Effects of walking speed on magnitude and symmetry of ground reaction forces in individuals with transfemoral prosthesis

Transfemoral prosthetic simulators versus amputees: ground reaction forces and spatio-temporal parameters in gait

This study aimed to compare the ground reaction forces (GRFs) and spatio-temporal parameters as well as their asymmetry ratios in gait between individuals wearing a transfemoral prosthetic simulator (TFSim) and individuals with unilateral transfemoral amputation (TFAmp) across a range of walking speeds (2.0-5.5 km h-1). The study recruited 10 non-disabled individuals using TFSim and 10 individuals with unilateral TFAmp using a transfemoral prosthesis. Data were collected using an instrumented treadmill with built-in force plates, and subsequently, the GRFs and spatio-temporal parameters, as well as their asymmetry ratios, were analysed. When comparing the TFSim and TFAmp groups, no significant differences were found among the gait parameters and asymmetry ratios of all tested metrics except the vertical GRFs. The TFSim may not realistically reproduce the vertical GRFs during the weight acceptance and push-off phases. The structural and functional variations in prosthetic limbs and components between the TFSim and TFAmp groups may be primary contributors to the difference in the vertical GRFs. These results suggest that TFSim might be able to emulate the gait of individuals with TFAmp regarding the majority of spatio-temporal and GRF parameters. However, the vertical GRFs of TFSim should be interpreted with caution.

Acutely Normalizing Walking Speed Does Not Normalize Gait Biomechanics Post-Anterior Cruciate Ligament Reconstruction

PURPOSE

To determine the effect of acutely increasing walking speed on gait biomechanics in ACLR individuals compared with their habitual speed and uninjured matched-controls.

METHODS

Gait biomechanics were collected on 30 ACLR individuals (20 females; age, 22.0 ± 4.2 yr; body mass index, 24.0 ± 3.0 kg·m -2 ) at their habitual speed and at 1.3 m·s -1 , a speed similar to controls, and 30 uninjured matched-controls (age: 21.9 ± 3.8, body mass index: 23.6 ± 2.5) at their habitual speed. Functional waveform analyses compared biomechanics between: i) walking at habitual speed vs 1.3 m·s -1 in ACLR individuals; and ii) ACLR individuals at 1.3 m·s -1 vs controls.

RESULTS

In the ACLR group, there were no statistically significant biomechanical differences between walking at habitual speed (1.18 ± 0.12 m·s -1 ) and 1.3 m·s -1 (1.29 ± 0.05 m·s -1 ). Compared with controls (habitual speed: 1.34 ± 0.12 m·s -1 ), the ACLR group while walking at 1.3 m·s -1 exhibited smaller vertical ground reaction force (vGRF) during early and late stance (13-28, 78-90% stance phase), greater midstance vGRF (47-61%), smaller early-to-midstance knee flexion angle (KFA; 1-44%), greater mid-to-late stance KFA (68-73, 96-101%), greater internal knee abduction moment (69-101%), and smaller internal knee extension moment (4-51, 88-96%).

CONCLUSIONS

Increasing walking speed to a speed similar to uninjured controls did not elicit significant changes to gait biomechanics, and ACLR individuals continued to demonstrate biomechanical profiles that are associated with PTOA development and differ from controls.

Kinetic adaptations of the intact limb in transfemoral amputees using a microprocessor prosthetic knee

BACKGROUND

In recent decades, high-tech prostheses, including microprocessor-controlled knee (MPK), have been developed to improve the functional abilities of lower limb amputees and to reduce gait asymmetry for the prevention of early joint degradation of the intact limb. The aim of this study was to determine the differences in joint moment and power of the intact limb of transfemoral amputees (TFAs) with an MPK compared to healthy individuals in 2 walking speed conditions.

METHODS

Twenty-one TFAs with MPK and matched 21 healthy individuals performed a walking task at spontaneous and rapid self-selected speeds. Spatiotemporal gait parameters and intact limb kinetic data were recorded.

RESULTS

The hip and knee moments in the frontal plane during rapid walking were not significantly higher than spontaneous walking in TFA group (respectively p = 0.08 and p = 0.48) and were lower than the control group. In the sagittal plane, the hip extensor moment in TFA was higher than the control group in the landing phase (p < 0.001 in both speed conditions).

SIGNIFICANCE

The kinetics of the intact limb of active TFAs with an MPK showed a significant reduction at the knee internal abductor moment compared to the control, potentially limiting risk factors for knee osteoarthritis. However, in the sagittal plane, higher hip extensor moments could favor low-back pain appearance. Gait analysis of lower limb amputees should thus be performed to highlight these kinetic adaptations and then help to propose the most relevant rehabilitation and prevention exercises to limit the appearance of early musculoskeletal degeneration.

Coordination of Lower Limb During Gait in Individuals With Unilateral Transfemoral Amputation

Understanding the lower-limb coordination of individuals with unilateral transfemoral amputation (uTFA) while walking is essential to understand their gait mechanisms. Continuous relative phase (CRP) analysis provides insights into gait coordination patterns of the neuromusculoskeletal system based on movement kinematics. Fourteen individuals with uTFA and their age-matched non-disabled individuals participated in this study. Kinematic data of the lower limbs of the participants were collected during walking. The joint angles, segment angles, and CRP values of the thigh-shank and shank-foot couplings were investigated. The curves among the lower limbs of the participants were compared using a statistical parametric mapping test. Compensatory strategies were found in the lower limbs from coordination patterns. In thigh-shank coupling, although distinct coordination traits in stance and swing phases among the lower limbs were found, the lower limbs in both groups were discovered to remain in a similar coordination pattern during gait. For individuals with uTFA, in shank-foot coupling, intact limbs demonstrated a short period of foot-leading pattern which was significantly different from that of the other limbs during mid-stance to compensate for the weaker force generation by prosthetic limbs. The findings offer normative coordination patterns on the walking of individuals with uTFA, which could benefit prosthetic gait rehabilitation and development.

Biomechanical responses of individuals with transtibial amputation stepping on a coronally uneven and unpredictable surface

Coronally uneven surfaces are prevalent in natural and man-made terrain, such as holes or bumps in the ground, curbs, sidewalks, and driveways. These surfaces can be challenging to navigate, especially for individuals with lower limb amputations. This study examined the biomechanical response of individuals with unilateral transtibial amputation (TTA) taking a step on a coronally uneven surface while wearing their clinically prescribed prosthesis, compared to individuals without mobility impairments (controls). An instrumented walkway was used with the middle force plate positioned either flush or rotated ± 15˚ in the coronal plane and concealed (blinded). TTAs used greater hip abduction compared to controls across all conditions, but especially during blinded inversion. The recovery step width of TTAs was wider after blinded eversion and narrower after blinded inversion, but unchanged for controls. These results suggest TTAs may have decreased balance control on unexpected, uneven surfaces. Additionally, TTAs generated less positive prosthetic ankle joint work during blinded inversion and eversion, and less negative coronal hip joint work during blinded inversion compared to controls. These biomechanical responses could lead to increased energy expenditure on uneven terrain. Surface condition had no effect on the vertical center of mass for either group of participants. Finally, the TTAs and the control group generated similar vertical GRF impulses, suggesting the TTAs had sufficient body support despite differences in surface conditions. These results are important to consider for future prosthetic foot designs and rehabilitation strategies.

Sprinting performance of individuals with unilateral transfemoral amputation: compensation strategies for lower limb coordination

Understanding the sprinting patterns of individuals with unilateral transfemoral amputation (uTFA) is important for designing improved running-specific prostheses and for prosthetic gait rehabilitation. Continuous relative phase (CRP) analysis acquires clues from movement kinematics and obtains insights into the sprinting coordination of individuals with uTFA. Seven individuals with uTFA sprinted on a 40 m runway. The spatio-temporal parameters, joint and segment angles of the lower limbs were obtained, and CRP analysis was performed on thigh-shank and shank-foot couplings. Subsequently, the asymmetry ratios of the parameters were calculated. Statistical analyses were performed between the lower limbs. Significant differences in the stance time, stance phase percentage, ankle joint angles and CRP of the shank-foot coupling (p < 0.05) were observed between the lower limbs. The primary contributor to these differences could be the structural differences between the lower limbs. Despite the presence of different coordination features in the stance and swing phases between the lower limbs, no significant difference in the coordination patterns of the thigh-shank coupling was observed. This may be a compensation strategy for achieving coordination patterns with improved symmetry between the lower limbs. The results of this study provide novel insights into the sprinting movement patterns of individuals with uTFA.