computerized-dynamic-posturography-for-postural-control-assessment

Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication

Computerized dynamic posturography with the EquiTest is an objective technique for measuring postural strategies under challenging static and dynamic ...

University of Sydney

University of Hull

Fatigue in the legs is a problem experienced by skiers. It has been suggested that optimal orthotics may reduce muscle fatigue for a given movement task by minimising muscle activity (Med. Sci. Sports Exerc. 31 (1999) S421). The aims were to determine whether EMG would provide an independent method of analysing myoelectric fatigue in the vastus lateralis (VL) during a skier's squat and whether orthotics could affect this fatigue response. Six skiers performed skier's squats for as long as possible with no orthotic, low volume orthotics and high volume orthotics in their ski boots. Bipolar, active surface electrodes recorded EMG activity in the VL throughout each squat. Results for the EMG median frequency showed a significant shift in the power density spectrum towards the lower frequencies (P < 0.05) at the end of the contraction, suggesting that myoelectric fatigue was occurring and was measurable using EMG. All conditions displayed a significant decrease in median frequency at the end of the contraction (P = 0.001). The high volume orthotic showed a significant reduction in myoelectric fatigue, however, there was no difference in the duration of squats across the three conditions (P > 0.05). Subjective and objective findings support the use of the high volume foot orthotic for skiers.

The effect of foot orthotics on myoelectric fatigue in the vastus lateralis during a simulated skier's squat.

Transtibial amputees are at an increased risk of falling compared to age-matched, able-bodied individuals. The aim of this study was to compare the gait patterns of recent amputee fallers vs. non-fallers during level walking by investigating joint kinematics, kinetics and variability of temporal-spatial parameters. Eleven participants (fallers=6; non-fallers=5) walked along a 10-m walkway at their self-selected pace while three-dimensional kinematic and kinetic data were collected. The fallers had a significantly greater first peak vertical GRF (p=0.01) and load rate on the prosthetic limb than the non-fallers (p=0.03). Joint range of motion was similar between the two groups. Joint moment profiles were similar for the ankle and hip, with more noticeable differences at the knee. On the intact limb, the fallers also showed significantly smaller A1 and larger H2 power bursts and greater variability of swing time duration compared to the non-fallers. The non-fallers had a smaller load rate and knee moment that remained extensor suggesting they could make compensatory adjustments to maintain stability on the prosthetic side by modifying muscular demands of the knee extensors. This research suggests that falls prevention and prosthetic rehabilitation programmes should focus on improving knee muscle strength of the prosthetic limb, and eccentric ankle and hip strength of the intact limb, to improve stability and progression, particularly during weight transfer onto single support of the prosthetic limb.

Gait patterns in transtibial amputee fallers vs. non-fallers: biomechanical differences during level walking.

Physiotherapists routinely prescribe the use of two different early walking aids (EWAs) to individuals who have recently undergone unilateral transtibial amputation. No research to date has investigated the kinematic gait patterns of transtibial amputees walking with an EWA during early rehabilitation. The aim of the current RCT study was to compare gait patterns when walking with two different EWAs and whether either EWA provided patients with greater gait benefits.

Kinematic gait adaptations in unilateral transtibial amputees during rehabilitation.

To quantify postural responses in amputee fallers versus nonfallers by using computerized dynamic posturography.

Postural responses to dynamic perturbations in amputee fallers versus nonfallers: a comparative study with able-bodied subjects.

Stair walking relies on concentric contraction of the ankle plantarflexor and knee extensor muscles, which are either absent or weakened in transtibial amputees. As a result the risk of falling is increased in this population. The aim of this study was to compare the gait patterns of transtibial amputee fallers and non-fallers during stair ascent. Eleven participants (fallers = 6; non-fallers = 5) walked along a 3-m walkway and ascended a three-step staircase with handrails, at their self-selected pace, while three-dimensional kinematic data were collected from the lower limbs. A force plate was embedded into the first step and kinetic data were measured for the intact lead limb only. The fallers walked significantly faster (p = 0.00) and exhibited less hip flexion (p = 0.05) and less anterior pelvic tilt (p = 0.04) compared to the non-fallers. The fallers had significantly greater first and second peak vertical ground reaction force (GRF) on the intact limb than the non-fallers (p = 0.05 and p = 0.01, respectively) contributing to the significantly larger ankle (p = 0.02) and hip moments (p = 0.04). These findings suggested the amputee non-fallers performed mechanically demanding tasks more cautiously. Two of the participants self-selected a 'step to' gait pattern, ascending one step at a time. This may be considered a compensatory mechanism for the lack of ankle mobility and functional muscle performance in these two transtibial amputees.

Lower limb kinematic and kinetic differences between transtibial amputee fallers and non-fallers.

Intermittent claudication has been associated with impaired gait and balance. The study aim was to compare gait adaptations over time between claudicants classified with good versus poor balance. Kinematic data were collected from 24 claudicants during continuous walking. Balance was assessed using; Timed Up and Go test (TUG), and Sensory Organisation (SOT) and Motor Control (MCT) Tests using NeuroCom Equitest®. 'Good balance' (GB) was operationally defined as those claudicants achieving normal scores on at least 2 of 3 tests whereas 'poor balance' (PB) claudicants achieved normal scores on 0 or 1 test. Temporal-spatial and sagittal plane joint kinematics were analysed at three time intervals; 'no pain' (prior to onset), 'initial pain' and 'maximal pain' (unable to continue walking). A two-way mixed design ANOVA was performed. Claudicants demonstrated a significant decrease in walking speed, step frequency and increased time in double support (p<0.05). Inter-group analysis showed no differences between GB and PB on any temporal-spatial or kinematic parameters (p>0.05). There was no significant time and group interaction for any temporal-spatial or kinematic variable except hip flexion. GB claudicants demonstrated increased hip flexion as pain progressed but this adaptive strategy was not seen in PB claudicants. Claudicants make adaptations to walking by slowing (down) when in pain. Differences between GB and PB were not seen in temporal-spatial or ankle, knee and pelvic kinematic gait parameters. However adaptation to pain in GB claudicants involved a hip strategy, not seen in PB claudicants.

Kinematic adaptations to ischemic pain in claudicants during continuous walking.

To compare articulated and nonarticulated early walking aids (EWAs) for clinical and quality-of-life outcomes in transtibial amputees.

Hull early walking aid for rehabilitation of transtibial amputees--randomized controlled trial (HEART).

One-third of all elderly patients fall each year and impaired balance has been recognized as a specific risk factor. Intermittent claudication is common among the elderly population, affecting approximately 5% of the population over the age of 50. The aim of this proof-of-concept study was to assess the prevalence of impaired balance among elderly claudicants and to assess each patient's insight into their own risk of falling. A total of 58 claudicants (45 men), median age of 70 (interquartile range = 65-73) years, underwent objective balance assessment by using computerized dynamic posturography. As compared with 195 (5%) historic controls, 24 (41%) of the claudicants demonstrated abnormal balance when the Sensory Organization Test (SOT) was used. Vestibular dysfunction occurred in 52% of the claudicants. Abnormalities including somatosensory (22%), visual function (17%), and preferential reliance on inaccurate visual cues (17%) occurred less often. Prolonged Motor Control Test latency times were uncommon (n = 13) and were in most cases evenly distributed between those with normal (n = 7) and abnormal (n = 6) composite SOT scores. There was a significant difference in history of falling between claudicants with abnormal and normal SOT scores (p = 0.003), with a higher number of patients with abnormal SOT having experienced falling in the past year. However, no correlation between fear of falling and composite SOT score was found (Spearman rank correlation, r = 0.124; p = 0.381). Impaired balance, particularly secondary to vestibular problems, is very common among claudicants and may predispose to a high incidence of falls. Claudicants with abnormal balance are more likely to have a history of falls but not a fear of falling, thus potentially rendering these patients to be at a greater risk.

Computerized dynamic posturography in the objective assessment of balance in patients with intermittent claudication.

The management of peripheral arterial disease with intermittent claudication includes angioplasty, pharmaceutical therapy, risk factor modification and exercise therapy. Supervised exercise programmes are used sporadically but may improve the distance that an individual with claudication can walk. The purpose of this study was to evaluate the effectiveness of a 3-month supervised exercise programme on improving gait parameters in patients with intermittent claudication.

The effect of a 3-month supervised exercise programme on gait parameters of patients with peripheral arterial disease and intermittent claudication.

To determine whether increasing claudication severity is associated with impaired balance and physical functional ability.

Balance impairment, physical ability, and its link with disease severity in patients with intermittent claudication.

The aim of this study was to identify whether revascularization by percutaneous transluminal angioplasty (PTA) for patients with intermittent claudication improved measures of functional performance including balance.

Percutaneous transluminal angioplasty results in improved physical function but not balance in patients with intermittent claudication.

This study examined the longitudinal changes in generic health-related quality of life (QOL), prosthesis-related QOL, falls efficacy, and walking speed in men with lower-limb amputations up to 6 months following discharge from rehabilitation. Seven male unilateral transtibial amputees completed the Medical Outcomes Study 36-Item Short Form Health Survey, the Prosthesis Evaluation Questionnaire, and the Modified Falls Efficacy Scale at 1, 3, and 6 months postdischarge from rehabilitation. Walking speed was also recorded to objectively assess participants' mobility. Health-related QOL measures displayed increases, resulting in large effect sizes though not reaching statistical significance. Prosthesis-related QOL measures indicated that scales relating to the participants' prostheses improved and the support of significant others was the most positively scored variable. Walking speed increased by 0.12 m/s, although it was not significantly related to indices of QOL or falls efficacy. Falls efficacy did not improve significantly during the study period, although it was strongly related to QOL (p < 0.05). These results provide a novel insight into how QOL and falls efficacy develop in people with lower-limb amputations, alongside changes in mobility, after discharge from rehabilitation. Further improvements in physical health following discharge may be required to elicit subsequent increases in overall QOL and concurrent improvements in falls efficacy.

Temporal adaptations in generic and population-specific quality of life and falls efficacy in men with recent lower-limb amputations.

Background:Obstacle crossing is an important activity of daily living, necessary to avoid tripping or falling, although it is not fully understood how transtibial amputees adapt to performing this activity of daily living following discharge from rehabilitation.Objectives:The objective of this study was to investigate the longitudinal adaptations in obstacle crossing in transtibial amputees post-discharge from rehabilitation.Study design:Longitudinal repeated measures.Methods:Seven unilateral transtibial amputees crossed an obstacle 0.1m high positioned along a walkway while kinematic and kinetic data were recorded at 1, 3 and 6 months post-discharge.Results:At 6 months post-discharge, walking velocity had increased (0.17 m.s(-1)) with most participants self-selecting an intact lead limb preference. During swing phase, peak knee flexion (p = 0.03) and peak knee power absorption (K4; p = 0.01) were greater with an intact versus affected lead limb preference. Having crossed the obstacle, intact limb peak ankle power generation in pre-swing (A2; p = 0.01) and knee power absorption (K3; p = 0.05) during stance phase were greater when compared to the affected limb.Conclusions:Obstacle crossing improved, although a greater reliance on intact limb function was highlighted. Results suggested that further improvements to locomotor performance may be obtained by increasing affected limb knee range of motion and concentric and eccentric strength of the knee extensors and flexors.Clinical relevanceThe novel objective data from this study establish an understanding of how recent transtibial amputees adapt to performing obstacle crossing following discharge from rehabilitation. This allows for evidence-based clinical interventions to be developed, aimed at optimising biomechanical function, thus improving overall locomotor performance and perhaps subsequent quality of life.

Article	Year
The effect of foot orthotics on myoelectric fatigue in the vastus lateralis during a simulated skier's squat. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology\| PubMed ID: 15491844	2004
Gait patterns in transtibial amputee fallers vs. non-fallers: biomechanical differences during level walking. Gait & posture\| PubMed ID: 19071021	2009
Kinematic gait adaptations in unilateral transtibial amputees during rehabilitation. Prosthetics and orthotics international\| PubMed ID: 19367517	2009
Postural responses to dynamic perturbations in amputee fallers versus nonfallers: a comparative study with able-bodied subjects. Archives of physical medicine and rehabilitation\| PubMed ID: 19480879	2009
Lower limb kinematic and kinetic differences between transtibial amputee fallers and non-fallers. Prosthetics and orthotics international\| PubMed ID: 20450461	2010
Kinematic adaptations to ischemic pain in claudicants during continuous walking. Gait & posture\| PubMed ID: 20678939	2010
Hull early walking aid for rehabilitation of transtibial amputees--randomized controlled trial (HEART). Journal of vascular surgery\| PubMed ID: 20855178	2010
Computerized dynamic posturography in the objective assessment of balance in patients with intermittent claudication. Annals of vascular surgery\| PubMed ID: 20889294	2011
The effect of a 3-month supervised exercise programme on gait parameters of patients with peripheral arterial disease and intermittent claudication. Clinical biomechanics (Bristol, Avon)\| PubMed ID: 22663776	2012
Balance impairment, physical ability, and its link with disease severity in patients with intermittent claudication. Annals of vascular surgery\| PubMed ID: 23084732	2013
Percutaneous transluminal angioplasty results in improved physical function but not balance in patients with intermittent claudication. Journal of vascular surgery\| PubMed ID: 23880550	2013
Temporal adaptations in generic and population-specific quality of life and falls efficacy in men with recent lower-limb amputations. Journal of rehabilitation research and development\| PubMed ID: 23881768	2013
Longitudinal kinematic and kinetic adaptations to obstacle crossing in recent lower limb amputees. Prosthetics and orthotics international\| PubMed ID: 24150931	2013

Natalie Vanicek

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