Gait symmetry and functional walking performance in hemiparetic patients prior to and after a 4-week rehabilitation programme

Gait & Posture

1993;

1: 166-l

71

Gait symmetry and functional walking performance in hemiparetic patients prior to and after a 4-week rehabilitation programme S

A Hesse

MD,

M T Jahnke

MD,

C Schreiner

MD,

K-H Mauritz

MD

Klinik Berlin, Department of Neurological Rehabilitation, Freie Universitlt Berlin, Germany

Summary Gait symmetry was examined in 40 hemiparetic stroke patients before and after a 4-week inpatient rehabilitation programme based on the neurodevelopmental technique (NDT) according to Bobath. Vertical ground reaction forces were measured with force plates, and symmetry ratios (affected versusnon-affected leg) were calculated for peak vertical ground reaction forces at heel strike (Fzl ) and toe-off (Fz2). loading and deloading rates and time to peak Fzl (tl ) and Fz2 (ti) in relation to the duration of the stance phase. In addition to these measurements conventional gait assessment was performed (maximal walking speed, endurance, stair climbing), and the motricity index was assessed prior and after the in-patient therapy programme. Although the training of gait symmetry functions is an integral part of the Bobath technique, there was no significant improvement in the gait symmetry parameters after 4-week’s training, with an amount of training sessions typical for rehabilitation hospitals in Germany and other countries. Endurance was also not increased, whereas other functional gait parameters (maximal speed, stair climbing velocity) and the motricity index showed significant improvement. The implications of these results for physiotherapy are discussed. Key words: Hemiplegia, gait symmetry,physiotherapy,neurodevelopmentaltechnique (Bobath concept)

Introduction

Twenty-five percent of all stroke survivors will never be able to ambulate independently, and in 50%, walking speed is still more or less reduced after 3 months’. For Germany, these numbers mean that almost 50 000 patients remain wheelchair-bound each year, and enormous costs are involved in their care. To improve the gait training in order to regain independent mobility is therefore an important issue in the neurological rehabilitation of stroke patients. Different treatment designs are applied including a functionally oriented ‘traditional’ approach, and various treatment techniques based on neurophysiological models such as the Bobath (NDT)?.), Brunnstroem4, Roods, and PNF concept6. Received: 3 January 1993 Accepted 26 July 1993 Correspondence and reprint requests to:

Kladower

Damm

StefanHesse

223, 14089 Berlin. Germany

0 1993 Butterworth-Heinemann 09666362/93/03 166-06

Ltd

MD.

Klinik Berlin,

Nowadays, the time-consuming and cost-intensive Bobath neurodevelopmental technique (NDT) is most widely applied in Germany. Despite theoretical and practical differences, the NDT technique so far has not been demonstrated to be superior to the others in controlled studies’-r2. Physiotherapists trained in Bobath often argue against these results because only functional criteria such as activities of daily living (ADL) were applied. These parameters, however, would not reflect the aspired qualitative improvement of movement. We therefore decided to validate the NDT technique on the basis of its own demands. One of its principal goals is the restoration of the physiological gait pattern, in particular the gait symmetryj. For normal subjects, symmetry of kinematic’3.t4, kineticISlE and to some degree EMG data 19JOcouldbe documented. On the other hand, asymmetry of the hemiparetic gait is well established for kinemati+** and (in single case studies) kinetic*3J4data. The Bobath method requires reflex inhibitory movement patterns to be invoked in order to normalize muscle

Hesse et al.: Gait symmetry in hemiparetics

tone. During gait training, symmetric weight acceptance and push-off are strictly controlled and a ‘non-use’ of the paretic limb is avoided. Since no quantitative studies exist we tried to evaluate whether physiotherapy with the Bobath technique was able to improve gait symmetry in stroke patients. We evaluated gait symmetry on the basis of differences of the vertical ground reaction forces (GRF)?5 between the affected and non-affected leg. Furthermore, clinical parameters measuring functional gait capability were studied: the time needed to walk a 10-m distance, and the endurance of walking and stair climbing.

167

WNI

Verttcal Force I

1 iF,1

Methods Subjects

The study was performed on 40 ambulatory patients with a spastic hemiparesis, 25 male and 15 female. Mean age was 54.9 years, ranging from 15 to 74 years. Seventeen of the patients suffered from a hemiparesis on the right-side and 23 on the left side. Aetiology in all cases was an ischaemia in the territory of the middle cerebral artery (MCA) or anterior cerebral artery (ACA). Mean time interval since stroke onset was 63 days (45-128). Nineteen patients complained of impaired proprioception in the affected leg. All patients gave informed consent and met the following criteria:

(1) age under 75 years; (2) ability to walk a 10-m distance in less than 15 s (3) (4) (5)

(6)

unaided (gait velocity > 0.67 m-r s-r); no additional neurological and/or orthopaedic deficits impairing ambulation; no heart failure or less than grade 2 New York Heart Associationz6. no severe cognitive’or communication impairment which might hamper the understanding of therapists’ instructions; 5 weeks minimum time interval since stroke onset with an upper limit of 1 year.

Patients were investigated prior and after a 4-week inpatient rehabilitation. They received 45 min of physiotherapy based on the Bobath concept on a regular basis (five times per week). The therapy was performed by experienced therapists with additional qualification in the Bobath technique. Any change in therapists was avoided as far as possible and the qualification of the physical therapists was quite comparable. None of them was informed which patients were included in the study. Additionally, patients were instructed in a self-administered training programme for at least 30 min daily. Occupational therapy, speech therapy, and neuropsychological training were administered according to individual needs.

Figure 1. Force variables analyzed in the vertical plane.

Data acquisition

Assessment of vertical ground reaction forces Vertical ground reaction forces were measured for each leg using the Kistler gait symmetry system (Kistler AG, Winterthur). The system consists of a segmented platform walkway (8 x 1.2 m) with two embedded force plates (60 x 40 cm). Once the patient’s stride length and pattern had been established after several trials, the orientation of the force plates (either transverse or longitudinal) was adjusted so that double step measurements could be made (sampling rate 200 Hz). If the stride was not long enough to hit both plates, single step measurements were made. Patients walked barefoot at their preferred speed. Five single or double step measurements were recorded and checked for reproducibility. Measurements were repeated as necessary. Mean curves were then plotted and displayed along with five measured parameters for each leg (Figure l), namely foot-floor contact time (stance), peak vertical ground reaction forces at heel strike (Fzl) and toe off (Fz2), and the loading and deloading rates (LR, DLR) from zero intercept to 80% of Fzl and Fz2 respectively. As described by Carl&i and co-workers?-‘, in some patients the normal m-shaped curve was replaced either by a plateau with only minor oscillations, or by a pyramid-shaped curve with one prominent ,crest. In the latter case, Fzl and Fz2 were supposed as equal, and in case of a plateau the peaks were assumed at the edges. The raw force data were divided by body weight to get normalized values (Fzl%, Fz2%). The temporal occurrence (t 1, 12) of Fzl and Fz2 as percentage of the stance duration was estimated. Asymmetry in these parameters between the affected and nonaffected leg was assessed by the ratio x-affected/ x - non-affected leg. The vertical GRF was chosen as an assessment tool on account of its minimal intraindividual variability?j, high accuracy of measurement, and simple applicabilityz5.z7. Further, in normal subjects the vertial GRF showed a

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Gait & Posture 1993; 1: No 3

high degree of symmetry compared components17.

to the horizontal

Assessment of functional status The following tasks were performed by the subjects: 10 m walking on level ground at his/her maximum gait velocity; walking endurance (self-adopted speed, limit 600 m); stair climbing (self-adopted speed, with or without the hand-rail, limit = 90 steps or five flights, height of one step 16 cm). During the assessment, patients wore their preferred shoes (Blucher or Bal style), no aids or ortheses were allowed. They were instructed to walk or climb at their preferred speed (except 10-m walking test), and to stop at any moment if they felt unable to continue. The maximum uninterrupted gait distance, number of steps, and the required time were recorded. In addition, scores of the motricity index of the paretic upper and lower extremity (O-100 points) were documentedzs. For statistical analysis the non-parametric Wilcoxon test was used. As a first step, differences between the affected and non-affected leg were calculated. To assess improvement of gait, symmetry quotients (affected versus non-affected leg) were compared before and after therapy. Since seven parameters of the vertical GRF and another seven describing the functional status were investigated, a corrected alpha value of 0.007 was chosen for each single comparison (assuming independency of the individual tests). The statistical software package SYSTAT (Systat Incorporation, 1988) was applied.

Results Parameters prior to therapy

Stance duration was significantly shorter on the affected side. Significant differences could also be documented for the Fz2%, deloading rates, and t2 values, illustrating a diminished push-off for the paretic leg. The tl value reflected a later occurrence of the first crest for the affected leg; Fz 1% and loading rates, however, did not differ significantly. There was even a tendency for the Fzl % to be larger on the diseased side (Table 1; Figure 2 a,b). Gait symmetry before and after therapy

Surprisingly, the symmetry ratios did not change significantly after 4 weeks of therapy (Table 2). Only the t2 value tended to improve. Therefore it can be concluded that gait symmetry did not markedly improve in this study group. Nevertheless improvement in individual cases could be seen. No significant interaction of the treatment effect with sensory impairment and/or age could be documented on the basis of the corrected alpha value of 0.007.

Table 1. Vertical ground reaction force parameters of the affected and non-affected leg before therapy

Stance (s) FzI % (%BW) LR (kN -1 s-1) fl (%stance) FzI% (%BW) DLR (kN-’ s-‘) f2 (%stance)

Affected

Non-affected

leg

leg

0.90 l 0.21 102.2 f 10.1 5.0 f 1.3 33.0 f 9.2 101.7 f 10.6 5.6 f 1.3 68.1 f 9.4

1 .oo f 0.31 101.3 f 5.0 5.4 l 1.4 28.1 f 8.4 106.7 f 8.5 4.5 f 1.4 73.5 *.6.3

P 0.000’ 0.021 0.230 0.009 0.004’ 0.001 0.000’

l

Means f SD;stance, stance duration; Fzl, 2%, peak vertical force in the loading phase and at push-off normalized by body weight; LR, DLR, loading and deloading rates in the time from 0 to 80% of Fzl res. 152; fl, 2, temporal occurrence of Fzl and Fz2 normalized by stance duration; ‘affected leg value significantly different from nonaffected leg value (P < 0.007).

Functional parameters before and after therapy

The functional status of the patients improved only partially. They walked and climbed quicker, but their endurance (ground level walking and stair climbing) remained virtually unchanged. The motor strength of the lower and upper affected limbs measured with the help of the motricity indexZS increased markedly (Table 3).

Discussion The selected gait parameters showed significant differences between the affected and non-affected sides prior to therapy. In accordance with other reports, a shorter stance duratiotP2, and a diminished push-off for the paretic leg24 could be documented. Reduced weight acceptance was only insignificantly expressed in a delayed occurrence of Fzl (tl value). This could be explained by a prolonged double support time when body weight was shifted from the non-paretic to the paretic leg22. No differences were found for the loading rate and Fzl%, which was also shown by Carlsiiii et a1.23.There was a tendency for Fzl% to be larger on the affected side. This may be interpreted as a sign of an uncontrolled loading phase. Another explanation is that the parameters of weight acceptance are partly determined by the almost normal momentum generated by the non-affected leg in its terminal stance phase. Since significant differences for the parameters reflecting weight acceptance could not be shown, the Bobath concept of an asymmetric weight take-over could not be verified for this group of patients. After therapy the symmetry indices did not change significantly for all patients. Only the t2 value almost reached the corrected significance level. With a more relaxed alpha level of 0.05, only t2 would have been significant. Thus the restoration of gait symmetry as one of the main goals of the Bobath concept could not be documented in this group of patients. The gait symmetry did not improve despite an increase in the average gait

Hesse et al.: Gait symmetry in hemiparetics

169

Patient 29, m, 59y, 75kg Hemiparesis right

Patient 17, m, 33y, 88kg Hemiparesis left

/

1..

i.

me _______~_i__~---________ 1

stancs[s] Fzl [KBW] FzZ[KBW] tl [SCstrncr] t?[Xstrnce] LR[kN/s] DLR[kNls]

al

naf

0.87 101 103 20 64 5.0 4.0

0.95 100 104 15 78 6.3 6.4

~._~-Bvi

stanco[s] Frl[%BW] FzP[%Bw] 11 [%strnce] 12[%SttmCe] LR[kN/s] DLR[kN/s]

a

__

t 1

at

naf

0.90 115 110 27 66 4.5 3.0

1.09 101 105 26 78 3.7 4.3

b

Figure 2. Representative vertical force diagrams of the affected and non-affected lower limbs in patient 17 and in patient 29. Note a shorter stance duration, a diminished deioading-rate and an earlier occurrence of Fz2 for the affected leg in both cases. The loading-rates, however, were inconsistent.

Table 2. Gait symmetry

before and after therapy

Before stance-R Fzl-R LR-R tl-R Fzl-R DLR-R t2-R

0.92 1.01 0.95 1.27 0.96 0.90 0.93

After * f f + f f f

0.09 0.11 0.31 0.63 0.11 0.18 0.12

0.93 1.03 1.00 1.19 0.95 0.92 0.97

P f f * Ik f * *

0.06 0.08 0.32 0.59 0.06 0.16 0.11

0.44 0.23 0.16 0.10 0.12 0.20 0.01

Means f SD; Ratios of the vertical ground reaction force parameters, x-affected versus x-non-affected leg.

Table 3. Functional

parameters

before and after therapy After

Before t/lOm (s) Dis (m) Vet-Dis (m/min) Steps (n) Vel-Steps (nlmin) MIF MIH

9.9 496 57.1 77.9 48.5 81.6 67.3

f 4.1 f 171 f 16.7 f 21.9 f 17.9 f 16.9 f 27.6

9.0 526 60.8 79.2 60.3 87.5 76.6

P f f f k rt f f

4.3 139 15.3 18.5 24.3 13.8 23.6

0.000’ 0.014 0.010 0.510 0.000’ 0.000’ 0.001.

Means k SD; r/lOm, time for 10-m walking distance; Dis, maximum ground level walking distance; Vel-Dis, average velocity during ground level walking; Steps = number of climbed steps; VelSteps, average velocity during step cltmbing; MIF, MIH, motricity index of the lower and upper paretic limb; ‘post-traming value significantly different from pretraining value (P < 0.007).

velocity as shown by the t/IO-m value. Although vertical force parameters of both legs are linearly dependent on gait velocity, absolute differences between corresponding parameters of the affected and non-affected leg are virtually independent of the walking speed both in hemiparetic patientsz9 and normal personsjO. Therefore the ratios used in our study should tend to get smaller with increasing gait velocity for purely mathematical reasons, which was not the case. These results correspond with several studies which failed to demonstrate the superiority of the Bobath concept for improvement of activities of daily living’-12. Objections to these studies are based on the fact that only functional criteria such as ADL were applied, which did not reflect qualitative improvement of the gait pattern. For that reason the gait symmetry was chosen for assessment of the gait training within the Bobath concept. The vertical force trajectories were particularly suitable as they reflect the weight acceptance and push-off. both emphasized by the Bobath concept”. The patient population of this study was relatively homogeneous, a number of 40 patients seemed sufficient to detect relevant therapeutic effects. Change of therapists was avoided and their qualifications were comparable. Confounding effects of spontaneous recovery cannot be excluded, but with a mean referral time of 63 days after stroke most of the spontaneous recovery should have occurred’ and mainly the net therapeutic erect was investigated.

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A long time interval between the stroke onset and admission to the rehabilitation unit, which might have prevented a better result, is an outcome of German health politics. Before admission patients have to fulfil several criteria including mobility and independence in the basic activities of daily living. More extensive therapy might lead to a better result, but it was this study’s intention to investigate routine conditions and the rather low number of therapeutic sessions per week is typical for rehabilitation units in Germany. Due to economic constraints more single training sessions are not realistic. A therapeutic period of more than 4 weeks is usually not funded by German health insurance companies for these kinds of patients. Another explanation for the non-improvement of gait symmetry might lie in the therapy itself. During a Bobath session, tone inhibiting manoeuvres and advanced postural reactions are applied during sitting and standing to normalize the muscle tone2,3. Practising gait, however, is only a minor part of the therapeutic session and the patient is strictly encouraged to walk in a slow controlled way. Patients are often not able to reproduce these preparatory patterns outside the therapy due to cognitive impairment or pronounced spasticity. The gait training is therefore a secondary issue within this technique. However, neuronal mechanisms of learning complex motor skills may require substantial repetitive training31. Assumed insufficiency of gait practice may be supported by the functional gait level of patients. Although they walked and climbed faster, the endurance of ground level walking and stair qlimbing did not change. With more practice a better’ endurance level would be achieved. Whether or not the documented increase in gait velocity and motor strength can be related to Bobath therapy remains a matter of debate. Strengthening of paretic muscles is not within the scope of the NDT technique but presumably regarded as a side-effect of the training programme. Parallel improvement of the gait velocity and muscle strength was demonstrated in a study of Bohannon and Andrews, who also claimed that walking speed was little influenced by the muscle tone32. Further conclusions for the gait training of hemiparetic patients in neurological rehabilitation should be drawn with great caution. First, the study did not compare different therapeutic concepts, due to the fact that therapists of our units were exclusively trained in the NDT technique, which they thoroughly support. Second, the total amount of therapy was rather limited due to the situation of the health care system in Germany. Third, the dependent variables used in this study cover only a segment within the possible spectrum of improvement. Nevertheless, the symmetry parameters were chosen because they reflect the intended goal of the NDT technique. Thus, as long as there is no definite proof of the superiority of the NDT technique, neither in this nor in other studies’-‘2, the authors advocate a more flexible and competitive therapeutic regime.

Acknowledgements

Part of the study was supported by a grant to the Klinik Berlin from the Bundesversicherungsanstalt fur Angestellte.

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