4. Walking speed
• Best measured independently of gait
analysis.
• Walk tests as far as possible in a given
time
– 6 minute walk test (6MWT)
– 2 minute walk test (2MWT)
– 1 minute walk test (1MWT)
4
ATS statement: guidelines for the six-minute walk test.
Am J Respir Crit Care Med, 2002. 166(1): p. 111-7.
5. 6 minute walk test
5
ATS statement: guidelines for the six-minute walk test.
Am J Respir Crit Care Med, 2002. 166(1): p. 111-7.
6. 1 minute walk test
6
McDowell, B.C., et al., Validity of a 1 minute walk test for children with cerebral palsy.
Developmental Medicine and Child Neurology, 2005. 47(11): p. 744-8.
7. 1 minute walk test
7
McDowell, B.C., et al., Test-retest reliability of a 1-min walk test in children with bilateral
spastic cerebral palsy (BSCP). Gait and Posture, 2009. 29(2): p. 267-9.
No equivalent data for self-selected walking speed?
(After practice walk)
10. Should really be tested
10
Schwartz MH, Koop SE, Bourke JL, Baker R.
A nondimensional normalization scheme for oxygen utilization data.
Gait Posture. 2006; 4(1):14-22.
“Raw” “By mass” “Non-dimensional”
13. Gait indices
Single number to reflect the quality of gait.
• Gillette Gait Index (GGI, normalcy index)
• Gait deviation index (GDI)
• Gait profile score (GPS)
13
14. Gillette Gait Index
• Originally called “Normalcy” index
• Doesn’t feel right!
– Small number of parameters
– Mixes temporal-spatial and kinematics
– Black box
– No significance to values
– Forgot to take the square root!
14
15. GPS an GDI
The same measure scaled in two different ways.
15
An New Method for Computing the Gait Deviation Index and Motion Analysis Profile
Schwartz, Rozumalski and Baker, GCMAS 2013
𝐆𝐃𝐈 ≈ 𝟏𝟎𝟎 − 𝟏𝟎 ×
𝐥𝐧 𝑮𝑷𝑺 − 𝑨
𝑩
𝐆𝐏𝐒 ≈ 𝐞𝐱𝐩
𝐁(𝟏𝟎𝟎 − 𝐆𝐃𝐈)
𝟏𝟎
+ 𝑨
A = mean ln RMS , and B = sd ln RMS
Absolutely no point calculating both
– they tell you the same thing!
16. GPS and GDI
• GPS simple score (how many degrees
different from normal)
– About 6º is normal
• GDI –
– 100 = normal
– 10 points = one standard deviation
16
17. 17
Baker, R., et al., The gait profile score and movement analysis profile.
Gait Posture 2009;30(3):265-9.
GPS and GDI
18. 18
Baker, R., et al., The gait profile score and movement analysis profile.
Gait Posture 2009;30(3):265-9.
GPS and GDI
20. Gait profile score vs GMFCS
Baker R, McGinley JL, Schwartz MH, Beynon S, Rozumalski A, Graham HK, et al.
The gait profile score and movement analysis profile.
Gait Posture. 2009; 30(3):265-9.
21. Gait profile score vs FAQ
Baker R, McGinley JL, Schwartz MH, Beynon S, Rozumalski A, Graham HK, et al.
The gait profile score and movement analysis profile.
Gait Posture. 2009; 30(3):265-9.
23. Gait profile score vs clinical opinion
Beynon S, McGinley JL, Dobson F, Baker R.
Correlations of the Gait Profile Score and the Movement Analysis Profile relative to clinical judgments.
Gait Posture. 201;32(1):129-32.
24. MAP vs clinical opinion
Beynon S, McGinley JL, Dobson F, Baker R.
Correlations of the Gait Profile Score and the Movement Analysis Profile relative to clinical judgments.
Gait Posture. 201;32(1):129-32.
25. Minimal clinically important difference
25
Baker R, McGinley JL, Schwartz M, Thomason P, Rodda J, Graham HK. The minimal clinically
important difference for the Gait Profile Score. Gait Posture. 2012;35(4):612-5.
MCID = 1.6°
27. Change in GPS following SEMLS
27
y = 0.16x + 8.10
R² = 0.07
y = 0.12x + 10.77
R² = 0.04
0°
5°
10°
15°
20°
25°
30°
0° 5° 10° 15° 20° 25° 30°
PostoperativeGPS
PreoperativeGPS
GMFCS II
GMFCS III
95% normal range
90%
80%
50%
28. Change in GPS following SEMLS
28
y = 0.84x - 8.10
R² = 0.68
y = 0.88x - 10.77
R² = 0.68
-10°
-5°
0°
5°
10°
15°
20°
0° 5° 10° 15° 20° 25° 30°
Improvement(decrease)inGPS
Pre-operative GPS
GMFCS II
GMFCS III
95% normal range
90%
80%
50%
+MCID
-MCID
29. Change in GPS following SEMLS
29
If we analyse all these children as a group
then we might conclude that surgery
improves gait quality for all children.
If we look at the underlying data we realise
that it only really benefits the more severely
affected children.
30. MCID
30
y = 0.84x - 8.10
R² = 0.68
y = 0.88x - 10.77
R² = 0.68
-10°
-5°
0°
5°
10°
15°
20°
0° 5° 10° 15° 20° 25° 30°
Improvement(decrease)inGPS
Pre-operative GPS
GMFCS II
GMFCS III
95% normal range
90%
80%
50%
+MCID
-MCID
66% of children had a change
of greater than MCID.
Improved
31. MCID
31
y = 0.84x - 8.10
R² = 0.68
y = 0.88x - 10.77
R² = 0.68
-10°
-5°
0°
5°
10°
15°
20°
0° 5° 10° 15° 20° 25° 30°
Improvement(decrease)inGPS
Pre-operative GPS
GMFCS II
GMFCS III
95% normal range
90%
80%
50%
+MCID
-MCID
66% of children had a change
of greater than MCID.
Improved
32% of children had a change a
change of less than MCID either way.
No change
32. MCID
32
y = 0.84x - 8.10
R² = 0.68
y = 0.88x - 10.77
R² = 0.68
-10°
-5°
0°
5°
10°
15°
20°
0° 5° 10° 15° 20° 25° 30°
Improvement(decrease)inGPS
Pre-operative GPS
GMFCS II
GMFCS III
95% normal range
90%
80%
50%
+MCID
-MCID
66% of children had a change
of greater than MCID.
Improved
32% of children had a change a
change of less than MCID either way.
No change
2% of children deteriorated by more
than MCID
Deteriorated
34. Detecting change
Statistically importance
To have 95% confidence that 2 measures
are different the change needs to be 3 times
the standard error of measurement (SEM)
• Need to know the SEM.
• Can be quite large for many clinical
measures.
34
35. Detecting change
Statistically importance
35
McGinley JL, Baker R, Wolfe R, Morris ME.
The reliability of three-dimensional kinematic gait measurements: a systematic review.
Gait Posture. 2009 Apr;29(3):360-9.
x3!
36. Detecting change
Statistically important change
36
McDowell BC, Hewitt V, Nurse A, Weston T, Baker R.
The variability of goniometric measurements in ambulatory children with spastic cerebral palsy.
Gait Posture. 2000 Oct;12(2):114-21.
x3!