Demographic characteristics, walking speed, and pain
Table 1 summarizes the demographic characteristics of the participants and clinical informationin the present study. There were no significant differences in age, height, weight, or walking speed between the hip OA and control groups. The hip OA group included three patients with KL grade 3 and 12 with KL grade 4.
Table 1. Demography and walking speed
|
Hip OA (n=15)
|
Control (n=15)
|
P value
|
Age, years
|
60.4 (9.6)
|
61.2 (6.3)
|
0.780
|
Height, cm
|
152.8 (2.9)
|
155.8 (3.7)
|
0.174
|
Weight, kg
|
57.1 (11.4)
|
53.5 (7.3)
|
0.329
|
Walking speed, km/h
|
1.2 (0.3)
|
1.3 (0.4)
|
0.636
|
OA KL grade 3 (moderate)
|
3 cases
|
|
|
OA KL grade 4 (severe)
|
12 cases
|
|
|
Harris hip score, point
|
45.1 (15.3)
|
|
|
Data are presented as mean (standard deviation). OA, osteoarthritis; KL, Kellgren and Lawrence.
In the hip OA group, the NRS painscore was significantly lower at 50% BW condition than at the 100% (P=0.002) and 75% (P=0.018) BW conditions. Moreover, the NRS pain score was significantly lower at 75% BW condition than at 100% BW condition (P=0.026) (Fig. 3).
MDCs on the spatiotemporal gait parameters and the peak hip/knee/ankle joint angles
MDCs on the spatiotemporal gait parameters and the peak hip/knee/ankle joint angles were as follows: 12.1cm, for the step length; 18.4step/min, for the cadence; 5.1°, for the peak hip flexion angle; 3.4°, peak hip extension angle; 3.9°, peak hip abduction angle; 2.5°, peak hip adduction angle; 3.3°, peak hip external rotation angle; 3.6°, peak hip internal rotation angle; 7.0°, peak knee flexion angle; 3.5°, peak knee extension angle; 5.9°, peak ankle dorsiflexion angle; and 5.2°, peak ankle plantar flexion angle.
Spatiotemporal gait parameters
For the step length, two-way ANOVA showed a statistical difference between the groups (P=0.027) but not between theBW conditions (100%, 75%, and 50%) (P=0.536). No interaction was detected between the groups and BWconditions (P=0.147) (Table 2). Post hoc Bonferroni tests showed thatthe step length in all BW conditions in the hip OA group decreased compared withthat in the control group (P<0.001). For the cadence, two-way ANOVA did not show a significant difference between the groups (P=0.167) and BW conditions (100%, 75%, and 50% BW) (P=0.219). No interaction was detected between the groups and BWconditions (P=0.052) (Fig. 4).
Table 2. The spatiotemporal gait parameters and peak angles of the hip, knee, and ankle joints
Variables
|
Group
|
100% BW
|
75% BW
|
50% BW
|
Effect size
(group)
|
Effect size
(unweighting)
|
Step length, cm
|
Hip OA
Control
|
25.3
(14.9–35.6)
40.3
(20.0–50.7)
|
23.3
(13.1–33.6)
46.5
(36.2–56.8)
|
24.5
(14.5–34.4)
40.7
(30.7–50.6)
|
0.83
|
N/A
|
Hip FLX, degree
|
Hip OA
Control
|
22.0
(16.8–27.1)
25.6
(20.5–30.8)
|
20.1
(15.2–24.9)
24.4
(19.6–29.2)
|
16.2
(11.8–20.6)
21.0
(16.6–25.4)
|
N/A
|
0.05
|
Hip EXT, degree
|
Hip OA
Control
|
−0.9
(−4.0–2.3)
−4.5
(−7.7–−1.4)
|
0.0
(−2.9–3.0)
−3.9
(−6.8–−0.9)
|
−0.6
(−3.4–2.2)
−4.8
(−7.6–−2.0)
|
0.04
|
N/A
|
Hip ADD, degree
|
Hip OA
Control
|
2.0
(0.2–3.8)
4.6
(2.8–6.4)
|
1.7
(0.1–3.4)
3.3
(1.7–4.9)
|
0.1
(−1.1–1.4)
2.3
(0.9–3.8)
|
N/A
|
0.01
|
Hip IR, degree
|
Hip OA
Control
|
7.4
(4.5–10.3)
7.4
(4.5–10.3)
|
6.3
(3.6–9.0)
5.9
(3.2–8.5)
|
5.0
(2.7–7.2)
6.1
(3.8–8.3)
|
N/A
|
0.01
|
Knee FLX, degree
|
Hip OA
Control
|
47.2
(37.6–56.8)
59.9
(50.3–69.5)
|
44.0
(34.1–53.8)
54.7
(44.9–64.6)
|
39.3
(30.8–47.8)
51.9
(43.4–60.4)
|
N/A
|
0.11
|
Knee EXT, degree
|
Hip OA
Control
|
−7.1
(−9.8–−4.5)
−3.5
(−6.2–−0.9)
|
−4.5
(−6.5–−2.5)
−3.4
(−5.5–−1.5)
|
−2.8
(−4.8–−1.0)
−2.3
(−4.2–−0.5)
|
N/A
|
0.01
|
Ankle PF, degree
|
Hip OA
Control
|
5.5
(−0.1–11.4)
7.0
(1.2–12.8)
|
10.0
(3.9–16.3)
11.4
(5.2–17.6)
|
11.1
(4.3–17.9)
14.6
(7.8–21.4)
|
N/A
|
0.08
|
Data are presented as mean (95% CI). OA, osteoarthritis; BW, body weight; FLX, flexion; EXT, extension; ADD, adduction; IR, internal rotation; PF, plantar flexion.
Effects of unweighting on the peak hip/knee/ankle joint angles
For the peak hip flexion angle during the swing phase, two-way ANOVA showed a significant difference between theBW conditions (P<0.001) but not between the groups(P=0.163). No interaction was detected between the groups and BWconditions (P=0.910) (Fig. 5A). Post hoc Bonferroni tests showed that the peak hip flexion angle at 50% BW condition in both groupsdecreased statistically significantly compared withthat at 100% BW condition(hip OA, P=0.011; control, P=0.049). For the peak hip abduction and external rotation angles during the stance phase, two-way ANOVA did not show a significant difference between the groups and BW conditions. No interaction was detected between the groups and BWconditions.
For the peak hip extension angle during the stance phase, two-way ANOVA showed a significant difference between thegroups (P=0.044) but not between theBW conditions (P=0.682). No interaction was detected between the groups and BWconditions (P=0.950) (Fig. 5B). Post hoc Bonferroni tests showed that the peak hip extension angle in all BW conditions in the hip OA group decreased compared with that in the control group (P<0.001).For the peak hip adduction and internal rotation angles during the swing phase, two-way ANOVA showed significant differences between theBW conditions (adduction, P<0.001; internal rotation, P=0.002) but not between the groups. No interaction was detected between the groups and BWconditions. Post hoc Bonferroni tests showed that the peak hip adduction angle at 50% BW condition in the control group decreased statistically significantly compared with that at 100% BW condition (P=0.012). Post hoc Bonferroni tests showed that the peak hip internal rotation angle at 50% BW condition in the hip OA group decreased statisticallysignificantly compared with that at 100% BW condition (P<0.001).
For the peak knee flexion and extension angles, two-way ANOVA showed a significant difference between theBW conditions (P<0.001) but not between the groups. No interaction was detected between the groups and BWconditions (Fig. 6A). Post hoc Bonferroni tests showed that the peak knee flexion angle at 50% BW condition in both groups decreased statistically significantly compared withthat at 100% BW condition(hip OA, P=0.002; control, P=0.002)and the peak knee extension angle at 75% and 50% BW conditions in the hip OA group decreased statistically significantly compared with that at 100% BW condition (75% vs. 100% BW,P=0.029;50% vs. 100% BW,P<0.001).
For the peak ankleplantar flexionangle, two-way ANOVA showed a significant difference between theBW conditions (P<0.001) but not between the groups. No interaction was detected between the groups and BWconditions (Fig. 6B). Post hoc Bonferroni tests showed that the peak ankle plantar flexion angle at 50% BW condition in both groups increasedstatistically significantly compared with that at 100% BW condition(hip OA, P=0.020; control, P=0.001).
Table 2 summarizes the effect sizes of each parameter that two-way ANOVA showed significant differences in the present study. The effect size of the step length between the groups was large (η2=0.83). The effect sizes of the peak knee flexion and ankle plantar flexionangles were medium (η2=0.11 and η2=0.08). The effect sizes of other parameters were small.