Original articles
Effects of anterior ankle-foot orthoses and modified custom-made hinged orthoses on the walking of patients with stroke
2023 Volume 23 Issue 1 Pages 8-17
Details
2023 Volume 23 Issue 1 Pages 8-17
Background and research objective: Hemiparesis is one of the most common types of damage resulting from stroke. Stroke affects the daily life of patients and reduces their ability to walk. In Taiwan, patients with stroke are mainly presented with two choices of ankle-foot orthoses (AFOs): hinged posterior AFOs (hinged P-AFOs) and anterior AFOs (A-AFOs). In this study, we designed a modified AFO (M-AFO) that enables flexible motion in the metatarsophalangeal joints. We conducted a gait analysis and a 6-minute walking test (6MWT) to determine how the A-AFO and M-AFO improve gait. Method: A total of 14 patients with hemiparesis were included and randomly assigned into two groups. The first group wore the A-AFO for 1 month first and then visited our laboratory for gait analysis and 6MWT. They then wore the M-AFO for 1 month and visited our laboratory for further tests. The second group wore the aforementioned orthoses but in reversed order. The data analyzed included the stride width, step length, stride length, velocity, cadence, and 6MWT outcomes. Results: Significant differences were observed in stride width, step length, stride length, velocity, and 6MWT outcomes (P < 0.05). The 6MWT results indicated that patients wearing the M-AFO walked longer than those wearing the A-AFO (P < 0.01). Conclusion: According to the analyzed data of the M-AFO and A-AFO obtained using a gait analysis and 6MWT, patients with stroke are advised to use our proposed M-AFO for rehabilitation, particularly for the adjustment of gait. Clinical significance: Our results may serve as a reference for patients with stroke seeking to use lower-limb orthoses for training purposes.
According to the Ministry of Health and Welfare of Taiwan, 50 out of every 100,000 individuals died from cerebrovascular diseases in 2020, with approximately 30,000 new diagnoses of stroke on an annual basis [1]. Hemiparesis is one of the most common types of damage caused by stroke, which may interfere with activities of daily living and gait patterns [2]. Patients with hemiparesis due to a stroke frequently experience additional complications, including pes equinus, pes varus, knee hyperextension, knee flexion contractures, and spasticities. Regaining the ability to walk is thus one of the primary objectives for patients with stroke. Most patients with stroke regain their ability to walk through rehabilitation, which they undergo for 3-6 months after the onset of stroke [3, 4]. However, when patients with hemiparesis due to a stroke undergo training for walking, they experience difficulty controlling their lower limbs, and they develop an abnormal gait pattern and walk much slower than healthy individuals [5, 6]. Because these patients lack control over their legs, ankle-foot orthoses (AFOs) are used during the early stages to aid in their gait training. Currently, more than 10 types of AFOs are available for patients with stroke to choose from. These AFOs provide such patients with optimal support and protection for their lower limbs. They also improve their walking speed and stability when walking on stairs. AFOs also reduce the amount of energy expended during walking [7, 21-23], and they decrease ankle plantarflexion, improve knee flexion, and allow toe extension. In addition to providing support and stabilizing ankle joints during the stance phase, AFOs provide stability during the swing phase by mitigating the effect of spasticity during the swing phase, thereby improving the level of stability during this phase. Moreover, AFOs prevent the toes from touching the ground during the swing phase, thereby facilitating walking [8, 24, 25].
Depending on the support type, AFOs are divided into anterior AFOs (A-AFOs) and posterior AFOs (P-AFOs), and P-AFOs are further subdivided into AFOs with and without hinge joints. Currently in Taiwan, A-AFOs and hinged P-AFOs are the most commonly used AFO types [9]. A-AFOs allow for metatarsophalangeal (MTP) joint extension, but they limit ankle dorsiflexion. Therefore, during the stance phase, they do not provide ankle dorsiflexion angles, thereby resulting in a compensatory gait pattern. By contrast, hinged P-AFOs provide a wide range of motion for the ankle, but they do not provide correction angles for the MTP joints. They also do not allow the patients to adjust their MTP joints during the propulsion phase. During the midstance phase, A-AFO wearers have smaller ankle plantarflexion and dorsiflexion angles compared with those of P-AFO wearers. However, compared with A-AFO wearers, P-AFO wearers have higher stability and larger ankle dorsiflexion angles, indicating that P-AFOs allow patients to have a more natural gait pattern [2, 10]. In Taiwan, 90% of patients with stroke have A-AFOs manufactured for them while they are at the hospital. A-AFOs are made of low-temperature thermoplastics. They are simple and rapid to manufacture and are relatively cheap. They are also covered by Taiwan’s National Health Insurance program and are eligible for subsidies.
In Japan, a company called Yamagata prostheses institute co., Ltd researched and developed an AFO that allowed for a wide range of motion in the MTP joints and improved the ability of patients with stroke-induced hemiparesis to walk [26]. However, no pertinent gait analyses have been performed. Therefore, in this study, we designed a modified AFO (M-AFO) that facilitates flexible motion of the MTP joints and then conducted a gait analysis and 6-minute walking test (6MWT) to determine the effect of an A-AFO commonly used in Taiwan and the proposed M-AFO on gait.
Participants
A total of 14 participants with hemiparesis were included in the study. The inclusion criteria were as follows: (1) being 30-65 years of age, (2) receiving a diagnosis of stroke-induced hemiparesis, (3) having been diagnosed with stroke for more than 6 months, (4) being able to walk independently on 10 meters flat surface, and (5) having an adequate foot skin condition on the affected side, with no broken skin or pain. The exclusion criteria were as follows: (1) having any medical gait-related problems other than stroke or (2) having brain damage that may affect language abilities (e.g., aphasia) or expression. All participants signed an informed consent form. The participants were randomly assigned into two groups. The first group wore the A-AFO for 1 month first and then visited our laboratory for gait analysis and 6MWT. They then wore the M-AFO for 1 month and visited our laboratory for further tests. The second group wore the aforementioned orthoses but in reversed order. This study was approved by the medical ethics committee and institutional review board of Kuang Tien General Hospital (KTGH11030).
All of the M-AFOs were manufactured by the same individual using polypropylene. The joint angle of the orthosis provided 90° MTP joint flexion control and an unrestrained dorsiflexion angle. The M-AFO also supported the foot arch in the middle. At the MTP joints, it provided toe extension angles (Fig. 1A).
The A-AFO was made of a low-temperature thermoplastic material. The ingredients were placed in hot water at 60-80 °C for softening and reshaping. To prepare the A-AFO, the participant was asked to sit on a chair, bend their knees at 90°, and place their ankle in a neutral position. The material was then directly placed on the participant’s foot [10] (Fig. 1B).
The participants were asked to walk as fast as they could back and forth in a corridor that was 30 meters long and 3 meters wide [4, 6]. Participants can use a quad cane if required for safety reasons. The distance they walked within 6 minutes was then measured. A 10-minute break was set after the first measurement. It could be extended until the participants feel comfortable before taking the second measurement. The second measurement was done. A higher score was recorded.
We used the Brunnstrom stage to evaluate and record the motor recovery and ankle muscle tonus of the participants. Before the gait analysis, all participants practiced walking with and without orthoses. Before walking, they were asked to stand still for 5 sec for all cameras to record markers in order to facilitate the analysis of their initial anatomical position. Every participant walking with and without an orthosis was then examined. The participants were instructed to walk at a speed of their choice with the A-AFO or the M-AFO. Their walking sequence with the A-AFO or M-AFO was arbitrary. They were allowed to take breaks any time in the tests. Therefore, to reduce the measurement errors of gait analysis, we collected data from three successful tests and averaged the results. We then used the mean for statistical analysis.
The data analyzed included the stride width, step length, stride length, velocity, cadence, and 6MWT outcomes. The data on joint angles included the minimum and maximum angles of the hip, knee, and ankle joints during the stance and swing phases. The data on the ground reaction force included the minimum and maximum values on the x-axis (front and back axis) and the two peak values on the z-axis (up and down axis).
All statistical analyses were performed using SPSS 12 (IBM. NY. USA). Wilcoxon’s signed rank-sum test was used to compare the two lower-limb orthoses. Statistical significance was set at P < 0.05.
Table 1 lists the data of the 14 participants, namely their age, sex, height, weight, time since the onset of stroke, and the affected side. Comparison of the M-AFO and A-AFO revealed significant differences in stride width, step length, stride length, velocity, and 6MWT outcomes (P < 0.05) but not in cadence (Table 2). The stride width of the M-AFO group was greater than that of the A-AFO group (P < 0.05). The step length and stride length of the M-AFO group were greater than those of the A-AFO group (P < 0.01). The walking speed of the M-AFO group was greater than that of the A-AFO group (P < 0.01). According to the 6MWT results, the M-AFO group walked longer than the A-AFO group (P < 0.01).
During the stance phase, the maximum angle of the ankle joint of the M-AFO group was significantly larger than that of the A-AFO group (P < 0.05). However, the minimum and maximum angles of the hip and knee joints did not exhibit significant differences (Table 3). During the swing phase, no significant differences were observed in the minimum and maximum angles of the hip, knee, and ankle joints (Table 4). Regarding the ground reaction force, no significant differences were observed in the minimum and maximum values on the x-axis or in the maximum values of the first and second peaks on the z-axis (Table 5).
According to a previous study, as a result of hemiparesis, patients with stroke may exhibit supination while walking [11]. Supination causes such patients to shift their load from the heel to the lateral side of the foot bottom, leading to their loss of balance and compromising their safety in walking. They may also experience claw toes, resulting in a difficulty walking [7, 12]. AFOs are used to mitigate the likelihood of pes varus and claw toes. They control the ankle joint to allow patients with stroke to walk normally. Chen et al. [10] compared the cases of patients using A-AFOs, patients using P-AFOs, and patients not using AFOs at all. From the A-AFO and P-AFO kinematics, they discovered that the use of AFOs can help patients with stroke control their ankle joints and mitigate the likelihood of their feet turning inward during the stance and swing phases.
In a previous study comparing A-AFOs and P-AFOs [27], no significant differences in ankle joint angles were observed. However, in the present study, we discovered that when the M-AFO was used, the ankle dorsiflexion angle significantly exceeded that of the A-AFO. Providing a range of motion at the MTP joint allowed the ankle joint to have larger dorsiflexion angles. Therefore, from the midstance phase to the heel-off phase, patients with stroke exhibited decreased compensatory gait.
Our statistical analysis results indicated that the M-AFO significantly increased velocity, step length, and stride length. These results are similar to those of previous studies [4, 13, 17, 18]. This is presumably because, compared with the A-AFO, the M-AFO provided a wider range of motion at the ankle joint. Our statistical analysis results also revealed that, during the stance phase, compared with the A-AFO, the M-AFO provided a wider range of motion for the ankle joints. With this increased range of motion, the patients experienced larger dorsiflexion angles at the ankle joints between the midstance phase and heel-off phase. This allowed them to move forward and to have decreased compensatory gait.
Yeung et al. [14, 24, 25] investigated the effects of lower-limb orthoses on ankle joint dorsiflexion in patients with stroke. They reported that these orthoses facilitated the patients’ ascent and descent of stairs. In the present study, orthoses provided a range of motion for the MTP joints, allowing the patients’ feet to have a propelling effect during the midstance and toe-off phases. However, the statistical analyses did not reveal considerable differences in the ground reaction force on the z-axis. Nonetheless, for the ground reaction force on the x-axis, the maximum value for the M-AFO was greater than that for the A-AFO. Although this difference was not statistically significant, it was still useful for the patients.
Patients with stroke frequently experience tension, resulting in a hyperextended knee joint and compensatory gait at the knee joint [15]. In previous studies [14, 16, 17], orthoses were used to achieve ankle joint dorsiflexion and prevent the knee joint from hyperextension during the stance phase while allowing for a wide range of motion in the knee joint during the swing phase. In the present study, no significant differences in the minimum and maximum angles of the knee joint were observed during the stance or swing phase. However, the minimum and maximum knee joint angles achieved by the M-AFO during both phases were greater than those achieved by the A-AFO, indicating that, during the stance phase, compared with the A-AFO, the M-AFO allowed for increased flexion in the knee joint from the midstance to the toe-off phase. In addition, compared with the A-AFO, the M-AFO prevented the knees from hyperextension during the midstance phase and allowed for a wider range of motion in the knee joint during the swing phase. It also prevented the toes from coming into contact with the ground and facilitated walking.
According to previous studies in which 6MWTs were conducted on patients with stroke [4, 8], compared with patients without orthoses, patients using lower-limb orthoses covered a longer distance in 6 minutes. Patricia et al. [8] proposed that the 6MWT can be used as an indicator of patients’ recovery from stroke. Our statistical analysis results indicated that, compared with the A-AFO group, the M-AFO group covered a longer distance during the 6MWT. The M-AFO group also walked significantly faster, indicating that providing a range of motion at the ankle joint allowed patients with stroke to walk faster. The M-AFO allowed the ankle joint to move [18-20], thereby improving the stability and propulsion ability of the patients during the stance phase as well as reducing their compensatory gait.
The relationship between brace effectiveness and Brunnstrom Stage is of interest. This time, we only showed the average data for each orthosis, but when we analyzed the walking speed of individual subjects, the young subject at stage 5 and had a long period after onset showed the fastest walking speed. However, the slowest speed was not observed in Stage 3, the lowest stage, in subjects who were older and had a short post-onset period. The stage is related to the superiority or inferiority of walking in general. Still, the Stage represents only the stage of recovery, and it seems that the superiority or inferiority of walking is determined by various factors of the individual subject. It seemed difficult to find a general trend in an experiment with a small number of subjects like this time. This is an issue for the future.
In this study, quantitative data were used to compare the M-AFO and A-AFO. The data were analyzed using gait analysis system and the 6MWT within the context of stroke rehabilitation. The results indicated that the M-AFO is useful in the rehabilitation of patients with stroke, especially in regaining their physical ability to walk.
