Lower Extremity Joint Contributions to Trunk Control During Walking in Persons with Transtibial Amputation

A Passive Polycentric Mechanism to Improve Active Mediolateral Balance in Prosthetic Walking

Prosthetic legs are typically passive systems without active ankle control, restricting mediolateral balancing to a hip strategy. Resulting balance control impairments for persons with a lower extremity amputation may be mitigated by increasing hip strategy effectiveness, in which relatively small hip moments of force are adequate for mediolateral balancing. To increase hip strategy effectiveness we have developed a prosthetic leg prototype based on the Peaucellier mechanism, the Sideways Balance Mechanism (SBM). This polycentric mechanism adds a frontal plane degree of freedom, reducing mediolateral body displacements. Adding a passive joint alone introduces instability, in which mediolateral body rotation leads to CoM height loss, ultimately resulting in a fall. The SBM however provides stability typically absent by lengthening under rotation, thereby compensating for CoM height loss. By allowing for both foot rotation (in-/eversion), and increased mediolateral ground reaction force the SBM increases hip strategy effectiveness. We aimed to provide proof of principle that the SBM can improve active mediolateral balance control in prosthetic walking by increasing hip strategy effectiveness compared to a typical set-up. Comparison between a typical set-up and the SBM showed an increased mediolateral ground reaction force at equal hip moments of force for a 2D forwards dynamics computer simulation, and a reduced hip moment of force at equal mediolateral ground reaction force for a case study. Results validate increased hip strategy effectiveness of the SBM compared to a typical set-up, providing proof of principle that adding an SBM to a prosthetic set-up improves mediolateral balance control in prosthetic walking.

A novel balance training approach: Biomechanical study of virtual reality-based skateboarding

Introduction: The use of virtual reality (VR) technology in training and rehabilitation gained increasing attention in recent years due to its potential to provide immersive and interactive experiences. We developed a novel VR-based balance training, VR-skateboarding, for improving balance. It is important to investigate the biomechanical aspects of this training, as it would have benefited both health professionals and software engineers. Aims: This study aimed to compare the biomechanical characteristics of VR-skateboarding with those of walking. Materials and Methods: Twenty young participants (10 males and 10 females) were recruited. Participants underwent VR-skateboarding and walking at the comfortable walking speed, with the treadmill set at the same speed for both tasks. The motion capture system and electromyography were used to determine joint kinematics and muscle activity of the trunk and legs, respectively. The force platform was also used to collect the ground reaction force. Results: Participants demonstrated increased trunk flexion angles and muscle activity of trunk extensor during VR-skateboarding than during walking (p < 0.01). For the supporting leg, participants' joint angles of hip flexion and ankle dorsiflexion, as well as muscle activity of knee extensor, were higher during VR-skateboarding than during walking (p < 0.01). For the moving leg, only hip flexion increased in VR-skateboarding when compared to walking (p < 0.01). Furthermore, participants increased weight distribution in the supporting leg during VR-skateboarding (p < 0.01). Conclusion: VR-skateboarding is a novel VR-based balance training that has been found to improve balance through increased trunk and hip flexion, facilitated knee extensor muscles, and increased weight distribution on the supporting leg compared to walking. These differences in biomechanical characteristics have potential clinical implications for both health professionals and software engineers. Health professionals may consider incorporating VR-skateboarding into training protocols to improve balance, while software engineers may use this information to design new features in VR systems. Our study suggests that the impact of VR-skateboarding particularly manifest when focusing on the supporting leg.

Effect of Unilateral Knee Extension Restriction on the Lumbar Region during Gait

Unilateral knee extension restriction might change trunk alignment and increase mechanical load on the lumbar region during walking. We aimed to clarify lumbar region mechanical load during walking with restricted knee extension using a musculoskeletal model simulation. Seventeen healthy adult males were enrolled in this study. Participants walked 10 m at a comfortable velocity with and without restricted right knee extension of 15° and 30° using a knee brace. L4-5 joint moment, joint reaction force, and muscle forces around the lumbar region during walking were calculated for each condition. Peaks of kinetic data were compared among three gait conditions during 0%-30% and 50%-80% of the right gait cycle. Lumbar extension moment at early stance of the bilateral lower limbs was significantly increased in the 30° restricted condition (p ≤ 0.021). Muscle force of the multifidus showed peaks at stance phase of the contralateral side during walking, and the erector spinae showed force peaks at early stance of the bilateral lower limb. Muscle force of the multifidus and erector spinae increased with increasing degree of knee flexion (p ≤ 0.010), with a large effect size (η ² = 0.273-0.486). The joint force acting on L4-5 showed two peaks at early stance of the bilateral lower limbs during the walking cycle. The anterior and vertical joint force on L4-5 increased by 14.2%-36.5% and 10.0%-23.0% in walking with restricted knee extension, respectively (p ≤ 0.010), with a large effect size (η ² = 0.149-0.425). Restricted knee joint extension changed trunk alignment and increased the muscle force and the vertical and anterior joint force on the L4-5 joint during walking; this tendency became more obvious with increased restriction angle. Our results provide important information for therapists engaged in the rehabilitation of patients with knee contracture.

Assessment of biomechanical deficits in individuals with a trans-tibial amputation during level gait using one-dimensional statistical parametric mapping

BACKGROUND

Most previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping.

RESEARCH QUESTION

What are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur?

METHODS

Eight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping.

RESULTS

More ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase.

SIGNIFICANCE

Using a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.