Effects of neuromuscular electrical stimulation on gait performance in chronic stroke with inadequate ankle control - A randomized controlled trial.

Neuromuscular electrical stimulation (NMES) has been used to improve muscle strength and decrease spasticity of the ankle joint in stroke patients. However, it is unclear how NMES could influence dynamic spasticity of ankle plantarflexors and gait asymmetry during walking. The study aimed to evaluate the effects of applying NMES over ankle dorsiflexors or plantarflexors on ankle control during walking and gait performance in chronic stroke patients. Twenty-five stroke participants with inadequate ankle control were recruited and randomly assigned to an experimental or a control group. The experimental group received 20 minutes of NMES on either the tibialis anterior muscle (NMES-TA) or the medial gastrocnemius muscle (NMES-MG). The control group received 20 minutes of range of motion and stretching exercises. After the 20 minutes of NMES or exercises, all participants received ambulation training for 15 minutes. Training sessions occurred 3 times per week for 7 weeks. The pre- and post-training assessments included spatio-temporal parameters, ankle range of motion, and dynamic spasticity of ankle plantarflexors during walking. Muscle strength of ankle dorsiflexors and plantarflexors as well as static spasticity of ankle plantarflexors were also examined. The results showed that the static and dynamic spasticity of ankle plantarflexors of the NMES-TA group were significantly decreased after training. Reduction in dynamic spasticity of ankle plantarflexors of the NMES-TA group was significantly greater than that of the NMES-MG group. When compared to the control group, the NMES-TA group had greater improvements in spatial asymmetry, ankle plantarflexion during push off, and muscle strength of ankle dorsiflexors, and the NMES-MG group showed a significant decrease in temporal asymmetry. In summary, NMES on ankle dorsiflexors could be an effective management to enhance gait performance and ankle control during walking in chronic stroke patients. NMES on ankle plantarflexors may improve gait symmetry.

Biomechanical evaluation of a novel pedicle screw-based interspinous spacer: A finite element analysis.

Interspinous spacers have been designed to provide a minimally invasive surgical technique for patients with lumbar spinal stenosis or foraminal stenosis. A novel pedicle screw-based interspinous spacer has been developed in this study, and the aim of this finite element experiment was to investigate the biomechanical differences between the pedicle screw-based interspinous spacer (M-rod system) and the typical interspinous spacer (Coflex-F™). A validated finite element model of an intact lumbar spine was used to analyze the insertions of the Coflex-F™, titanium alloy M-rod (M-Ti), and polyetheretherketone M-rod (M-PEEK), independently. The range of motion (ROM) between each vertebrae, stiffness of the implanted level, the peak stress at the intervertebral discs, and the contact forces on spinous process were analyzed. Of all three devices, the Coflex-F™ provided the largest restrictions in extension, flexion and lateral bending. For intervertebral disc, the peak stress at the implanted segment decreased by 81% in the Coflex-F™, 60.2% in the M-Ti and 46.7% in the M-PEEK when compared to the intact model. For the adjacent segments, while the Coflex-F™ caused considerable increases in the ROM and disc stress, the M-PEEK only had small changes.

Age-related differences in inter-joint coordination during stair walking transitions.

Stair negotiation is one of the most difficult and hazardous locomotor tasks for older adults with fall-related accidences reported frequently. Since knowledge about inter-joint coordination during stair walking provides insights to age-related changes in neuromuscular control of gait that can inform prevention or intervention strategies, the current study investigated the effect of age on the pattern and variability of inter-joint coordination during stair-floor transitions during gait. Gait and motion analyses of the lower extremities of 20 young and 20 older adults during floor to stair (F-S) and stair to floor (S-F) walking transitions provided continuous measures of relative phase (CRP) that assessed inter-joint coordination of the hip, knee, and angle joints. The mean absolute relative phase (MARP) and deviation phase (DP) provided descriptive metrics for CRP pattern and variability respectively. For hip-knee CRP pattern, older adults demonstrated significantly smaller MARP than young adults in stance and most swing phases during F-S and S-F. For knee-ankle, older adults showed a significant smaller MARP of the trailing limb during S-F than young adults. In most stance and swing phases, the hip-knee DP values of older adults were significantly lower than that of young adults. Significant lower knee-ankle DP values of older adults were only detected in swing phase during S-F. The findings suggest that normal aging adults have less independent control of adjacent joints compared to younger adults suggesting they have less flexibility to modulate inter-joints coordination appropriately during stair walking transitions.

Investigating gait adjustments and body sway while walking across wooden scaffold boards.

The flexible wooden boards are still being used on the scaffolds at some construction worksites in China. We examined if the board dimension, acclimation phase and construction work experience influence workers' walking strategies on these boards. Among the 40 construction workers recruited, half of them had more than 1 year of construction work experience. The participants' body sway and the gait adjustments were captured and analysed. Our analysis showed the width and thickness of the boards had significant effects on walking speed. There is a significant interaction between construction experience and board width on stride width, whereas the interaction between construction experience and acclimation phase affects step length and walking speed. The body sway at the C6/C7 and L5/S1 locations are significantly affected by most of the factors. We also found that once the participants acclimated to the board condition, the sway variability increased. Practitioner Summary: This study investigated gait and postural adjustments of workers with different construction experience while walking over wooden scaffold boards, which is one of the activities highly associated with falling accidents in China.

Inter-joint coordination of overground versus treadmill walking in young adults.

This study compares the pattern and variability of inter-joint coordination between treadmill and overground walking. Gait analyses of five young adults were performed during preferred speed overground walking (GPS), preferred speed treadmill walking (TPS), and treadmill walking with overground preferred speed (TGS). Continuous relative phase (CRP), derived from the phase portraits of two adjacent joints, was used to examine the inter-joint coordination. Cross-correlation measures and root-mean-square (RMS) differences were used to compare CRP patterns of the GPS condition to those of TPS and TGS conditions respectively. The deviation phase (DP) was used to evaluate the variability of inter-joint coordination during the stance and swing phases over a gait cycle for each condition. The walking speed of TPS was significantly slower than those of GPS and TGS. For the hip-knee CRP pattern, the RMS differences between GPS and TPS were significantly greater than the RMS differences between GPS and TGS. No significant differences between conditions were detected for the cross-correlation measures of hip-knee and knee-ankle CRP patterns. During the stance phase, the hip-knee DP values of TGS were significantly smaller than that of GPS and the knee-ankle DP values of TGS were also significantly smaller than that of GPS and TPS. No significant differences were detected for all three conditions in the swing phase. The findings suggest that the treadmill imposes a systemic regulation on dynamic neuromuscular control during walking, which may need to be considered while interpreting treadmill-based analysis of training to overground walking.

Concussion induces gait inter-joint coordination variability under conditions of divided attention and obstacle crossing.

This study investigated the effect of concussion on the pattern and variability of inter-joint coordination during level walking (Level), obstacle crossing (OB), and walking with a concurrent cognitive test (ATT). Gait analyses of 23 concussed and 23 matched healthy adults were performed. Continuous relative phase (CRP), derived from phase angles of two adjacent joints, was used to assess inter-joint coordination. Cross-correlation measures and root-mean-square (RMS) differences were used to compare CRP patterns of the Level condition to those of OB and ATT conditions, respectively. Deviation phase (DP) was used to evaluate variability of inter-joint coordination for each task. For hip-knee and knee-ankle CRP patterns, RMS differences between OB and Level and between ATT and Level in concussed subjects were significantly greater than those of healthy adults. No significant group differences were detected for the cross-correlation measures of hip-knee and knee-ankle CRP patterns. In stance phase, a significant task effect on DP values was detected in hip-knee inter-joint coordination. For knee-ankle inter-joint coordination, concussed subjects showed significantly greater DP values than healthy controls during OB and ATT. In swing phase, concussed individuals showed greater DP values in hip-knee and knee-ankle inter-joint coordination compared to healthy controls. The findings suggest that the ability to modulate inter-joint coordination patterns when accommodating to gait perturbations is affected by concussion.

Variability in inter-joint coordination during walking of elderly adults and its association with clinical balance measures.

BACKGROUND: Walking requires coordination among multiple joints. Little is known about the association between the coordination ability and fall risks in elderly adults. This study investigated variability of inter-joint coordination in elderly adults and determined its correlation to clinical balance measures. METHODS: Gait analyses of 15 non-fallers and 15 fallers were performed during walking. Continuous relative phase, derived from phase angles of two adjacent joints, was used to assess the inter-joint coordination. Variability of inter-joint coordination was calculated as the average standard deviation of all points on the ensemble continuous relative phase curve over a gait cycle, namely the deviation phase. Outcomes from three clinical balance tests, including Berg Balance Test, Dynamic Gait Index and Timed Up-and-Go, were examined. FINDINGS: No significant group differences were detected in hip-knee deviation phase values after accounting for differences in walking speeds. For the knee-ankle deviation phase, fallers demonstrated significantly greater values in the stance phase but smaller values in the swing phase. The hip-knee deviation phase values demonstrated a negative correlation with Dynamic Gait Index, and the knee-ankle deviation phase values had a negative correlation with Dynamic Gait Index and a positive correlation with Timed Up-and-Go time. INTERPRETATION: Excessive variability of the supporting limb and reduced variability of the swing limb in knee-ankle inter-joint coordination of fallers may contribute to their risk of imbalance or tripping during walking. Compared to Berg Balance Test and Timed Up-and-Go, Dynamic Gait Index scores might be more sensitive to reflect declines in inter-joint coordination during walking.

Effect of walking speed on inter-joint coordination differs between young and elderly adults.

Investigating inter-joint coordination at different walking speeds in young and elderly adults could provide insights to age-related changes in neuromuscular control of gait. We examined effects of walking speed and age on the pattern and variability of inter-joint coordination. Gait analyses of 10 young and 10 elderly adults were performed with different self-selected speeds, including a preferred, faster, and slower speed. Continuous relative phase (CRP), derived from phase planes of two adjacent joints, was used to assess the inter-joint coordination. CRP patterns were examined with cross-correlation measures and root-mean-square (RMS) differences when comparing ensemble mean curves of the faster or slower speed to preferred speed walking. Variability of coordination for each participant was assessed with the average value of all standard deviations calculated for each data point over a gait cycle from all CRP curves, namely the deviation phase (DP). For hip-knee CRP pattern, RMS differences were significantly greater between the slower and preferred walking speeds than between the faster and preferred walking speeds in young adults, but this was not found in elderly adults. Significant group differences in RMS differences and cross-correlation measures were detected in hip-knee CRP patterns between the slower and preferred walking speeds. No significant walking speed or age effects were detected for the knee-ankle CRP. Significant walking speed effects were also detected in hip-knee DP values. However, no significant group differences were detected for all three speeds. These findings suggested that young and elder adults compromise changes of walking speed with different neuromuscular control strategies.

Altered inter-joint coordination during walking in patients with total hip arthroplasty.

The purpose of this study was to investigate the pattern and variability of inter-joint coordination for both surgical and non-surgical limbs during walking in patients before and after total hip arthroplasty (THA). Gait analysis of THA patients (n=20) and age-matched controls (n=10) was performed. THA patients were tested at pre-surgery, 6-week and 16-week post surgery. Continuous relative phase (CRP) was used to assess the inter-joint coordination pattern and variability. Variability of coordination for each subject was calculated over a gait cycle with the deviation phase (DP). Between-subject group differences in CRP patterns were examined with cross-correlation measures and root-mean-square (RMS) differences. The surgical limb demonstrated significantly higher DP values comparing to the controls at pre-surgery. Compared to pre-surgery, significant time effects on THA patients were detected in hip-knee DP values at 16-week post surgery for both limbs, and in knee-ankle DP values at 16-week post surgery for the surgical limb. RMS differences for hip-knee and knee-ankle CRP decreased gradually after surgery for both limbs. Cross-correlation measures were overall strong for CRP patterns of both limbs, with r(2) values greater than 0.94. Our results suggested that both hip-knee and knee-ankle coordination, especially the surgical limb, were altered with a higher variability to compromise the deteriorated hip joint. Asymmetric changes in accommodations and variability of bilateral lower extremities may contribute to the residual gait problems observed in THA patients. Therefore, clinical efforts may exert to improve the inter-joint coordination in this population.