- Email: [email protected]
A gait analysis system in clinical practice
A GAIT ANALYSIS G. Gifford
SYSTEM IN CLINICAL
PRACTICE
and J. Hughes
ABSTRACT A gait analysis system using a transduced walkway, monitored by microcomputer to measure the time and distance factors of gait, has been in regular clinical use for over two Keywords: Locomotor
and a half years. The results are easy to understand and haue provided objective data which has been found useful in a number of clinical situations. Some of the ways in which the system has been used are described.
system, gait analysis, computer
Recent years have seen a growth of interest in gait analysis but despite this, few systems are in regular clinical use, most being confined to academic or hospital research departments. One reason for this may be related to the clinician’s desire for a diagnostic tool which gait analysis has so far not proved to be. This should not be taken as an indictment of gait analysis, however, as it can be a valuable tool, both in assessment and in monitoring progress and can also be a helpful form of feedback to encourage patients. Other problems with routine gait analysis include the need for highly qualified operators and the time taken to analyse the data and produce results. For gait analysis to be acceptable to clinicians working in a busy hospital, the system must be simple to use and the results easy to understand. Ideally, the apparatus should be operable by anyone, have a fast patient turn around time (no more than five minutes), produce a hard copy output, and provide information which can be readily understood. A system which meets these requirements is in regular clinical use at Northwick Park Hospital, Harrow, and at the Canadian Red Cross Memorial Hospital at Taplow. A review of this system is given in this paper. Comprehensive gait analysis may involve the measurement and recording of many parameters, including:- time and position of foot contacts; - force transmission from limb to floor; - joint movement in one or more planes; - limb movement in two or three planes; - muscular activity; - metabolic cost. To measure all of these simultaneously would require an extremely expensive system, and would burden the patient with multiple probes and sensors. It would also take a considerable time to analyse, and would produce a large volume of results. As a consequence even the most sophisticated of the research-based systems only attempt to record a few of these variables at one time. Northwick Park Hospital, Watford Road, Harrow, Middlesex HA1 SUJ and Canadian Red Cross Memorial Hospital, Taplow, Maidenhead, Berks SL6 OHN.
0 1983 Butterworth & Co (Publishers) 0141-5425/83/040297-05 803.00
When considering systems which fulfil clinical needs, it becomes necessary to reduce the task to recording only a small number of variables, which need to be chosen with a particular patient population in mind. The system used at Harrow and Taplow measures the time and distance factors of gait. These variables were chosen because the patient population consisted mainly of adults undergoing total hip replacement (THR) and children with juvenile chrome arthritis (JCA). With both of these groups, clinical improvement can be signified by progress towards a symmetrical gait and an increase in velocity. The temporal and distance factors (contact time, swing time, stride length, stride time, velocity, cadence, and double support time) provide a gross assessment of a patient’s ability to walk, which can then be compared with previous results. This system thus provides an effective monitor of progress or deterioration over a period of time, and can be used for comparison with a pre-treatment condition. The portable system used consists of a transduced walkway 3 metres long which is monitored by a microcomputer (Figure 1). Contact is made with the walkway by metallic adhesive tape which is stuck on to the soles of the shoes. The patient traverses the walkway, using walking aids if necessary, while a print-out is produced by the microcomputer on a line printer. Before the system was used for patient studies, normal baselines were established by recording the gait of one hundred and fifty normals, aged from five to seventy-nine years. A condensed summary of this normal data is presented in Table I. The data is presented in full in a thesis by G. Gifford’. Measurement accuracy for all distance-related parameters is f 0.0126M and for all the time-related parameters better than 8.0 X la? s. Technical details of the walkway are described elsewhere’. It is currently being developed and further simplified in order to extend its use. The walkway has now been in use for two and a half years. It was first used to monitor progress in osteo-arthritic adults who were undergoingtotal hip replacement (THR). Since then it has been applied principally to monitor gait changes in
Ltd J. Biomed.
Eng. 1983, Vol. 5, October
297
Gait analysis: G. Cifford and J. Hughes
MONITORING IMPROVEMENT OF HIP ARTHROPLASTY PATIENTS Monitoring the progress of a patient before and after THR is demonstrated in Figures 2, 3 and 4. These show three sequential assessments of a patient (Pl) taken pre-operatively, and eleven days and five months after operation. From the preoperative print-out (Figure 2) it can be seen that the velocity was extremely low at 17 cm/s (normal velocity 121 cm/s). This was the result of both a limited stride length and a reduced cadence.
Figure 1 The gait analysis system at Northwick Park Hospital
Clinical examination suggests that the former was due to ankylosis of the affected hip, and the latter to the excessive energy expenditure and pain involved in trying to move the diseased joint. The considerable asymmetry of contact time which existed between the left and right feet was probably due to the patient’s efforts to minimise wei htbearing on the affected left side (antalgic gait7.
set up in the gymnasium
The ‘mean time factor’ graph is a graphical reprenm*
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Assessment
before
left total hip replacement
children with juvenile chronic arthritis (JCA). Patients undergoing active treatment regimes are sent for gait analysis at regular intervals before, during and after treatment. In this way, the progress of the patient over an extended period is recorded, and the long term effects of treatment may be quantified. Some examples of the ways in which the walkway has been used are given below. Table 1 Mean values of gait parameters in parenthesis.
recorded
for normal
niiw
DIS,TyE
% yy’
Mean
sample
age
Kg
5-9
13
6.77 (1.17)
24.92 (5.65)
1.25 (0.09)
5.74 (2.63)
0.53 (0.08)
lo-19
54
13.04 (1.77)
44.3 1 (10.57)
1.55 (0.11)
5.56 (4.43)
20-29
27
24.00 (273)
64.26 (11.10)
1.71 (0.09)
30-39
20
34.00 (2.66)
59.00 (10.60)
40-49
9
43.67 (2.55)
63.67 (10.25)
53.69
60.62
50-59
13
(3.25)
(5.64)
63.90 60-69
10
(3.35)
64.30 (7.76)
7&79
11
(2.87)
60.55 (4.06)
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*
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-0 .
Figure 3 Assessment replacement aged 5-79
. . . . . . . ..‘~
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8
Size of
. .
;*““““““““‘;‘“”
Mean stride time
Age range
...“.“.”
5(YE,I
Mean swing time
Mean height m
75.36
.
““““‘~
Contact time Mean asymmetry as contact % of stride time time S
MealI weight
mm,
mm0
::h y.v,
0
0
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*o
. . . . . . ;““...*+*wy......+
0
.
-0
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11 days after left total hip
years of age. Standard
deviations
are shown
8
Stride ler@h a~ % of height
Velocity m C’
Cadence steps miri’
Foot placement asymm etry %
0.51 (0.08)
1.04 (0.12)
8219 (10.40)
1.08 (0.15)
117.69 (14.53)
6.31 (5.99)
0.57 (0.07)
0.49 (0.07)
1.06 (0.10)
85.53 (7.66)
1.30 (0.15)
115.19 (1209)
3.59 (3.61)
4.69 (3.95)
0.65 (0.09)
0.46 (0.05)
1.12 (0.10)
81.10 (8.42)
1.27 (0.18)
108.52 (9.76)
5.04 (4.82)
1.70 (0.10)
4.28 (4.08)
0.60 (0.08)
0.49 (0.07)
1.09 (0.08)
83.49 (10.06)
1.35 (0.27)
111.15 (8.07)
6.00 (4.21)
1.70 (0.07)
5.54 (3.36)
0.62 (0.10)
0.51 (0.09)
1.12 (0.10)
84.56 (9.54)
1.31 (0.04)
107.78 (10.89)
(2.85)
1.67
7.82
(0.10)
(5.02)
0.59 (0.09)
0.54 (0.10)
1.13 (0.14)
81.34 (9.54)
1.27 (0.30)
107.77 (13.11)
3.23 (4.04)
1.60 (0.12)
5.42 (4.43)
0.66 (0.09)
0.44 (0.07)
1.11 (0.13)
78.51 (7.69)
1.16 (0.18)
109.60 (11.89)
5.80 (3.82)
1.64 (0.07)
6.19 (2.94)
0.60 (0.05)
0.49 (0.04)
1.09 (0.05)
72.23 (3.89)
1.19 (0.09)
110.09 (5.13)
5.09 (2.43)
298 J. Biomed. Eng. 1983, Vol. 5, October
2.89
Gait analysb: G. Gifford and J. Hughes
cosmetic symmetry of the gait pattern had returned and the stride length had increased to within normal limits. The patient’s velocity was still quite slow, and he still required the extra stability provided by the stick, but the patient now had a symmetrical painless gait, indicating a good operative result. 111
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nc,.x mm
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MONITORING GAIT CHANGES AFTER SOFT TISSUE RELEASE (STR) AT THE HIP
*
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Figure 4 Assessment 5 months after left total hip replacement
sensation of the contact time and swing time values, and serves to emphasise any gross asymmetry of the temporal aspects of the gait. The ‘mean distance factor’ graph shows the relative positions of the left and right heel contact. It can be seen that the longer step was taken with the left foot. The RPC (relative position of contact) value of 100/25 is a quantitative measure of this step length asymmetry and shows that the right step length was one half of that required for symmetrical gait (normal value 100/50). In Fz&re 3, the assessment taken eleven days post-operatively, some immediate improvements can be seen. The velocity had increased almost four-fold, as a consequence of the great improvements in both stride length and cadence. The improvement of step length symmetry can be seen in the ‘mean distance factor’ graph, and the positioning of the aids in this graph suggests that they were being used more for stability than for protection. The asymmetry of contact time between left and right foot was still present but this may have been due to the patient’s unwillingness to overstress the new joint. The final assessment of patient Pl taken five months after operation (Figure 4) shows that the
Patient 2 was a thirteen-year-old female with an inflammatory mono-arthritis of the right hip. She developed a painful right hip which, despite active physiotherapy and night traction, became rapidly stiff and painful. The assessments presented were carried out pre-operatively, and two weeks and six weeks post-operatively. For reasons of space, full print-outs are omitted, but the trends for the five most important variables are presented graphically in Figure 5. Improvement is signified by upward trends in the top three graphs and downward trends in the bottom two. It can be seen that four of the variables (velocity, cadence, stride length and foot placement asymmetry) had regressed at the second assessment (two weeks ost-operative), but by the third assessment Qsix weeks post-operative) they had recovered to their former level. Contact time asymmetry showed a remarkable improvement from 21% pre-operatively to 1% two weeks post-operatively and 2% six weeks post-operatively, both post-operative values being within normal limits for this variable. Although the improvement was evident clinically, numerical validation of this can be most useful, particularly if it is required to compare the results of different forms of treatment. MONITORING GAIT CHANGES AFTER INTRA-ARTICULAR STERIOD INJECTIONS Patient 3 was a female aged seven who had systemic onset of JCA at the age of one and a half years. All the joints had been causing problems, with slight limitation of movement of both hips. The knees were painful and swollen, although the 140-I
oJ1 a-
- o-l,-, 2
1
3
Assessment
Assessment
b S.
3 2
3%
Assessment
oJ,_, 1
2
3
Assessment
Assessment
Figure 5 Graphical representation of information from print-outs of assessments before, two weeks after and six weeks after surgery to release the soft tissue at the hip
1 Assessment
Assessment
s
Assessment
2 Assessment
Assessment
Figure 6 Graphical representation of information from print-outs of assessments before and one week after injections of steroid into both knees
J. Biomed. Eng. 1983, Vol. 5, October
299
Gait analysk
%
G. Giffoord and J. Hughes
Assessment
z
Assessment
The plaster was applied with the knee in as corrected a position as possible, and worn for a period of four days. Pre-treatment assessment (assessment 1) showed a considerable degree of asymmetry in both contact time and foot placement. The posttreatment assessment taken six days later (assessment 2) showed contact time asymmetry to have been reduced to within normal limits, and a significant improvement was seen in foot placement symmetry. Velocity, cadence and stride length also showed improvement.
Assessment
Figure 7 Graphical representation of information from print-outs of assessments before and 6 days after application of a serial plaster for contracture of the left knee
Clinically the im rovement in the range of movement was small P5’) and it is probable that the re-education which had clearly taken place would have been overlooked without objective assessment figures.
range of movement was near normal, with only a slight limitation of flexion on the right. A bilateral intra-articular steriod injection was performed.
TESTING THE IMMEDIATE PHYSIOTHERAPY
Assessment
Assessment
Graphs of data taken from her print-outs can be seen in Figure 6. In the first assessment (preinjection), all gait parameters except cadence were below normal for her age. In the second assessment (one week post-injection) there was a marked improvement in the asymmetry parameters but little change in velocity, cadence or stride length. The reasons for this are not clear, but it is probable that the injections relieved the pain, allowing a return to symmetry, but the poor gait remained, due to limitation of movement of the hips.
TESTING
THE EFFECT
OF SERIAL
PLASTERING
Fipre 7 shows the effect on gait of serial plastering on a four-year-old male with mono-articular arthritis of the left knee. He had a 30’ fixed flexion deformity with little movement in either direction. Examination under anaesthetic showed some movement to be possible and serial plastering to improve extension was suggested.
EFFECT
OF
Patient 5 was a six-year-old female with a recent onset of juvenile chronic arthritis involing hips, knees and ankles. Routine physiotherapy for patients with JCA who are in hospital involves twice-daily exercise sessions both in and out of the pool, in which all joints are put through a full range of movement. The children suffer from some degree of morning stiffness, and the first physiotherapy session of the day helps to relieve this. The two assessments were carried out before and after the mornin physiotherapy session, which lasted one hour ksee Figure 8). The first assessment shotied excessive foot placement asymmetry (24%) which decreased to within normal limits (6%) in the second assessment. The small increase in contact time asymmetry from 4% to 10% was not considered a significant deterioration, as it is close to normal limits for her age group. Thus the beneficial effect of physiotherapy can be demonstrated over a short period of time.
80
6o 40 20 1 OIp
Assessment
*
Assessment
1
2 Assessment
s $ I 3 .: P E 8
Assessment
Assessment
Figure 8 Graphical representation of information from print-outs of assessments before and after one hour of physiotherapy
300 J. Biomed. Eng. 1983, Vol. 5, October
60 50 40 u) 20 lo 0
Stick Crutches Frame Normal
Figure 9 Histogram to show comparative performance of patient using different walking aids. All measurements were taken on the same occasion. Normal data is presented for reference
Gait analysis: G. Cifford and J. Hughes
LONG-TERM MONITORING As mentioned in the introduction, records of gait analysis can be made routinely to monitor gait performance over a long period. The activity of the disease may fluctuate, and different therapies may affect walking ability. Provided these are taken into account when analysing results, accurate assessments of progress or deterioration can be made.
Figure 10 Graphical representation of a single patient’s assessments carried out over a two year period. Normal values are presented alongside with standard deviations in parentheses 1. represents an operation to correct the position of the left hip 2. represents the onset of deterioration
of the left knee
COMPARISON OF WALKING AIDS Assessment of correct walking aids is important, and needs constant review due to the condition of the weightbearing joints. For example, prolonged use of elbow crutches puts excessive strain on the shoulders. Gait analysis can provide help with this assessment, as several walks with different aids can single out the one which gives the most symmetrical gait. The types of walking aid most commonly used by these patients are sticks, elbow crutches and a wheeled high frame. Figure 9 shows the results of an assessment of one patient using all three types of aid compared to normal values for his age. This showed a marked improvement in velocity and stride length when using the high wheeled frame, combined with some improvement in both foot placement and contact time symmetry. Results from a number of such assessments have shown that in the majority of patients the most symmetrical gait is achieved when using the high wheeled frame, but this type of information needs to be considered together with the clinical assessment.
F@re 10 shows a graphic representation of one patient who has been assessed for more than two years. The first assessment shown was taken in January 1980 when th e patient was nine-years old. He had a rapid systematic onset of JCA at the age of five and had problems with many joints but the left hip became very stiff and he had an operation to correct the position of this hip in June 1980. The graph shows the change in his gait performance following surgery and provides an accurate record of his activity at each assessment. CONCLUSION Gait analysis by a microcomputer connected to a conductive walkway has been shown to provide useful objective data in a number of clinical situations. Its usefulness as a monitor of ait changes over short or long periods has been diemonstrated and it is envisaged that a system such as this would be of particular value to physiotherapists who, in general, lack objective data about their patients. The system is both quick and easy to use and the results are readily understandable and it is hoped, therefore, that systems such as this one will be used more widely in the clinical field in future. REFERENCES 1
2
Gifford, G. A microprocessor controlled system for measuring the temporal/distance factors of gait. A thesis submitted for the degree of Doctor of Philosophy of the Council for National Academic Awards School of Engineering and Science. The Polytechnic of Central London. August 1981. Gifford, G. and Hutton, W.C. A microprocessor controlled system for evaluating treatments for disabilities affecting the lower limb, J. Biomed. Engng. 1980, 2, 45
J. Biomed Eng. 1983,
Vol. 5,
October 301
SYSTEM IN CLINICAL
PRACTICE
and J. Hughes
ABSTRACT A gait analysis system using a transduced walkway, monitored by microcomputer to measure the time and distance factors of gait, has been in regular clinical use for over two Keywords: Locomotor
and a half years. The results are easy to understand and haue provided objective data which has been found useful in a number of clinical situations. Some of the ways in which the system has been used are described.
system, gait analysis, computer
Recent years have seen a growth of interest in gait analysis but despite this, few systems are in regular clinical use, most being confined to academic or hospital research departments. One reason for this may be related to the clinician’s desire for a diagnostic tool which gait analysis has so far not proved to be. This should not be taken as an indictment of gait analysis, however, as it can be a valuable tool, both in assessment and in monitoring progress and can also be a helpful form of feedback to encourage patients. Other problems with routine gait analysis include the need for highly qualified operators and the time taken to analyse the data and produce results. For gait analysis to be acceptable to clinicians working in a busy hospital, the system must be simple to use and the results easy to understand. Ideally, the apparatus should be operable by anyone, have a fast patient turn around time (no more than five minutes), produce a hard copy output, and provide information which can be readily understood. A system which meets these requirements is in regular clinical use at Northwick Park Hospital, Harrow, and at the Canadian Red Cross Memorial Hospital at Taplow. A review of this system is given in this paper. Comprehensive gait analysis may involve the measurement and recording of many parameters, including:- time and position of foot contacts; - force transmission from limb to floor; - joint movement in one or more planes; - limb movement in two or three planes; - muscular activity; - metabolic cost. To measure all of these simultaneously would require an extremely expensive system, and would burden the patient with multiple probes and sensors. It would also take a considerable time to analyse, and would produce a large volume of results. As a consequence even the most sophisticated of the research-based systems only attempt to record a few of these variables at one time. Northwick Park Hospital, Watford Road, Harrow, Middlesex HA1 SUJ and Canadian Red Cross Memorial Hospital, Taplow, Maidenhead, Berks SL6 OHN.
0 1983 Butterworth & Co (Publishers) 0141-5425/83/040297-05 803.00
When considering systems which fulfil clinical needs, it becomes necessary to reduce the task to recording only a small number of variables, which need to be chosen with a particular patient population in mind. The system used at Harrow and Taplow measures the time and distance factors of gait. These variables were chosen because the patient population consisted mainly of adults undergoing total hip replacement (THR) and children with juvenile chrome arthritis (JCA). With both of these groups, clinical improvement can be signified by progress towards a symmetrical gait and an increase in velocity. The temporal and distance factors (contact time, swing time, stride length, stride time, velocity, cadence, and double support time) provide a gross assessment of a patient’s ability to walk, which can then be compared with previous results. This system thus provides an effective monitor of progress or deterioration over a period of time, and can be used for comparison with a pre-treatment condition. The portable system used consists of a transduced walkway 3 metres long which is monitored by a microcomputer (Figure 1). Contact is made with the walkway by metallic adhesive tape which is stuck on to the soles of the shoes. The patient traverses the walkway, using walking aids if necessary, while a print-out is produced by the microcomputer on a line printer. Before the system was used for patient studies, normal baselines were established by recording the gait of one hundred and fifty normals, aged from five to seventy-nine years. A condensed summary of this normal data is presented in Table I. The data is presented in full in a thesis by G. Gifford’. Measurement accuracy for all distance-related parameters is f 0.0126M and for all the time-related parameters better than 8.0 X la? s. Technical details of the walkway are described elsewhere’. It is currently being developed and further simplified in order to extend its use. The walkway has now been in use for two and a half years. It was first used to monitor progress in osteo-arthritic adults who were undergoingtotal hip replacement (THR). Since then it has been applied principally to monitor gait changes in
Ltd J. Biomed.
Eng. 1983, Vol. 5, October
297
Gait analysis: G. Cifford and J. Hughes
MONITORING IMPROVEMENT OF HIP ARTHROPLASTY PATIENTS Monitoring the progress of a patient before and after THR is demonstrated in Figures 2, 3 and 4. These show three sequential assessments of a patient (Pl) taken pre-operatively, and eleven days and five months after operation. From the preoperative print-out (Figure 2) it can be seen that the velocity was extremely low at 17 cm/s (normal velocity 121 cm/s). This was the result of both a limited stride length and a reduced cadence.
Figure 1 The gait analysis system at Northwick Park Hospital
Clinical examination suggests that the former was due to ankylosis of the affected hip, and the latter to the excessive energy expenditure and pain involved in trying to move the diseased joint. The considerable asymmetry of contact time which existed between the left and right feet was probably due to the patient’s efforts to minimise wei htbearing on the affected left side (antalgic gait7.
set up in the gymnasium
The ‘mean time factor’ graph is a graphical reprenm*
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..........
2R !I”’
*w,.
. ...*
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rarvx
“E(Y llSl*rC
:::r
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‘;
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SNYE,” ;“““““”
Figure 2
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Assessment
before
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children with juvenile chronic arthritis (JCA). Patients undergoing active treatment regimes are sent for gait analysis at regular intervals before, during and after treatment. In this way, the progress of the patient over an extended period is recorded, and the long term effects of treatment may be quantified. Some examples of the ways in which the walkway has been used are given below. Table 1 Mean values of gait parameters in parenthesis.
recorded
for normal
niiw
DIS,TyE
% yy’
Mean
sample
age
Kg
5-9
13
6.77 (1.17)
24.92 (5.65)
1.25 (0.09)
5.74 (2.63)
0.53 (0.08)
lo-19
54
13.04 (1.77)
44.3 1 (10.57)
1.55 (0.11)
5.56 (4.43)
20-29
27
24.00 (273)
64.26 (11.10)
1.71 (0.09)
30-39
20
34.00 (2.66)
59.00 (10.60)
40-49
9
43.67 (2.55)
63.67 (10.25)
53.69
60.62
50-59
13
(3.25)
(5.64)
63.90 60-69
10
(3.35)
64.30 (7.76)
7&79
11
(2.87)
60.55 (4.06)
. . . . .
6 . . . . ..”
FILIrn
@am 0
*
*...f.wm .
-0 .
Figure 3 Assessment replacement aged 5-79
. . . . . . . ..‘~
. . . . . . . . . *...;“““‘*“““““;““““““““‘y
y.w...w..*.;“*“*”
subjects
. . . . .
“...,‘~
STiYT,*
8
Size of
. .
;*““““““““‘;‘“”
Mean stride time
Age range
...“.“.”
5(YE,I
Mean swing time
Mean height m
75.36
.
““““‘~
Contact time Mean asymmetry as contact % of stride time time S
MealI weight
mm,
mm0
::h y.v,
0
0
*o
*o
. . . . . . ;““...*+*wy......+
0
.
-0
‘I
. . . . . . . . . . . ;“‘*
11 days after left total hip
years of age. Standard
deviations
are shown
8
Stride ler@h a~ % of height
Velocity m C’
Cadence steps miri’
Foot placement asymm etry %
0.51 (0.08)
1.04 (0.12)
8219 (10.40)
1.08 (0.15)
117.69 (14.53)
6.31 (5.99)
0.57 (0.07)
0.49 (0.07)
1.06 (0.10)
85.53 (7.66)
1.30 (0.15)
115.19 (1209)
3.59 (3.61)
4.69 (3.95)
0.65 (0.09)
0.46 (0.05)
1.12 (0.10)
81.10 (8.42)
1.27 (0.18)
108.52 (9.76)
5.04 (4.82)
1.70 (0.10)
4.28 (4.08)
0.60 (0.08)
0.49 (0.07)
1.09 (0.08)
83.49 (10.06)
1.35 (0.27)
111.15 (8.07)
6.00 (4.21)
1.70 (0.07)
5.54 (3.36)
0.62 (0.10)
0.51 (0.09)
1.12 (0.10)
84.56 (9.54)
1.31 (0.04)
107.78 (10.89)
(2.85)
1.67
7.82
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(5.02)
0.59 (0.09)
0.54 (0.10)
1.13 (0.14)
81.34 (9.54)
1.27 (0.30)
107.77 (13.11)
3.23 (4.04)
1.60 (0.12)
5.42 (4.43)
0.66 (0.09)
0.44 (0.07)
1.11 (0.13)
78.51 (7.69)
1.16 (0.18)
109.60 (11.89)
5.80 (3.82)
1.64 (0.07)
6.19 (2.94)
0.60 (0.05)
0.49 (0.04)
1.09 (0.05)
72.23 (3.89)
1.19 (0.09)
110.09 (5.13)
5.09 (2.43)
298 J. Biomed. Eng. 1983, Vol. 5, October
2.89
Gait analysb: G. Gifford and J. Hughes
cosmetic symmetry of the gait pattern had returned and the stride length had increased to within normal limits. The patient’s velocity was still quite slow, and he still required the extra stability provided by the stick, but the patient now had a symmetrical painless gait, indicating a good operative result. 111
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MONITORING GAIT CHANGES AFTER SOFT TISSUE RELEASE (STR) AT THE HIP
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Figure 4 Assessment 5 months after left total hip replacement
sensation of the contact time and swing time values, and serves to emphasise any gross asymmetry of the temporal aspects of the gait. The ‘mean distance factor’ graph shows the relative positions of the left and right heel contact. It can be seen that the longer step was taken with the left foot. The RPC (relative position of contact) value of 100/25 is a quantitative measure of this step length asymmetry and shows that the right step length was one half of that required for symmetrical gait (normal value 100/50). In Fz&re 3, the assessment taken eleven days post-operatively, some immediate improvements can be seen. The velocity had increased almost four-fold, as a consequence of the great improvements in both stride length and cadence. The improvement of step length symmetry can be seen in the ‘mean distance factor’ graph, and the positioning of the aids in this graph suggests that they were being used more for stability than for protection. The asymmetry of contact time between left and right foot was still present but this may have been due to the patient’s unwillingness to overstress the new joint. The final assessment of patient Pl taken five months after operation (Figure 4) shows that the
Patient 2 was a thirteen-year-old female with an inflammatory mono-arthritis of the right hip. She developed a painful right hip which, despite active physiotherapy and night traction, became rapidly stiff and painful. The assessments presented were carried out pre-operatively, and two weeks and six weeks post-operatively. For reasons of space, full print-outs are omitted, but the trends for the five most important variables are presented graphically in Figure 5. Improvement is signified by upward trends in the top three graphs and downward trends in the bottom two. It can be seen that four of the variables (velocity, cadence, stride length and foot placement asymmetry) had regressed at the second assessment (two weeks ost-operative), but by the third assessment Qsix weeks post-operative) they had recovered to their former level. Contact time asymmetry showed a remarkable improvement from 21% pre-operatively to 1% two weeks post-operatively and 2% six weeks post-operatively, both post-operative values being within normal limits for this variable. Although the improvement was evident clinically, numerical validation of this can be most useful, particularly if it is required to compare the results of different forms of treatment. MONITORING GAIT CHANGES AFTER INTRA-ARTICULAR STERIOD INJECTIONS Patient 3 was a female aged seven who had systemic onset of JCA at the age of one and a half years. All the joints had been causing problems, with slight limitation of movement of both hips. The knees were painful and swollen, although the 140-I
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Figure 5 Graphical representation of information from print-outs of assessments before, two weeks after and six weeks after surgery to release the soft tissue at the hip
1 Assessment
Assessment
s
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2 Assessment
Assessment
Figure 6 Graphical representation of information from print-outs of assessments before and one week after injections of steroid into both knees
J. Biomed. Eng. 1983, Vol. 5, October
299
Gait analysk
%
G. Giffoord and J. Hughes
Assessment
z
Assessment
The plaster was applied with the knee in as corrected a position as possible, and worn for a period of four days. Pre-treatment assessment (assessment 1) showed a considerable degree of asymmetry in both contact time and foot placement. The posttreatment assessment taken six days later (assessment 2) showed contact time asymmetry to have been reduced to within normal limits, and a significant improvement was seen in foot placement symmetry. Velocity, cadence and stride length also showed improvement.
Assessment
Figure 7 Graphical representation of information from print-outs of assessments before and 6 days after application of a serial plaster for contracture of the left knee
Clinically the im rovement in the range of movement was small P5’) and it is probable that the re-education which had clearly taken place would have been overlooked without objective assessment figures.
range of movement was near normal, with only a slight limitation of flexion on the right. A bilateral intra-articular steriod injection was performed.
TESTING THE IMMEDIATE PHYSIOTHERAPY
Assessment
Assessment
Graphs of data taken from her print-outs can be seen in Figure 6. In the first assessment (preinjection), all gait parameters except cadence were below normal for her age. In the second assessment (one week post-injection) there was a marked improvement in the asymmetry parameters but little change in velocity, cadence or stride length. The reasons for this are not clear, but it is probable that the injections relieved the pain, allowing a return to symmetry, but the poor gait remained, due to limitation of movement of the hips.
TESTING
THE EFFECT
OF SERIAL
PLASTERING
Fipre 7 shows the effect on gait of serial plastering on a four-year-old male with mono-articular arthritis of the left knee. He had a 30’ fixed flexion deformity with little movement in either direction. Examination under anaesthetic showed some movement to be possible and serial plastering to improve extension was suggested.
EFFECT
OF
Patient 5 was a six-year-old female with a recent onset of juvenile chronic arthritis involing hips, knees and ankles. Routine physiotherapy for patients with JCA who are in hospital involves twice-daily exercise sessions both in and out of the pool, in which all joints are put through a full range of movement. The children suffer from some degree of morning stiffness, and the first physiotherapy session of the day helps to relieve this. The two assessments were carried out before and after the mornin physiotherapy session, which lasted one hour ksee Figure 8). The first assessment shotied excessive foot placement asymmetry (24%) which decreased to within normal limits (6%) in the second assessment. The small increase in contact time asymmetry from 4% to 10% was not considered a significant deterioration, as it is close to normal limits for her age group. Thus the beneficial effect of physiotherapy can be demonstrated over a short period of time.
80
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Figure 8 Graphical representation of information from print-outs of assessments before and after one hour of physiotherapy
300 J. Biomed. Eng. 1983, Vol. 5, October
60 50 40 u) 20 lo 0
Stick Crutches Frame Normal
Figure 9 Histogram to show comparative performance of patient using different walking aids. All measurements were taken on the same occasion. Normal data is presented for reference
Gait analysis: G. Cifford and J. Hughes
LONG-TERM MONITORING As mentioned in the introduction, records of gait analysis can be made routinely to monitor gait performance over a long period. The activity of the disease may fluctuate, and different therapies may affect walking ability. Provided these are taken into account when analysing results, accurate assessments of progress or deterioration can be made.
Figure 10 Graphical representation of a single patient’s assessments carried out over a two year period. Normal values are presented alongside with standard deviations in parentheses 1. represents an operation to correct the position of the left hip 2. represents the onset of deterioration
of the left knee
COMPARISON OF WALKING AIDS Assessment of correct walking aids is important, and needs constant review due to the condition of the weightbearing joints. For example, prolonged use of elbow crutches puts excessive strain on the shoulders. Gait analysis can provide help with this assessment, as several walks with different aids can single out the one which gives the most symmetrical gait. The types of walking aid most commonly used by these patients are sticks, elbow crutches and a wheeled high frame. Figure 9 shows the results of an assessment of one patient using all three types of aid compared to normal values for his age. This showed a marked improvement in velocity and stride length when using the high wheeled frame, combined with some improvement in both foot placement and contact time symmetry. Results from a number of such assessments have shown that in the majority of patients the most symmetrical gait is achieved when using the high wheeled frame, but this type of information needs to be considered together with the clinical assessment.
F@re 10 shows a graphic representation of one patient who has been assessed for more than two years. The first assessment shown was taken in January 1980 when th e patient was nine-years old. He had a rapid systematic onset of JCA at the age of five and had problems with many joints but the left hip became very stiff and he had an operation to correct the position of this hip in June 1980. The graph shows the change in his gait performance following surgery and provides an accurate record of his activity at each assessment. CONCLUSION Gait analysis by a microcomputer connected to a conductive walkway has been shown to provide useful objective data in a number of clinical situations. Its usefulness as a monitor of ait changes over short or long periods has been diemonstrated and it is envisaged that a system such as this would be of particular value to physiotherapists who, in general, lack objective data about their patients. The system is both quick and easy to use and the results are readily understandable and it is hoped, therefore, that systems such as this one will be used more widely in the clinical field in future. REFERENCES 1
2
Gifford, G. A microprocessor controlled system for measuring the temporal/distance factors of gait. A thesis submitted for the degree of Doctor of Philosophy of the Council for National Academic Awards School of Engineering and Science. The Polytechnic of Central London. August 1981. Gifford, G. and Hutton, W.C. A microprocessor controlled system for evaluating treatments for disabilities affecting the lower limb, J. Biomed. Engng. 1980, 2, 45
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October 301