Joanne E. Wittwer

Gait variability in community dwelling adults with Alzheimer disease.

Studies have shown that measures of gait variability are associated with falling in older adults. However, few studies have measured gait variability in people with Alzheimer disease, despite the high incidence of falls in Alzheimer disease. The purpose of this study was to compare gait variability of community-dwelling older adults with Alzheimer disease and control subjects at various walking speeds. Ten subjects with mild-moderate Alzheimer disease and ten matched control subjects underwent gait analysis using an electronic walkway. Participants were required to walk at self-selected slow, preferred, and fast speeds. Stride length and step width variability were determined using the coefficient of variation. Results showed that stride length variability was significantly greater in the Alzheimer disease group compared with the control group at all speeds. In both groups, increases in walking speed were significantly correlated with decreases in stride length variability. Step width variability was significantly reduced in the Alzheimer disease group compared with the control group at slow speed only. In conclusion, there is an increase in stride length variability in Alzheimer disease at all walking speeds that may contribute to the increased incidence of falls in Alzheimer disease.

Gait Patterns After Anterior Cruciate Ligament Reconstruction Are Related to Graft Type

Background Although there is a tendency toward gait normalization after anterior cruciate ligament reconstruction, altered moments about the knee flexion-extension axis have been reported. It is possible that these gait alterations relate to donor site morbidity associated with the graft harvest. Hypothesis There is a relationship between graft type and external knee moments during walking. Study Design Controlled laboratory study. Methods Three groups were compared: 17 patellar tendon anterior cruciate ligament reconstruction patients (mean, 11 months after surgery), 17 hamstring tendon anterior cruciate ligament reconstruction patients (mean, 9.3 months after surgery), and 17 matched controls. A 3-dimensional motion analysis and force plate system was used to determine sagittal plane kinematics and kinetics of the lower limb during comfortable-speed walking. Results There were significant differences in the moments about the knee that related to graft type. The external knee flexion moment at midstance was significantly smaller than that in the control knees in 65% of patients in the patellar tendon group and 29% of patients in the hamstring tendon group. In contrast, the external knee extension moment at terminal stance was significantly smaller than that in the control knees in 53% of subjects in the hamstring tendon group and 23% of subjects in the patellar tendon group. Conclusions There are graft-specific differences in knee biomechanics after anterior cruciate ligament reconstruction that appear to relate to the donor site. Clinical Relevance Considerable debate continues as to whether the patellar tendon or the hamstring tendon graft is preferable for anterior cruciate ligament reconstruction. It is therefore clinically relevant to understand the biomechanical differences in knee function associated with both graft types.

Test-retest reliability of spatial and temporal gait parameters of people with Alzheimer's disease.

The reliability of measures of walking in people with Alzheimers disease (AD) has not been established despite the increased variability of their walking compared to control groups. The purpose of this study was to examine the test-retest reliability of temporal and spatial gait measurements in community dwelling people with AD. Ten males and 10 females with AD completed 10 walks on an instrumented walkway at self-selected comfortable speed on two occasions, 1 week apart. Data from 10 walks for each subject for each session were averaged and test-retest reliability of velocity, cadence, step length, stride length, step width, toe in/out angle, swing and stance times was measured using intraclass correlation coefficients (ICCs) of the type (3, 1). Coefficients of variation (CV) of method error were calculated to determine between-trial variability and the minimum detectable change (MDC) was calculated to indicate the difference in scores required to show a true change. This analysis was repeated for averages of the first three walks for each subject at each session. ICCs were found to be high (>0.86) for all gait parameters using both 10 and three walks, indicating high test-retest reliability for these measures in people with AD with as few as three walks. Measures of support base and toe in/out angle, however, had higher CV, even with increased numbers of walks, suggesting that only large changes in these parameters can be detected. MDC values suggested that demonstration of real change in gait measures is feasible in this population.

Longitudinal changes in knee joint biomechanics during level walking following anterior cruciate ligament reconstruction surgery

Following anterior cruciate ligament reconstruction (ACL) patients have altered movement patterns in the reconstructed knee during walking. There is limited information about these alterations over an extended period of time. This study was designed to present a longitudinal analysis of gait patterns following ACL reconstruction surgery. Assessments of level walking were undertaken in 16 participants at a mean 10 months (initial assessment) and again at 3 years (follow-up assessment) after ACL reconstruction surgery. Kinematic and kinetic variables were analysed using a two factor (time, limb) repeated measures ANOVA. Kinematic data showed that patients were able to achieve greater extension about the reconstructed knee at follow-up than at initial assessment. The reconstructed knee was significantly less internally rotated than the contralateral knee at the initial assessment but not at follow-up. Kinetic data showed a significant increase in the external knee extension moment for the reconstructed limb over time. There were also significant increases in the external knee adduction moment for both limbs at the follow-up assessment. The external knee adduction moment was however smaller in the reconstructed knee than the contralateral knee at both assessments. The results indicate that gait variables do change over time and that measurement at a single time point may not reflect the long term outcome of ACL reconstruction surgery. The changes were however small and may not be clinically relevant. However, the consistently reduced external knee adduction moment seen about the reconstructed knee in this study may suggest that factors other than joint moments influence degenerative change over time.

Rhythmic auditory cueing to improve walking in patients with neurological conditions other than Parkinson's disease - what is the evidence?

Purpose: To investigate whether synchronising over-ground walking to rhythmic auditory cues improves temporal and spatial gait measures in adults with neurological clinical conditions other than Parkinson’s disease. Method: A search was performed in June 2011 using the computerised databases AGELINE, AMED, AMI, CINAHL, Current Contents, EMBASE, MEDLINE, PsycINFO and PUBMED, and extended using hand-searching of relevant journals and article reference lists. Methodological quality was independently assessed by two reviewers. A best evidence synthesis was applied to rate levels of evidence. Results: Fourteen studies, four of which were randomized controlled trials (RCTs), met the inclusion criteria. Patient groups included those with stroke (six studies); Huntington’s disease and spinal cord injury (two studies each); traumatic brain injury, dementia, multiple sclerosis and normal pressure hydrocephalus (one study each). The best evidence synthesis found moderate evidence of improved velocity and stride length of people with stroke following gait training with rhythmic music. Insufficient evidence was found for other included neurological disorders due to low study numbers and poor methodological quality of some studies. Conclusion: Synchronising walking to rhythmic auditory cues can result in short-term improvement in gait measures of people with stroke. Further high quality studies are needed before recommendations for clinical practice can be made. Implications for Rehabilitation Gait training using synchronisation of walking to rhythmic auditory cues may improve stride length and velocity in people with stroke. Further research is needed before recommendations regarding the use of rhythmic auditory cueing for patients with neurological disorders other than Parkinson’s disease can be made.

Quantitative gait analysis after medial unicompartmental knee arthroplasty for Osteoarthritis.

This study characterized the footstep pattern and knee kinematics during walking in 12 patients who had undergone unicompartmental knee arthroplasty for unilateral medial compartment osteoarthritis. Patients had all achieved a successful recovery and were tested at least 1 year after surgery. Gait analysis was conducted during self-selected comfortable and fast walking conditions using a 3-dimensional motion analysis system and electronic walkway. Results showed that patients were able to increase their walking speed by 28% by increasing both stride length and cadence. All but one patient showed a biphasic pattern of flexion-extension motion about the treated knee. In 8 of 12 patients, significant increases in knee flexion were seen in the treated limb compared with the contralateral limb, the cause and ramifications of which are yet to be determined.

Music and metronome cues produce different effects on gait spatiotemporal measures but not gait variability in healthy older adults.

Rhythmic auditory cues including music and metronome beats have been used, sometimes interchangeably, to improve disordered gait arising from a range of clinical conditions. There has been limited investigation into whether there are optimal cue types. Different cue types have produced inconsistent effects across groups which differed in both age and clinical condition. The possible effect of normal ageing on response to different cue types has not been reported for gait. The aim of this study was to determine the effects of both rhythmic music and metronome cues on gait spatiotemporal measures (including variability) in healthy older people. Twelve women and seven men (>65 years) walked on an instrumented walkway at comfortable pace and then in time to each of rhythmic music and metronome cues at comfortable pace stepping frequency. Music but not metronome cues produced a significant increase in group mean gait velocity of 4.6 cm/s, due mostly to a significant increase in group mean stride length of 3.1cm. Both cue types produced a significant but small increase in cadence of 1 step/min. Mean spatio-temporal variability was low at baseline and did not increase with either cue type suggesting cues did not disrupt gait timing. Study findings suggest music and metronome cues may not be used interchangeably and cue type as well as frequency should be considered when evaluating effects of rhythmic auditory cueing on gait. Further work is required to determine whether optimal cue types and frequencies to improve walking in different clinical groups can be identified.

Physiological Falls Risk Assessment in Older People with Alzheimer’s Disease

Background: Falls are common in people with Alzheimer’s disease (AD). There is some evidence that deficits in vision, peripheral sensation, strength, reaction time and balance may be partly responsible for this increased risk. Aims: To determine the feasibility and test-retest reliability of a physiological test battery designed to assess falls risk [the Physiological Profile Assessment (PPA)] in people with AD, and to compare their PPA scores to age- and sex-matched controls. Methods: Twenty-one community-dwelling people with probable, mild to moderate AD aged 63–91 years, and 21 age- and sex-matched controls underwent the PPA tests and the Mini-Mental State Examination. All tests were then repeated in the AD group to determine test-retest reliability. Results: Most of the PPA tests could be successfully administered to participants with AD. The AD group had a significantly higher overall falls risk score (t40 = –2.41, p < 0.02), slower hand (t40 = –4.86, p < 0.01) and foot reaction time (t40 = –2.26, p < 0.05) and worse coordinated stability (t40 = –2.40, p < 0.05) than the controls. Conclusion: Physiological falls risk assessment is feasible in older people with mild to moderate AD. Older people with AD demonstrate significant impairments in several physiological domains, particularly reaction time, compared to controls.

A longitudinal study of measures of walking in people with Alzheimer's Disease.

Longitudinal gait measures may be used to provide baseline data for intervention studies. This has not previously been reported in people with Alzheimers Disease. In this study measures of walking and their variability were recorded for 19 people with Alzheimers Disease on two occasions 1 year apart. Matched controls were measured once. Variability was calculated using the coefficient of variation (CV). Effect size was calculated using Cohens d. Gait was slower and more variable in the Alzheimers Disease group compared to controls. Over 1 year there was a decrease in velocity (initial=103.9cm/s, follow-up=95.1cm/s; p<0.05, d=0.4) and stride length (initial=119.6cm, follow-up=112.5cm; p<0.05, d=0.34) and an increase in double support (initial=24.2%, follow-up=30.1%; p<0.05, d=0.99) and stride length variability (initial CV=3.5%, follow-up CV=4.6%; p<0.05, d=0.65). These changes occurred in mild as well as more severe Alzheimers Disease. Future research should focus on reducing this decline early in the course of the disease in order to maintain physical independence for as long as possible.

Three dimensional motion analysis of within and between day repeatability of tibial rotation during pivoting.

Activities that involve a change in direction apply a high rotational load to the knee joint. Biomechanical analysis of such activities may be useful for determining mechanisms that underlie knee injury and the success of ligament reconstruction surgery. However, the reliability of the measurement of tibial rotation remains unclear. The purpose of this study was to determine the reliability of tibial rotation measurements during a pivoting task, both between testing sessions conducted on the same day and between those made one week apart. Three-dimensional motion analysis was used to measure peak internal tibial rotation and rotational excursion during a stair descent and pivoting task in eleven healthy subjects (six female, five males). Intraclass correlation coefficients (ICC (3, 1)) and typical error analyses were used to examine within and between day reliability. Tibial rotational excursion had excellent reliability for within day (ICC=0.82) and between day sessions (ICC=0.76) whereas peak internal rotation had good reliability (within ICC=0.74; between ICC=0.68). Typical error was less than 2.4 degrees for within day measures and 2.9 degrees for between day measures. It was concluded that tibial rotation can be measured reliably during pivoting. Typical error values were less than the usual group differences in rotational excursion reported in the literature. The ability to reliably quantify tibial rotation during dynamic activities is important in determining the causes of persisting instability following anterior cruciate ligament reconstruction.