Observational Study
Copyright ©The Author(s) 2016.
World J Orthop. Jun 18, 2016; 7(6): 383-391
Published online Jun 18, 2016. doi: 10.5312/wjo.v7.i6.383
Table 1 Summary of results
Participant characteristics Summary statistic Transtibial Transfemoral Able-bodied
Number Count 12 8 28
Number of women Count 3 3 16
Age (yr) Mean (SD) 61.7 (12.6) 63.3 (12.0) 60.6 (7.8)
BMI (kg/m2) Mean (SD) 27.3 (6.5) 25.4 (4.4) 25.6 (3.1)
Ageamp (yr) Mean (SD) 40.9 (19.2) 38.9 (23.0) NA
Time (yr) Median (IQR) 17.0 (27.3) 22.5 (38.5) NA
Use (h/d) Median (IQR) 15.5 (1.0) 13.0 (10.0) NA
Performance-based outcomes
GDI (-)aMean (SD) 81.2 (13.6) 68.8 (8.8) NA
nSL (-)abMean (SD) 0.76 (0.11) 0.65 (0.10) 0.87 (0.06)
nSSWS (/s)abMean (SD) 1.36 (0.27) 1.01 (0.23) 1.72 (0.19)
TUGT (s)abMedian (IQR) 10.0 (2.0) 12.7 (7.5) 7.9 (1.4)
6MWD (m)abMean (SD) 412 (91) 295 (85) 520.3 (56.2)
Self reported outcomes
AM (/100) Mean (SD) 78.4 (18.5) 64.0 (19.9) NA
AP (/100) Mean (SD) 72.2 (14.5) 63.0 (14.2) NA
FR (/100) Median (IQR) 76.0 (64.4) 67.6 (59.6) NA
PR (/100) Median (IQR) 94.7 (15.1) 95.8 (20.9) NA
RL (/100) Mean (SD) 63.4 (24.3) 64.7 (25.4) NA
SB (/100)aMedian (IQR) 93.6 (11.3) 80.13 (34.6) NA
SO (/100) Median (IQR) 70.5 (46.0) 85.3 (67.1) NA
UT (/100) Median (IQR) 77.9 (18.0) 68.3 (44.7) NA
WB (/100) Median (IQR) 86.2 (23.4) 53.8 (61.2) NA
aSignificant differences between transtibial and transfemoral amputees, P ≤ 0.05;
bSignificant differences between able-bodied and amputee groups. BMI: Body mass index measured with prosthesis on; IQR: Inter-quartile range; nSL: Leg-length normalised average step length; nSSWS: Leg-length normalised self selected walking speed; TUGT: Timed-up-and-go test; 6MWD: Six-minute walk distance; AM: Ambulation; AP: Appearance; FR: Frustration; PR: Perceived response; RL: Residual limb health; SB: Social burden; SO: Sounds; UT: Utility; WB: Well being; NA: Not available; GDI: Gait deviation index.
Table 2 Correlations with the gait deviation index, Spearman’s rank correlation coefficient displayed
ParameterCorrelation coefficient, ρ
Participant characteristics
Age -0.13
BMI -0.27
Age at amputation -0.16
Time since amputation 0.14
Performance-based outcomes
nSLpro  0.73b
nSLint0.83b
nSLave0.78b
nSSWS 0.7b
TUGT -0.60
6MWD   0.74b
Self-report measures
Ambulation 0.44
Appearance 0.22
Frustration -0.14
Perceived response 0.02
Residual limb health -0.22
Social burden 0.37
Sounds -0.01
Utility 0.33
Well-being 0.20
bP ≤ 0.001, indicates significant relationships. BMI: Body mass index measured with prosthesis on; nSL: Leg-length normalised average step length; nSSWS: Leg-length normalised self selected walking speed; TUGT: Timed-up-and-go test; 6MWD: Six-minute walk distance.
Table 3 Correlations between performance-based measures, Spearman’s rank correlation coefficient displayed
nSLpronSLintnSLavenSSWSTUGT
nSLint0.87
nSLave0.98 0.95
nSSWS 0.84 0.91 0.88
TUGT -0.70 -0.71 -0.71 -0.82
6MWD 0.86 0.89 0.89 0.96 -0.83
All correlations significant, P ≤ 0.001. nSL: Leg-length normalised average step length; nSSWS: Leg-length normalised self selected walking speed; TUGT: Timed-up-and-go test; 6MWD: Six-minute walk distance.
Table 4 Regression analysis; gait deviation index dependent variable
Independent variables
No. R2adjR2pred1234
All variables
1 70.9 56.8 nSLint
2 76.1 59.6 nSLintAM_C
3 82.6 66.5 nSLintAM_C tstand
4 89.3 81.4 nSLintAM_C tstand6MWD
No step-length parameters
1 68.6 60.4 6MWD
2 79.8 72.0 6MWD AM_C
3 86.1 82.7 6MWD AM_C tstand
4 90.2 86.2 6MWD AM_C tstandAge
Forced inclusion of walking speed
1 57.4 46.4 nSSWS
2 71.1 53.7 nSSWS AM_C
3 79.6 65.2 nSSWS AM_C tstand
4 82.1 70.7 nSSWS AM_C tstandUT_D1
1Not significant. Note 1: The table is organized such that the predicted gait deviation index is a function of the independent variables listed. The coefficients of the independent variables have been suppressed until the utility of these equations have been proven for use with individual patients; Note 2: Participants reporting an absence of frustration (n = 4) in the four weeks prior to testing were not included in the regression analysis. No.: Number of independent variables; R2adj: Adjusted R2; R2pred: Predictive R2; nSLint: Leg-length normalised intact limb step-length; tstand: Time to stand; AM_C: Over the past four weeks, rate your ability to walk up stairs when using your prosthesis; 6MWD: Six-minute walk distance; Age: Chronological age; nSSWS: Leg-length normalised self-selected walking speed; UT_D: Over the past four weeks, rate your comfort while standing when using your prosthesis.