We compared the differences in active and passive force exertion under the passive mode of the Lokomat exoskeleton robot between patients with complete spinal cord injuries and healthy subjects. We hypothesized that the CTRL group will behave the same as the SCI group in passive mode, meaning that a significant finding will take the form of a notable difference between the active tasks of the CTRL group and those of the SCI group; thus, unless specifically noted, all p-values compare active tasks between the CTRL and SCI groups.
Conventional parameter results
In this study, we categorized the peak values as positive and negative. Significant differences were observed in the hip joints for negative torque peak values (left, hip P = 0.000; right, hip P = 0.000), but not uniformly in the knee joints (left, knee P = 0.066; right, knee P = 0.037). The results for positive torque peak valueswere the opposite (left, hip P = 0.083; right, hip P = 0.031). We used the of overall task torque to measure the control during gait, but the actual statistical results lack interpretability and practical significance. The results of represent the duration of force exertion when the torque is positive. These results showed relevance in the knee joints for both positive and negative torques with positive (left, knee P = 0.037; right, knee P = 0.000) and negative (left, knee P = 0.000; right, knee P = 0.000). For the left hip joint, the negative results were not significant (left, hip P = 0.071; right, hip P = 0.000), but the positive results were (left, hip P = 0.071; right, hip P = 0.000). In terms of the RTD indicating explosive power, the hip joints showed significant differences in positive RTD (left, hip P = 0.002; right, hip P = 0.001) but no significant differences in negative RTD (left, hip P = 0.06; right, hip P = 0.269). However, the RTD, irrespective of whether it was positive (left, knee P = 0.019; right, knee P = 0.001) or negative (left, knee P = 0.001; right, knee P = 0.000), showed significant differences in the knee joints. The results are presented in Table 1.
New parameter results
The novel method proposed in this paper, which assesses high- and low-frequency energy in the knee and hip joints through time-frequency analysis of wavelet transforms, showed significant differences, as did the high-frequency wavelet coefficient (left, hip P = 0.016; right, hip P = 0.030, left, knee P = 0.000; right, knee P = 0.000), low-frequency wavelet coefficient (left, hip P = 0.016; right, hip P = 0.005, left, knee P = 0.000; right, knee P = 0.000), and TDGP (left, hip P = 0.000; right, hip P = 0.000, left, knee P = 0.000; right, knee P = 0.000)
Table 1 The table should be referenced in 254 line and its’ description should be referenced in 255 line.
Table 1. The first row conducts t-tests between CA and SA; the second row performs t-tests between the CP and SP; and the third row conducts t-tests between SA and SP. An asterisk (*) indicates P ≤ 0.05.
Feature
|
Left hip value (mean ± SE)
|
Right hip value (mean ± SE)
|
Left knee value (mean ± SE)
|
Right knee value (mean ± SE)
|
Peak_p
|
|
|
|
|
CTRL-Active (CA)
|
63.09 ± 6.23
|
65.58 ± 5.39*
|
45.21 ± 3.07*
|
45.49 ± 3.76*
|
CTRL-Passive (CP)
|
33.20 ± 4.00
|
35.89 ± 2.59
|
26.72 ± 2.35*
|
27.47 ± 2.39*
|
SCI-Active (SA)
|
46.97 ± 5.21
|
46.53 ± 5.85
|
14.46 ± 2.45
|
17.26 ± 2.23
|
SCI-Passive (SP)
|
47.76 ± 6.42
|
47.44 ± 6.69
|
13.54 ± 2.10
|
15.56 ± 1.77
|
Peak_n
|
CA
|
–96.49 ± 7.77*
|
–89.56 ± 6.73*
|
–29.83 ± 4.18
|
–28.60 ± 4.14*
|
CP
|
–50.97 ± 3.94
|
–46.44 ± 3.32*
|
–18.29 ± 2.36
|
–15.64 ± 1.53
|
SA
|
–36.71 ± 3.70
|
–33.91 ± 3.10
|
–18.93 ± 2.58
|
–17.99 ± 2.11
|
SP
|
–35.51 ± 4.23
|
–32.95 ± 3.46
|
–19.25 ± 2.80
|
–18.10 ± 3.19
|
Positive TFI
|
CA
|
1.41 ± 0.04*
|
1.51 ± 0.03
|
1.84 ± 0.06*
|
1.79 ± 0.08*
|
CP
|
1.52 ± 0.05
|
1.59 ± 0.04
|
1.47 ± 0.13
|
1.49 ± 0.12
|
SA
|
1.69 ± 0.06
|
1.62 ± 0.09
|
1.10 ± 0.03
|
1.17 ± 0.11
|
SP
|
1.61 ± 0.04
|
1.57 ± 0.04
|
1.18 ± 0.05
|
1.25 ± 0.11
|
Negative TFI
|
CA
|
–1.46 ± 0.08*
|
–1.49 ± 0.07*
|
–1.12 ± 0.03*
|
–1.05 ± 0.02
|
CP
|
–1.79 ± 0.08
|
–1.70 ± 0.09*
|
–0.97 ± 0.03
|
–0.90 ± 0.03
|
SA
|
–1.17 ± 0.05
|
–1.12 ± 0.05
|
–0.90 ± 0.09
|
–0.99 ± 0.05
|
SP
|
–1.38 ± 0.07*
|
–1.13 ± 0.05
|
–1.04 ± 0.05
|
–1.02 ± 0.08
|
Positive TI
|
CA
|
34.79 ± 1.78*
|
37.85 ± 2.12*
|
51.27 ± 4.72*
|
44.46 ± 2.66*
|
CP
|
16.81 ± 2.48*
|
19.45 ± 1.95*
|
26.88 ± 4.88
|
26.17 ± 2.96*
|
SA
|
50.31 ± 4.67
|
50.71 ± 4.46
|
37.52 ± 2.27
|
26.39 ± 1.52
|
SP
|
39.43 ± 2.71
|
40.02 ± 3.63
|
26.87 ± 2.95*
|
17.55 ± 1.66*
|
Negative TI
|
CA
|
–76.87 ± 8.25
|
–77.93 ± 3.96*
|
–77.04 ± 1.73*
|
–56.13 ± 0.74*
|
CP
|
–56.07 ± 4.96
|
–60.67 ± 2.65*
|
–45.09 ± 1.75
|
–32.27 ± 1.10*
|
SA
|
–57.14 ± 1.75
|
–53.61 ± 2.08
|
–35.15 ± 4.32
|
–20.11 ± 1.14
|
SP
|
–46.69 ± 3.29
|
–48.31 ± 2.44
|
–33.61 ± 2.62
|
–18.07 ± 1.98
|
RTD - positive
|
CA
|
1435.09 ± 149.89*
|
1083.67 ± 67.67*
|
501.84 ± 75.94
|
410.22 ± 17.51*
|
CP
|
772.63 ± 44.67
|
781.85 ± 52.87
|
315.06 ± 12.52
|
329.39 ± 11.73*
|
SA
|
756.66 ± 47.55
|
691.36 ± 22.89
|
292.66 ± 15.27
|
328.27 ± 13.06
|
SP
|
742.08 ± 53.17
|
663.78 ± 47.46
|
291.15 ± 12.06
|
295.58 ± 15.10
|
RTD - negative
|
CA
|
–1100.65 ± 101.28
|
–929.78 ± 36.60*
|
–651.17 ± 78.29*
|
–565.30 ± 40.66*
|
CP
|
–860.16 ± 39.81
|
–849.90 ± 40.39
|
–330.89 ± 42.15
|
–409.04 ± 22.13*
|
SA
|
–845.45 ± 27.31
|
–996.34 ± 45.68
|
–291.38 ± 24.62
|
–288.06 ± 36.64
|
SP
|
–902.05 ± 44.27
|
–850.29 ± 59.71
|
–274.29 ± 20.34
|
–270.91 ± 25.55
|
High-frequency wavelet coefficient
|
CA
|
34.46 ± 2.33*
|
33.74 ± 1.92*
|
18.30 ± 1.03*
|
17.69 ± 1.11*
|
CP
|
23.03 ± 1.36
|
23.27 ± 1.32
|
12.29 ± 1.04
|
12.99 ± 1.26
|
SA
|
24.84 ± 2.74
|
25.41 ± 3.26
|
8.73 ± 0.88
|
9.66 ± 1.05
|
SP
|
25.04 ± 2.24
|
25.56 ± 2.82
|
8.69 ± 0.80
|
9.81 ± 1.02
|
Low-frequency wavelet coefficient
|
CA
|
136.17 ± 9.87*
|
129.63 ± 9.35*
|
63.82 ± 4.41*
|
59.06 ± 3.85*
|
CP
|
81.38 ± 5.02
|
80.26 ± 4.91
|
38.52 ± 3.99*
|
42.14 ± 5.02
|
SA
|
86.62 ± 11.45
|
83.22 ± 11.26
|
28.03 ± 3.25
|
27.89 ± 3.46
|
SP
|
85.64 ± 8.74
|
85.93 ± 9.94
|
27.87 ± 3.43
|
27.65 ± 4.02
|
TDGP
|
CA
|
10.67 ± 0.83*
|
11.41 ± 0.66*
|
5.55 ± 0.48*
|
5.41 ± 0.43*
|
CP
|
3.00 ± 0.37
|
3.16 ± 0.36
|
1.63 ± 0.18
|
1.59 ± 0.24
|
SA
|
3.22 ± 0.68
|
3.26 ± 0.45
|
1.52 ± 0.30
|
1.55 ± 0.23
|
SP
|
2.26 ± 0.33
|
2.47 ± 0.40
|
0.99 ± 0.15
|
1.07 ± 0.16
|