Effects of robotic postural stand training with epidural stimulation on sitting postural control in individuals with spinal cord injury: a pilot study

(1) Background. High-level spinal cord injury (SCI) disrupts trunk control, leading to an impaired performance of upright postural tasks in sitting and standing. We previously showed that a novel robotic postural stand training with spinal cord epidural stimulation targeted at facilitating standing (Stand-scES) largely improved standing trunk control in individuals with high-level motor complete SCI. Here, we aimed at assessing the effects of robotic postural stand training with Stand-scES on sitting postural control in the same population. (2) Methods. Individuals with cervical (n = 5) or high-thoracic (n = 1) motor complete SCI underwent approximately 80 sessions (1 h/day; 5 days/week) of robotic postural stand training with Stand-scES, which was performed with free hands (i.e., without using handlebars) and included periods of standing with steady trunk control, self-initiated trunk and arm movements, and trunk perturbations. Sitting postural control was assessed on a standard therapy mat, with and without scES targeted at facilitating sitting (Sit-scES), before and after robotic postural stand training. Independent sit time and trunk center of mass (CM) displacement were assessed during a 5 min time window to evaluate steady sitting control. Self-initiated antero-posterior and medial-lateral trunk movements were also attempted from a sitting position, with the goal of covering the largest distance in the respective cardinal directions. Finally, the four Neuromuscular Recovery Scale items focused on sitting trunk control (Sit, Sit-up, Trunk extension in sitting, Reverse sit-up) were assessed. (3) Results. In summary, neither statistically significant differences nor large Effect Size were promoted by robotic postural stand training for the sitting outcomes considered for analysis. (4) Conclusions. The findings of the present study, together with previous observations, may suggest that robotic postural stand training with Stand-scES promoted trunk motor learning that was posture- and/or task-specific and, by itself, was not sufficient to significantly impact sitting postural control

SHORT STEP KNEE OSTEOARTHRITIS: A BEGINNERS GUIDE TO RUNNING POST ACLR

Introduction: Post anterior cruciate ligament reconstruction (ACLR), individuals are 3-4x more likely to develop knee osteoarthritis (OA). Increased knee joint loads, and knee joint loading characteristics have been associated with knee OA. Specifically, peak loads, cumulative loads, and loading rate loads about the knee have been associated with the onset and progression of knee OA. Running increases the magnitude of these loads and an estimated 90% of individual's participant in lower levels of activity such as running post ACLR. Changes in cartilage morphology that are seen as early as 4 months post ACL injury may suggest the cartilages inability to manage high cyclical loads associated with running. Thus, promoting interventions to decrease joint loads during running post ACLR may prevent or impede degenerative joint changes. Decreasing step length has been shown to decrease knee forces within the healthy population but due to gait changes seen post ACLR, it is unclear if these reductions will be seen among the ACLR population. Between limb kinematic differences have also been seen, but no study has compared joint loads between limbs post ACLR. The further understanding of how the two limbs interact post ACLR may improve clinical recommendations. The first purpose of this study was to test for changes in tibiofemoral joint (TFJ) and patellofemoral (PFJ) loading parameters as individuals with a history of unilateral ACLR run with a shorter step length. The secondary purpose was to compare PFJ and TFJ loading parameters during running. Variables of interest include peak force, force*time impulse, impulse per km, and average loading rate. Methods: Eighteen individuals ( =22 years) with unilateral ACLR reconstruction 2 to 7 years prior were recruited for the study. Lower extremity gait analysis was conducted using a motion capture system and instrumented treadmill. Participants ran at their preferred speed ( =2.65 m/s) and preferred step length, followed by a 5% and 10% decreased step length condition. Two separate Two-Way analysis of variance were used to test for linear trends across step length conditions (3 factor) and between limb differences (2 factor). Least significant difference tests were used to analyze differences between step length conditions. Results: Linear trends were observed across step length conditions for PFJ, TFJ, and mTFJ peak force (all p [less than] 0.000), PFJ, TFJ, and mTFJ impulse (all p [less than] 0.000), and PFJ, TFJ, and mTFJ impulse per km (all p [less than] 0.012). A 5% and 10% decrease in step length were successful in reducing peak joint force, force*time impulse, and impulse per km by 4 to 12%. Between limb differences were observed. The experimental limb experienced a 7% decreased force*time impulse and impulse per km within the TFJ. Conclusion: Individuals with ACLR who ran with a shorter step length reduced peak force, force*time impulse, and cumulative impulse per km within the PFJ, TFJ, and mTFJ compartment, and these reductions had a linear trend from preferred step length, a 5% decrease, and a 10% decrease. Between limb loading differences were seen within the TFJ. Future longitudinal studies to examine this running modification's effect on knee joint cartilage thickness and health post ACLR appear justified

Aging, Gait Variability, and Adaptability

The purpose of this work was to study the relationships between age, measures of gait variability, and locomotor adaptability. Measures of gait variability are used to identify maladapted locomotor behavior, motor disease, and risk of falls. The first aim was to determine the relationships between age and measures of gait variability. Thirty-four participants (23-71 years old) walked on a treadmill for 6 minutes at their preferred speed. Variability of stride times and lengths was computed via linear measures (standard deviation and coefficient of variation) and nonlinear measures (sample entropy and detrended fluctuation analysis). Movement trajectory variability of the dominant knee angle, and vertical and medial-lateral positions of the pelvis were quantified using nonlinear measures (correlation dimension and local dynamic stability). The results showed little association of age and variability measures. Additional analyses revealed that preferred gait speed was a better predictor of gait variability measures, suggesting that variations in gait variability are driven more by preferred gait speed than age. The second aim of this dissertation was to investigate the relationships between measures of gait variability. While the relationships between measures of gait variability have received little investigation, many have been suggested to quantify the same underlying component of locomotion, the ability of an individual to adapt. A principal component analysis was performed to examine if measures of variability were related to one or more underlying constructs of gait variability. Four independent constructs of gait variability were identified, indicating there is no single construct underlying gait variability and different variability measures can be associated with the same constructs. The final aim was to determine if measures of variability quantify the ability of an individual to adapt to a novel split-belt gait adaptation task, where two treadmill belts were set at different speeds. The findings showed no significant association between measures of gait variability from the preferred walking trial and adaptability performance. To conclude, gait variability is more speed-related than age-related, measures of gait variability quantify at least four separate components of gait, and gait variability measures are relatively unrelated to the adaptability performance of an individual

Design and Validation of a Passive Ankle Foot Orthosis (AFO) with Ankle Power Biofeedback Capability for Individuals with Cerebral Palsy (CP)

This study seeks to primarily investigate whether our designed passive AFO used in conjunction with biofeedback can improve ankle plantar flexor muscle recruitment compared to shod (baseline) or AFO. Its secondary goals are to evaluate whether muscle recruitment improvements are comparable to those seen with a powered ankle exoskeleton. Another secondary goal will be to compare ankle power between all condition

SHORT STEP KNEE OSTEOARTHRITIS: A BEGINNERS GUIDE TO RUNNING POST ACLR

Introduction: Post anterior cruciate ligament reconstruction (ACLR), individuals are 3-4x more likely to develop knee osteoarthritis (OA). Increased knee joint loads, and knee joint loading characteristics have been associated with knee OA. Specifically, peak loads, cumulative loads, and loading rate loads about the knee have been associated with the onset and progression of knee OA. Running increases the magnitude of these loads and an estimated 90% of individual's participant in lower levels of activity such as running post ACLR. Changes in cartilage morphology that are seen as early as 4 months post ACL injury may suggest the cartilages inability to manage high cyclical loads associated with running. Thus, promoting interventions to decrease joint loads during running post ACLR may prevent or impede degenerative joint changes. Decreasing step length has been shown to decrease knee forces within the healthy population but due to gait changes seen post ACLR, it is unclear if these reductions will be seen among the ACLR population. Between limb kinematic differences have also been seen, but no study has compared joint loads between limbs post ACLR. The further understanding of how the two limbs interact post ACLR may improve clinical recommendations. The first purpose of this study was to test for changes in tibiofemoral joint (TFJ) and patellofemoral (PFJ) loading parameters as individuals with a history of unilateral ACLR run with a shorter step length. The secondary purpose was to compare PFJ and TFJ loading parameters during running. Variables of interest include peak force, force*time impulse, impulse per km, and average loading rate. Methods: Eighteen individuals ( =22 years) with unilateral ACLR reconstruction 2 to 7 years prior were recruited for the study. Lower extremity gait analysis was conducted using a motion capture system and instrumented treadmill. Participants ran at their preferred speed ( =2.65 m/s) and preferred step length, followed by a 5% and 10% decreased step length condition. Two separate Two-Way analysis of variance were used to test for linear trends across step length conditions (3 factor) and between limb differences (2 factor). Least significant difference tests were used to analyze differences between step length conditions. Results: Linear trends were observed across step length conditions for PFJ, TFJ, and mTFJ peak force (all p [less than] 0.000), PFJ, TFJ, and mTFJ impulse (all p [less than] 0.000), and PFJ, TFJ, and mTFJ impulse per km (all p [less than] 0.012). A 5% and 10% decrease in step length were successful in reducing peak joint force, force*time impulse, and impulse per km by 4 to 12%. Between limb differences were observed. The experimental limb experienced a 7% decreased force*time impulse and impulse per km within the TFJ. Conclusion: Individuals with ACLR who ran with a shorter step length reduced peak force, force*time impulse, and cumulative impulse per km within the PFJ, TFJ, and mTFJ compartment, and these reductions had a linear trend from preferred step length, a 5% decrease, and a 10% decrease. Between limb loading differences were seen within the TFJ. Future longitudinal studies to examine this running modification's effect on knee joint cartilage thickness and health post ACLR appear justified

Robotic Postural Training With Epidural Stimulation for the Recovery of Upright Postural Control in Individuals With Motor Complete Spinal Cord Injury: A Pilot Study

Activity-based training and lumbosacral spinal cord epidural stimulation (scES) have the potential to restore standing and walking with self-balance assistance after motor complete spinal cord injury (SCI). However, improvements in upright postural control have not previously been addressed in this population. Here, we implemented a novel robotic postural training with scES, performed with free hands, to restore upright postural control in individuals with chronic, cervical ( = 5) or high-thoracic ( = 1) motor complete SCI, who had previously undergone stand training with scES using a walker or a standing frame for self-balance assistance. Robotic postural training re-enabled and/or largely improved the participants\u27 ability to control steady standing, self-initiated trunk movements and upper limb reaching movements while standing with free hands, receiving only external assistance for pelvic control. These improvements were associated with neuromuscular activation pattern adaptations above and below the lesion. These findings suggest that the human spinal cord below the level of injury can generate meaningful postural responses when its excitability is modulated by scES, and can learn to improve these responses. Upright postural control improvements can enhance functional motor recovery promoted by scES after severe SCI