metabolic energy expenditure during walking of individuals with amputation, walking with advanced prostheses and following completion of comprehensive rehabilitation, to able-bodied controls. DESIGN: Cross-sectional SETTING: Multi-disciplinary comprehensive rehabilitation centre PARTICIPANTS: Thirty severely injured United Kingdom military personnel with amputation and subsequent completion of their rehabilitation programme (10 unilateral trans-tibial, 10 unilateral trans-femoral, and 10 bilateral trans-femoral) were compared to (and of similar age, height and mass (p < 0.537) as) 10 able-bodied controls. INTERVENTIONS: Not applicable Main Outcomes and Measures: Temporal spatial and metabolic energy expenditure data were captured during walking on level ground at self-selected speed. RESULTS: The individuals with amputation were all male, with a mean age 29 years (SD = 4) and mean New Injury Severity Score of 31 (SD = 16). Walking speed, stride length, step length and cadence of individuals with a unilateral trans-tibial or trans-femoral amputation was comparable to controls, and only for individuals with a bilateral trans-femoral amputation was walking speed significantly slower (1·12m/s, p = 0.025) and cadence reduced (96 steps/min, p = 0.026). Oxygen cost for individuals with a unilateral trans-tibial amputation (0·15 ml/kg/m) was the same as for controls (0·15 ml/kg/m), and significantly increased by 20% (0·18ml/kg/m, p = 0.023) for unilateral trans-femoral and by 60% (0·24 ml/kg/m, p < 0.001) for bilateral trans-femoral individuals with amputation. CONCLUSION: The scientific literature reports a wide range of gait and metabolic energy expenditure across individuals with amputation. The results of this study indicate that the individuals with amputation have a gait pattern which is highly functional and efficient. This is comparable to a small number of studies reporting similar outcomes for individuals with a unilateral trans-tibial amputation, but the results from this study are better than those on individuals with trans-femoral amputations reported elsewhere, despite comparison with populations wearing similar prosthetic componentry. Those studies that do report similar outcomes have included individuals who have been provided with a comprehensive rehabilitation programme. This suggests that such a programme may be as important as, or even more important than, prosthetic component selection in improving metabolic energy expenditure. The data are made available as a benchmark for what is achievable in the rehabilitation of some individuals with amputations, but agreeably may not be possible for all amputees to achieve

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

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

Energy cost of ambulation in trans-tibial amputees using a dynamic-response foot with hydraulic versus rigid 'ankle': insights from body centre of mass dynamics.

BACKGROUND:Previous research has shown that use of a dynamic-response prosthetic foot (DRF) that incorporates a small passive hydraulic ankle device (hyA-F), provides certain biomechanical benefits over using a DRF that has no ankle mechanism (rigA-F). This study investigated whether use of a hyA-F in unilateral trans-tibial amputees (UTA) additionally provides metabolic energy expenditure savings and increases the symmetry in walking kinematics, compared to rigA-F. METHODS:Nine active UTA completed treadmill walking trials at zero gradient (at 0.8, 1.0, 1.2, 1.4, and 1.6 of customary walking speed) and for customary walking speed only, at two angles of decline (5° and 10°). The metabolic cost of locomotion was determined using respirometry. To gain insights into the source of any metabolic savings, 3D motion capture was used to determine segment kinematics, allowing body centre of mass dynamics (BCoM), differences in inter-limb symmetry and potential for energy recovery through pendulum-like motion to be quantified for each foot type. RESULTS:During both level and decline walking, use of a hyA-F compared to rigA-F significantly reduced the total mechanical work and increased the interchange between the mechanical energies of the BCoM (recovery index), leading to a significant reduction in the metabolic energy cost of locomotion, and hence an associated increase in locomotor efficiency (p < 0.001). It also increased inter-limb symmetry (medio-lateral and progression axes, particularly when walking on a 10° decline), highlighting the improvements in gait were related to a lessening of the kinematic compensations evident when using the rigA-F. CONCLUSIONS:Findings suggest that use of a DRF that incorporates a small passive hydraulic ankle device will deliver improvements in metabolic energy expenditure and kinematics and thus should provide clinically meaningful benefits to UTAs' everyday locomotion, particularly for those who are able to walk at a range of speeds and over different terrains

Comparison between microprocessor-controlled ankle/foot and conventional prosthetic feet during stair negotiation in people with unilateral transtibial amputation

Contrary to stance-phase dorsiflexion of conventional prosthetic feet, the microprocessor-controlled Proprio foot permits swing-phase dorsiflexion on stairs. The purpose of this study was to compare Symmetry in External Work (SEW) between a microprocessor-controlled foot and conventional prosthetic feet in two groups with unilateral transtibial amputation (Medicare Functional Classification Levels K-Level-2 and K-Level-3) during stair ascent and descent. Ten subjects were evaluated while wearing three conventional prosthetic feet- solid ankle cushion heel (SACH), stationary attachment flexible endoskeleton (SAFE), and Talux-and the Proprio foot using a study socket and were given a 10- to 14-day accommodation period with each foot. Ground reaction forces were collected using F-scan sensors during stair ascent and descent. The SEW between the intact and amputated limbs was calculated for each foot. During stair ascent, the Proprio foot resulted in a higher interlimb symmetry than conventional prosthetic feet, with significant differences between the Pro prio and SACH/SAFE feet. The swing-phase dorsiflexion appeared to promote greater interlimb symmetry because it facilitated forward motion of the body, resulting in a heel-to-toe center of pressure trajectory. During stair descent, all feet had low symmetry without significant differences between feet. The movement strategy used when descending stairs, which is to roll over the edge of a step, had a greater influence on symmetry than the dorsiflexion features of prosthetic feet