Comparison of ankle–foot orthoses with plantar flexion stop and plantar flexion resistance in the gait of stroke patients: A randomized controlled trial

Abstract

Background:

The effect of plantar flexion resistance of ankle–foot orthoses on the ankle and knee joints is well known, but its effect on the hip joint and upper body movement during the gait of stroke patients remains unclear.

Objectives:

To compare the effect of an ankle–foot orthosis with plantar flexion stop and an ankle–foot orthosis with plantar flexion resistance on the gait of stroke patients in the subacute phase.

Study design:

Randomized controlled trial.

Methods:

A total of 42 stroke patients (mean age = 59.9 ± 10.9 years, 36 men and 4 women) in the subacute phase were randomized to each ankle–foot orthosis group in a parallel controlled trial with no blinding. Patients received gait training from physiotherapists using the specified ankle–foot orthosis for 2 weeks. Shod gait without an ankle–foot orthosis before training and gait with an ankle–foot orthosis after training were measured by three-dimensional motion analysis.

Results:

A total of 20 patients were analyzed in each group. Significant differences were found in pelvic and thoracic tilt angles between the two groups. Compared with the gait without an ankle–foot orthosis, the pelvis showed forward tilt when patients walked with an ankle–foot orthosis with plantar flexion stop, and the thorax showed decreased forward tilt when the patients walked with an ankle–foot orthosis with plantar flexion resistance.

Conclusion:

The difference in ankle–foot orthosis function in sagittal plantar flexion resistance affected the alignment of the upper body and the pelvis during the gait of stroke patients in the subacute phase.

Clinical relevance

Maintaining upright posture is important in gait rehabilitation. The findings of this study suggest that the ankle–foot orthosis with plantar flexion resistance facilitated better alignment of the upper body and pelvis during the gait of stroke patients in subacute phase. This type of ankle–foot orthosis could be beneficial for patients with malalignment of the upper body and pelvis.

Keywords

Gait analisys lower limb orthotics stroke

Background

Ankle–foot orthoses (AFOs) are frequently used to improve the gait of patients after stroke. The findings of many studies comparing gait with and without AFOs^1–3 suggest that AFOs are beneficial to velocity, ankle and knee joint kinematics, kinetics, and the energy cost of walking. There are many kinds of AFOs—articulated and non-articulated, rigid and dynamic—but the question of how to choose the appropriate AFO for each patient remains unanswered. It is therefore important to clarify the effect of AFO design characteristics on the gait of patients.

The main purposes of AFOs are to stabilize the ankle joint in stance phase, to facilitate toe clearance in swing phase, and to promote heel strike.⁴ Sagittal plane resistance to dorsiflexion and plantar flexion of the ankle joint is an important design characteristic of AFOs that helps improve these problems. Most non-articulated AFOs have dorsiflexion resistance, which has been found to assist the eccentric contraction of the plantar flexors and to stabilize the ankle and knee joints in stance.⁵ However, some studies have shown that articulated AFOs lacking dorsi flexion resistance showed larger increases in velocity and dorsiflexion angle in stance compared with the non-articulated AFOs.^6,7 Plantar flexion resistance facilitates toe clearance in swing phase and promotes heel strike. To prevent foot drop, most traditional AFOs restrict the movement of the ankle joint into plantar flexion. However, some studies have shown that restricted plantar flexion induces undesired knee flexion in early stance phase.^7,8 The plantar flexion resistance of AFOs also plays an important role in the first rocker function.^9,10 In normal gait, gradual movement into plantar flexion, supported by eccentric contraction of the dorsiflexors, controls shank rotation and achieves smooth weight shift to the leading limb in loading response.¹¹ Previous studies have shown the importance of adjusting an AFO’s plantar flexion resistance appropriately for each patient’s condition.¹² Kobayashi and colleagues^13–16 showed systematic change of ankle and knee joint kinematics and kinetics with increased AFO plantar flexion resistance. They demonstrated decreases in both ankle plantar flexion in early stance and knee extension in late stance and increased knee flexion in early stance in relation to the increased plantar flexion resistance of the AFO. Other studies have shown that AFOs with adjusted plantar flexion resistance significantly improve the gait of stroke patients compared with the shod gait without an AFO.^17,18 These results have helped clarify the effect of AFO plantar flexion resistance on the gait of stroke patients; however, the effects examined were limited to the ankle and knee joints, which are directly affected by AFO function. Moreover, the number of study subjects was limited.^13–18

The recovery of stroke patients begins at stroke onset, with the recovery curve rising to a plateau at around 6 months post onset.¹⁹ The subjects who participated in previous studies examining the effect of plantar flexion resistance were in the chronic phase, more than 181 days after onset.^13–18 Sensitive outcome measures of gait recovery have been shown to differ between patients in the chronic phase compared with the subacute phase.^19,20 This study was therefore performed to investigate the effect of the plantar flexion resistance of AFOs on the gait of stroke patients in the subacute phase. To accomplish this, the gait of patients with an AFO with plantar flexion stop (AFO-PS) and patients with an AFO with plantar flexion resistance were compared by a randomized controlled trial. Previous studies have suggested that plantar flexion stop induces increased dorsiflexion and knee flexion in the early stance phase of gait. This increase may induce the hip flexion. We therefore hypothesized that the kinetics and kinematics of the ankle, knee, and hip joints would be affected by AFO function.

Methods

Patients

The participants in this study were stroke patients in the subacute phase (less than 180 days after onset) who were undergoing rehabilitation at a rehabilitation center and had been prescribed the AFO and gait training using the AFO. Patients with ankle range of motion greater than 0° in dorsiflexion and spasticity grade less than 2 on the Modified Ashworth Scale²¹ were included. The inclusion criteria were so defined because patients with severe contracture or spasticity had difficulty walking without an AFO. Exclusion criteria were non-concurrent pathologies affecting the central nervous system or neuromuscular system, communication problems, and proprioceptive sensory impairment. Before participating in the study, patients received gait rehabilitation from physiotherapists, but did not use any kind of AFO. In all, 42 patients met the above criteria and participated in this study. Because the first measurement was done as patients began walking 10 m with supervision, patients were assigned to two groups in order of participation with no blinding: one group wore an AFO-PS and the other wore an AFO with plantar flexion resistance. All procedures were approved by the local ethics committee of the International University of Health and Welfare and Nakaizu rehabilitation center. Informed consent was obtained from all patients prior to their participation in the study.

Equipment and protocol

The two types of AFOs shown in Figure 1 were used in this study. An AFO with metal uprights and a Klenzak joint was used as the AFO-PS. The ankle of the AFO-PS does not move into plantar flexion. An AFO with metal uprights and a mechanical ankle joint with an oil damper (AFO-OD; Gait Solution; Kawamura Gishi) were used as the AFO with plantar flexion resistance.²² The ankle joint of the AFO-OD moves into plantar flexion with resistance that is generated by the oil damper. The magnitude of the resistance can be changed from 1 to 4 by rotating a screw located at the top of the oil damper; however, resistance was set at 3 in this study because this magnitude was used the most frequently for patients in the subacute phase. The ankle joints of both AFOs move freely into dorsiflexion. We chose AFOs with metal uprights because that type of AFO was used in previous studies that investigated the effect of plantar flexion resistance of AFOs on the gait of stroke patients.^13,15,16

Figure 1.

Ankle–foot orthoses (AFOs) used in this study: (a) AFO with plantar flexion stop (AFO-PS) and (b) AFO with plantar flexion resistance (oil damper; AFO-OD).

Gait was measured using a three-dimensional motion analysis system (10 VICON MX cameras and 6 AMTI force plates). A total of 34 reflective markers were attached to patients at various landmarks. Markers were placed on the thorax (spinous processes of the 7th cervical and 10th thoracic vertebrae, the xiphoid process of the sternum, and the jugular notch where the clavicles meet the sternum) and on the pelvis (both anterior superior iliac spines and the posterior superior iliac spines). Markers were also placed on the upper limbs (both shoulders, elbows, and wrists) and lower limbs (both hips, thighs, knees, shanks, ankles, heels, and metatarsophalangeal (MP) joints). Additional markers were placed on the medial aspect of the knee, ankle, and MP joints to allow accurate calculation of the joint center. Marker trajectories and force plate data were sampled at a frequency of 100 Hz. Patients wore shoes that were prepared for the experiment (V-step; Pacific Supply), which were used in usual gait training for stroke patients. The shoes were used in gait without an AFO as well as for the nonparetic foot in gait with an AFO. The use of canes was allowed if necessary and was consistent in the two conditions for each patient.

Shod gait at the patients’ selected speed without an AFO was measured. As mentioned above, the first measurement was done as patients began walking 10 m with supervision. Measurements were repeated until four paretic limb steps on the force plates had been obtained. Patients were then divided into two groups: AFO-PS and AFO-OD. Each patient participated in 1 h of physiotherapist-led gait training every day for 2 weeks, using the specified type of AFO. Gait training was performed identically between the groups. After the completion of training, gait with the specified type of AFO was measured using the same procedure described above.

Data processing

Marker trajectories and force plate data were low-pass filtered by a second-order Butterworth filter with cutoffs of 6 and 18 Hz, respectively. The link segment model consisted of 12 segments: thorax and pelvis and both upper arms, forearms, thighs, shanks, and feet. The center of gravity (COG) for each segment of the link segment model were calculated using anthropometric data. Progressive COG velocity was calculated by differentiating the displacement of the combined COG. Joint kinematics and kinetics were calculated using an inverse dynamic model. Step length was normalized by body height, and ground reaction force and joint moment were normalized by body weight. Joint angles, joint moments, and ankle power were calculated for the paretic limb. The peak values in each gait phase and the change in each phase were calculated. Because most patients did not exhibit heel rise of the paretic limb in single-stance phase, the stance phase was subdivided into loading response, single stance, and pre-swing. These phases were divided using the vertical component of the ground reaction force. In total, the 37 gait parameters shown in Tables 2 to 4 were calculated. The lateral obliquity and rotation of the pelvis and thorax were also calculated. All calculations were performed using Visual 3D software version 5 (C-Motion Inc.).

Statistical analysis

Gait parameters were measured and averaged for at least three gait cycles in each condition (without an AFO before training and with an AFO after training). Normality of the data was assessed by the Shapiro–Wilk test. A two-way analysis of variance (ANOVA) was performed for normally distributed data, with paired factors (condition, with and without) and an unpaired factor (type of AFO). If no interaction was found, the main effects of the two factors were considered. In cases of interaction, comparison was made between conditions in each AFO group using one-way ANOVA. Data without normal distribution were subjected to the Wilcoxon t-test to compare the different conditions and Man–Whitney U-test for the type of AFO. Statistical significance was set at p values of less than 0.05. SPSS version 24 for Windows was used for all statistical analysis.

Results

A total of 20 patients were analyzed in each group (Figure 2). There were no significant differences between the groups in age, body height, body weight, days after onset, or gait velocity without an AFO, as shown in Table 1.

Figure 2.

Consolidated Standard of Reporting Trials (CONSORT) flow chart.

Table 1.

Patient profiles.

	AFO-PS ( n = 20)	AFO-OD ( n = 20)
Sex	Male: 18; Female: 2	Male: 18; Female: 2
Age (years)	59.2 (SD = 9.8)	60.2 (SD = 12.3)	ns
Body height (cm)	169.0 (SD = 6.0)	165.5 (SD = 7.8)	ns
Body weight (kg)	65.1 (SD = 10.9)	63.9 (SD = 9.8)	ns
Diagnosis	Cerebral hemorrhage: 12; cerebral infarction: 8	Cerebral hemorrhage:10; cerebral infarction: 10
Paretic side	Right: 12; Left: 8	Right: 12; Left: 8
Days since onset	78.4 (SD = 47.3)	68.9 (SD = 24.0)	ns
Brunnstrom stage of lower extremities	II: 2; III: 6; IV: 5; V: 6; VI: 1	II: 1; III: 8; IV: 3; V: 7; VI: 1
Velocity without an AFO (m/s)	0.27 (SD = 0.19)	0.25 (SD = 0.12)	ns

AFO-PS: AFO with plantar flexion stop; AFO-OD: AFO with oil damper; SD: Standard deviation.

The normality of all parameters, except the loading response time and center of pressure (COP) progression in single stance, was confirmed. Temporal and spatial factors, ground reaction forces, and COP progression results are shown in Table 2. Joint kinematics and kinetics are shown in Table 3, and pelvic and thoracic tilt angles are shown in Table 4. Data for lateral obliquity and rotation of the pelvis and thorax are not shown because there were neither interactions nor differences between conditions and groups.

Table 2.

Temporal and spatial factors and ground reaction forces.

Parameters		AFO-PS		AFO-OD		Interaction	Main effect
Parameters		Without	With	Without	With	Interaction	With and without	AFO type
Temporal and distance factors	Velocity (m/s)	0.27 (0.19)	0.42 (0.25)	0.25 (0.12)	0.37 (0.17)	0.654	0.006*	0.824
	Paretic to nonparetic (m/BH)	0.11 (0.09)	0.19 (0.09)	0.15 (0.07)	0.19 (0.06)	0.491	<0.001**	0.288
	Nonparetic to paretic (m/BH)	0.19 (0.07)	0.22 (0.07)	0.19 (0.06)	0.22 (0.06)	0.987	<0.001**	0.624
	Cycle time (s)	2.18 (0.56)	1.86 (0.54)	2.46 (0.60)	1.98 (0.52)	0.223	<0.001**	0.232
	Loading response time (s)^a	0.42 (0.31)	0.31 (0.25)	0.57 (0.41)	0.32 (0.21)		<0.001**	0.450
	Single-stance time (s)	0.37 (0.11)	0.39 (0.10)	0.44 (0.15)	0.47 (0.12)	0.676	0.209	0.051
	Pre-swing time (s)	0.72 (0.38)	0.47 (0.31)	073 (0.29)	0.46 (0.31)	0.751	<0.001**	0.956
	Swing time (s)	0.63 (0.14)	0.63 (0.15)	0.68 (0.17)	0.68 (0.16)	0.900	0.874	0.304
Ground reaction forces	Max posterior component (N/BW)	−0.080 (0.035)	−0.019 (0.045)	−0.078 (0.045)	−0.099 (0.047)	0.367	0.007**	0.842
Ground reaction forces	Max anterior component (N/BW)	0.040 (0.024)	0.047 (0.038)	0.044 (0.026)	0.052 (0.022)	0.968	0.066	0.577
COP progression	Progression in loading response (m)	0.084 (0.023)	0.092 (0.027)	0.090 (0.024)	0.104 (0.024)	0.548	0.050	0.096
COP progression	Progression in single stance (m)^a	0.019 (0.025)	0.030 (0.045)	0.018 (0.019)	0.036 (0.032)		<0.001**	0.707

AFO-PS: AFO with plantar flexion stop; AFO-OD: AFO with oil damper; BH: body height in meters; BW: body weight in kilograms; COP: center of pressure.

Parametric data: mean (standard deviation).

Nonparametric data: median (interquartile range).

Nonparametric analysis.

p < 0.05; **p < 0.01.

Table 3.

Joint kinematics and kinetics.

Parameters		AFO-PS		AFO-OD		Interaction	Main effect
Parameters		Without	With	Without	With	Interaction	With and without	AFO type
Ankle joint angle	Initial contact (°)	−9.18 (8.91)	−6.19 (6.96)	−6.17 (6.51)	−1.67 (4.44)	0.822	<0.001**	0.052
	Change in loading response (°)	−1.64 (1.90)	−1.11 (1.09)	−2.57 (2.58)	−3.28 (2.53)	0.401	<0.001**	0.091
	Maximum dorsiflexion in single stance (°)	1.29 (9.16)	4.26 (6.24)	4.86 (6.60)	6.71 (5.56)	0.521	0.008**	0.149
	Maximum plantar flexion in pre-swing (°)	−4.06 (8.22)	−2.99 (5.67)	−1.43 (8.00)	1.65 (5.17)	0.367	0.066	0.149
	Maximum dorsiflexion in swing (°)	−4.77 (8.29)	−3.64 (5.67)	−1.80 (7.90)	1.07 (4.92)	0.941	0.271	0.155
Ankle joint moment and power	Maximum dorsiflexion in loading response (Nm/BW)	−0.02 (0.03)	−0.04 (0.06)	−0.01 (0.04)	−0.05 (0.03)	0.229	<0.001**	0.712
	Maximum plantar flexion in stance (Nm/BW)	0.61 (0.28)	0.90 (0.36)	0.66 (0.27)	0.90 (0.37)	0.366	<0.001**	0.747
	Maximum power in stance (W)	0.04 (0.10)	0.09 (0.12)	0.06 (0.11)	0.08 (0.15)	0.414	0.086	0.817
Knee joint angle	Initial contact (°)	9.57 (5.13)	11.65 (5.81)	6.55 (7.44)	8.01 (5.56)	0.683	0.023*	0.066
	Maximum extension in single stance (°)	6.84 (8.52)	7.72 (11.01)	1.01 (12.11)	1.05 (11.01)	0.701	0.671	0.060
	Maximum flexion in swing (°)	41.99 (11.59)	42.21 (10.82)	37.30 (14.90)	35.55 (14.02)	0.272	0.396	0.164
Knee joint moment	Maximum extension in loading response (Nm/BW)	0.10 (0.15)	0.24 (0.18)	0.19 (0.18)	0.21 (0.16)	0.496	0.098	0.733
Knee joint moment	Maximum flexion in single stance (Nm/BW)	−0.13 (0.27)	−0.19 (0.26)	−0.28 (0.39)	−0.35 (0.32)	0.976	0.087	0.108
Hip joint angle	Initial contact (°)	18.38 (5.51)	22.27 (6.99)	18.27 (7.16)	17.81 (7.84)	0.075	0.157	0.222
Hip joint angle	Maximum extension in single stance (°)	8.67 (9.58)	8.28 (14.36)	6.97 (11.09)	2.68 (10.11)	0.136	0.075	0.287
Hip joint moment	Maximum extension in loading response (Nm/BW)	0.35 (0.18)	0.48 (0.29)	0.36 (0.16)	0.36 (0.21)	0.139	0.090	0.328
Hip joint moment	Maximum flexion in single stance (Nm/BW)	−0.04 (0.34)	−0.12 (0.43)	−0.27 (0.25)	−0.20 (0.31)	0.472	0.006	0.646

AFO-PS: AFO with plantar flexion stop; AFO-OD: AFO with oil damper; BW: Body weight in kilograms; AFO: ankle–foot orthosis.

Data are represented as mean (standard deviation).

Joint angle: positive values indicate flexion and dorsiflexion.

Joint moment (internal): positive values indicate extension and plantar flexion.

p < 0.05; **p < 0.01.

Table 4.

Pelvic and thoracic tilt angles.

Parameters		AFO-PS		AFO-OD		Interaction	Main effect		One-way ANOVA
		Without	With	Without	With		With and without	AFO type	AFO-PS	AFO-OD
		Without	With	Without	With		With and without	AFO type	With and without	With and without
Pelvic tilt	Initial contact (°)	−3.02 (5.02)	−6.47 (7.04)	−5.64 (6.43)	−4.96 (6.48)	0.046*			0.021*	0.642
	Nonparetic foot off (°)	−7.40 (4.46)	−9.55 (7.80)	−10.10 (6.15)	−7.91 (6.90)	0.041*			0.156	0.146
	Nonparetic initial contact (°)	−8.99 (4.70)	−11.68 (7.20)	−11.70 (6.39)	−10.62 (6.45)	0.066	0.425	0.631
	Foot off (°)	−7.16 (5.33)	−10.57 (8.10)	−11.00 (6.35)	−10.41 (7.13)	0.063	0.184	0.333
Thoracic tilt	Initial contact (°)	−3.11 (5.68)	−3.47 (6.61)	−3.91 (5.81)	−1.09 (6.59)	0.022*			0.724	0.005**
	Nonparetic foot off (°)	−5.49 (6.16)	−4.72 (7.38)	−6.82 (6.52)	−2.31 (6.85)	0.022*			0.386	<0.001**
	Nonparetic initial contact (°)	−7.89 (6.58)	−7.34 (7.09)	−9.24 (7.37)	−5.45 (6.88)	0.025*			0.581	0.001**
	Foot off (°)	−6.06 (6.17)	−6.24 (7.44)	−8.27 (7.44)	−5.51 (7.71)	0.031*			0.825	0.008**

AFO-PS: AFO with plantar flexion stop; AFO-OD: AFO with oil damper; AFO: ankle–foot orthosis; ANOVA: analysis of variance.

p < 0.05; **p < 0.01.

Data are represented as mean (standard deviation).

Tilt angle: negative values indicate forward tilt.

As shown in Tables 2 and 3, no interaction was found in temporal and spatial factors, ground reaction forces, and joint kinematics and kinetics. A main effect that showed the difference between conditions, with and without an AFO, was found for many parameters. Regarding the temporal and spatial factors, the velocity, step lengths, posterior component of the ground reaction forces, and COP progression in single stance were increased in the gait with an AFO. Cycle time, loading response time, and pre-swing time were decreased in the gait with an AFO. In terms of ankle joint kinematics and kinetics, the dorsiflexion angle at initial contact, plantar flexion change in loading response, maximum dorsiflexion in single stance, maximum dorsiflexion moment in loading response, and maximum plantar flexion moment in stance were increased in the gait with an AFO. Knee joint flexion at initial contact was larger in the gait with an AFO. There was no significant difference between the AFO-PS and AFO-OD groups regarding these parameters.

Interactions were found in pelvic and thoracic tilt angles (Table 4). One-way ANOVA was performed for parameters, which showed the interaction to compare the conditions in each AFO group. In AFO-PS group, the forward inclination of the pelvis at initial contact was increased when the patients walked with the AFO compared with the shod gait without an AFO; no difference was found in the AFO-OD group. Concerning the thoracic tilt angle, the forward inclinations at initial contact, nonparetic foot off, nonparetic initial contact, and foot off were decreased when the patients walked with the AFO-OD compared with the shod gait without an AFO; no difference was found in the AFO-PS group.

Figure 3 shows the average and standard deviation of tilt angle of the pelvis for each group. The horizontal axis shows the percent gait cycle starting at initial contact of the paretic limb, and the vertical axis shows the tilt angle with forward tilt as negative. The waveforms are similar in shape, but forward tilt was increased when patients walked with the AFO-PS (Figure 3(a)). In the AFO-OD group, no difference was found between conditions (Figure 3(b)). Figure 4 shows the average thoracic tilt angle in the same way. Forward tilt was reduced throughout the gait cycle when patients walked with the AFO-OD (Figure 4(b)), but no difference was found between conditions in the AFO-PS group (Figure 4(a)).

Figure 3.

Average and standard deviation of pelvic tilt angles in one gait cycle Negative values indicate forward tilt: (a) AFO-PS and (b) AFO-OD.

Figure 4.

Average and standard deviation of thoracic tilt angles in one gait cycle Negative values indicate forward tilt: (a) AFO-PS and (b) AFO-OD.

In terms of the participants’ perception, many patients felt it was easier to walk with an AFO than without an AFO in both groups. Some patients in the AFO-PS group complained about hindrance to the ankle joint movement during gait; however, no patients in the AFO-OD group had such complaints.

Discussion

Many differences between gait with and without an AFO were observed within the two AFO groups (AFO-PS and AFO-OD). Because the subjects in this study were stroke patients in the subacute phase, these changes were caused by the patients’ recovery process, the effect of training, and the effect of the AFO. The increases in velocity, step length, COP progression, and ankle and knee joint angles and moments observed in this study were similar to those observed in previous studies comparing gait with and without an AFO.^1–3

The focus of this study was to investigate the effect of AFO function on the ankle, knee, and hip joints during the gait of stroke patients in subacute phase. Our results showed no interaction between the two AFO groups in joint kinematics and kinetics. Although not significant (p = 0.075), hip flexion angle at initial contact was increased from 18.4° ± 5.5° without an AFO to 22.3° ± 7.0° with an AFO in the AFO-PS group, but it decreased from 18.3° ± 7.2° to 17.8° ± 7.8° in the AFO-OD group.

A previous study that compared the ankle joint angle between AFO-PS and AFO-OD groups showed that the ankle joint started dorsiflexion immediately after initial contact in the AFO-PS group.²³ However, the ankle joint gradually moved to plantar flexion in the AFO-OD group. Generally, increased dorsiflexion induces flexion of the knee and hip joints due to a kinematic chain. However, there were no significant differences between groups in parameters regarding the ankle, knee, and hip joints in this study. This could be attributed to the variety of patients’ gait patterns. In previous studies, the gait of patients in the subacute phase was categorized into certain patterns, such as extension thrust, buckling knee, and stiff knee.^24,25 In these studies, the key parameter for categorization was knee joint movement. Another study on the effect of plantar flexion resistance of the AFO demonstrated that the subjects were limited to the stroke patients who showed genu recurvatum.¹⁶ Conversely, gait pattern was not considered as inclusion criteria in our study, and so, significant differences were not easily detected in the ankle, knee, and hip joints.

Differences between the two AFO groups were found in the movement of the pelvis and thorax. Interactions were found in the tilt angles of these segments. In the AFO-PS group, the pelvis was inclined forward to a greater degree at initial contact compared with the shod gait without an AFO. In contrast, in the AFO-OD group, the thoracic tilt angle was reduced throughout the stance phase compared with the shod gait without an AFO. Although there were no significant differences in the lower extremities between the two AFO groups, the observed differences in the tilt angles of the pelvis and thorax may have been caused by different alignment during initial contact and loading response of the paretic limb. The AFO-PS induces flexed alignment of the lower limb as well as forward tilt of the pelvis. In contrast, the AFO with plantar flexion resistance promotes gradual movement to plantar flexion in loading response, assisted by the oil damper. This induces relatively extended alignment of the lower limb without causing forward tilt of the pelvis, resulting in an upright thoracic posture. The inclined posture of the pelvis and the thorax is a known feature of the gait of stroke patients.²⁶ Previous studies comparing gait with and without AFOs focused on ankle and knee joint kinematics and kinetics,² and few studies have investigated the effect of different kinds of AFOs on the pelvis.²⁷ The results of this study show that AFOs may have an indirect effect on alignment of the pelvis and thorax during the gait of stroke patients in the subacute phase. These findings suggest that the AFO with plantar flexion resistance facilitates better alignment of the upper body and pelvis. This type of AFO could be beneficial for patients who have malalignment of the upper body and pelvis during gait.

There are some limitations to this study. First, the duration of AFO use was 2 weeks in this study. Although this was necessary for ethical reasons, it did not provide sufficient time to show the full effects of AFO function. Second, as the data obtained in this study were measured at a rehabilitation center, the universality of the results has not been demonstrated. The patients in this study showed a variety of gait patterns. Finally, the participants were stroke patients in the subacute phase. Future studies should clarify whether similar results are obtained for stroke patients in the chronic phase.

Conclusion

The gait of 40 stroke patients in the subacute phase was measured before and after 2 weeks of gait training using either an AFO with plantar flexion stop or an AFO with plantar flexion resistance. Significant differences between the two AFO groups were found in tilt angles of the pelvis and thorax; compared with the shod gait without an AFO, the pelvis showed forward tilt when patients walked with an AFO with plantar flexion stop and the thorax showed reduced forward tilt when patients walked with an AFO with plantar flexion resistance. The plantar flexion resistance function of the AFO affected the alignment of the upper body and the pelvis during the gait of stroke patients in the subacute phase.

Footnotes

Acknowledgements

The authors thank the patients who participated in this study. The authors also thank the physiotherapists who performed the gait training and assisted with the gait measurement.

Author contribution

All authors contributed equally in the preparation of this manuscript.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by JSPS KAKENHI Grant Number 26350630.

References

Ferreira

Neto

Grecco

et al . Effect of ankle-foot orthosis on gait velocity and cadence of stroke patients: a systematic review. J Phys Ther Sci 2013; 25: 1503–1508.

Tyson

Sadeghi-Demneh

Nester

CL.

A systematic review and meta-analysis of the effect of an ankle-foot orthosis on gait biomechanics after stroke. Clin Rehabil 2013; 27: 879–891.

Tyson

Kent

RM.

Effects of an ankle-foot orthosis on balance and walking after stroke: a systematic review and pooled meta-analysis. Arch Phys Med Rehabil 2013; 94: 1377–1385.

Leung

Moseley

Impact of ankle-foot orthoses on gait and leg muscle activity in adults with hemiplegia: systematic literature review. Physiotherapy 2003; 89: 39–55.

Lehmann

Condon

Price

et al . Gait abnormalities in hemiplegia: their correction by ankle-foot orthoses. Arch Phys Med Rehabil 1987; 68: 763–771.

Slijper

Danielsson

Willlen

Ambulatory function and perception of confidence in persons with stroke with a custom-made hinged versus a standard ankle foot orthosis. Rehabil Res Pract 2012; 2012: 206495.

Gok

Kucukdeveci

Altinkaynak

et al . Effects of ankle-foot orthoses on hemiparetic gait. Clin Rehabil 2003; 17: 137–139.

Mulroy

Eberly

Gronely

et al . Effect of AFO design on walking after stroke: impact of ankle plantar flexion contracture. Prosthet Orthot Int 2010; 24: 277–292.

Nolan

Yarossi

Preservation of the first rocker is related to increases in gait speed in individuals with hemiplegia and AFO. Clin Biomech 2010; 26: 655–660.

10.

Yamamoto

Hagiwara

Mizobe

et al . Gait improvement of hemiplegic patients using an ankle-foot orthosis with assistance of heel rocker function. Prosthet Orthot Int 2009; 33: 307–323.

11.

Perry

Burnfield

JM.

Gait analysis, normal and pathological function. 2nd ed. Thorofare, NJ: SLACK, 2010: 51–81.

12.

Yamamoto

Tomokiyo

Yasui

et al . Effects of plantar flexion resistive moment generated by an ankle-foot orthosis with an oil damper on the gait of stroke patients: a pilot study. Prosthet Orthot Int 2013; 37: 212–221.

13.

Kobayashi

Leung

Akazawa

et al . The effect of varying the plantar flexion resistance of an ankle-foot orthosis on knee joint kinematics in patients with stroke. Gait Posture 2013; 37: 457–459.

14.

Singer

Kobayashi

Lincoln

et al . The effect of ankle-foot orthosis plantarflexion stiffness on ankle and knee joint kinematics and kinetics during first and second rockers of gait in individuals with stroke. Clin Biomech 2014; 29: 1077–1080.

15.

Kobayashi

Singer

Orendurff

et al . The effect of changing plantarflexion resistive moment of an articulated ankle-foot orthosis on ankle and knee joint angles and moments while walking in patients post stroke. Clin Biomech 2015; 30: 775–780.

16.

Kobayashi

Orendurff

Singer

et al . Reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle-foot orthosis in individuals post-stroke. Clin Biomech 2016; 35: 81–85.

17.

Yamamoto

Fuchi

Yasui

Change of rocker function in the gait of stroke patients using an ankle foot orthosis with an oil damper: immediate changes and the short-term effects. Prosthet Orthot Int Prosth 2011; 35: 350–359.

18.

Haruna

Sugihara

Kon

et al . Change in the mechanical energy of the body center of mass in hemiplegic gait after continuous use of a plantar flexion resistive ankle-foot-orthosis. J Phys Ther Sci; 2013; 25(11): 1437–1443.

19.

Richards

Olney

Hemiparetic gait following stroke. Part II: recovery and physical therapy. Gait Posture 1996; 4: 149–162.

20.

Richards

Malouin

Dumas

et al . Gait velocity as an outcome measure of locomotion after stroke. In: Oatis

(ed.) Gait analysis: Theory and applications. St. Louis, MI: Mosby, 1995; 355–364.

21.

Bohannon

Wimith

MB.

Interrater reliability of a modified Ashworth scale of muscle spasticity. Phys. Ther 1987; 67: 206–207.

22.

Yamamoto

Hagiwara

Mizobe

et al . Development of an ankle-foot orthosis with an oil damper. Prosthet Orthot Int Prosth 2005; 29: 209–219.

23.

Ohata

Yasui

Tsuboyama

et al . Effects of an ankle-foot orthosis with oil damper on muscle activity in adults after stroke. Gait Posture 2011; 33: 102–107.

24.

De Quervain

Simon

Leurgans

et al . Gait pattern in the early recovery period after stroke. J Bone and Joint 1996; 78(10): 1506–1514.

25.

Mulroy

Gronley

Weiss

et al . Use of cluster analysis for gait pattern classification of patients in the early and late recovery phases following stroke. Gait Posture 2003; 18: 114–125.

26.

Bohannon

RW.

Gait after stroke. Orthopaed Phys Ther Clin North Am 2001; 10: 151–171.

27.

Desloovere

Molenaers

Gestel

et al . How can push-off be preserved during use of an ankle foot orthosis in children with hemiplegia? A prospective controlled study. Gait Posture 2006; 24: 142–151.