Orthotic gait rehabilitation in patients with spinal cord injury (SCI) has several advantages from the physiological and psychological point of view.1–3 Body-weight-supported treadmill training strategies have been introduced as a promising approach to improve gait in SCI patients.4 This system is basically used in a clinical environment as it is difficult to use this system in homes. An orthotic system (e.g., powered gait orthoses, hybrid orthoses, and mechanical orthoses) is another system that is used in the orthotic gait rehabilitation in SCI patients.5
The most simple and traditional approach to enable standing and walking in patients with SCI is the use of purely mechanical orthoses.1 Among the mechanical orthoses, the isocentric reciprocating gait orthosis (IRGO) has been reported to be the most effective orthosis in improving walking parameter and energy consumption.1–3 The design of the IRGO was originally based on the concept of facilitating a reciprocal gait pattern for paraplegic patients and is therefore commonly prescribed for SCI patients for walking and standing. It consists of two knee-ankle-foot orthoses (KAFOs) connected laterally to a superstructure supporting the trunk and includes the hip joints that can be locked into extension once the patient is standing.2 The hip joints restrict hip motion in the frontal plane and permit reciprocal hip motion in the sagittal plane. A number of studies have reported the positive effect of this type of orthosis on paraplegic patients.6–8
Winchester et al.7 demonstrated that the energy costs of walking at comfortable self-selected speeds were lower with the IRGO as compared with the reciprocating gait orthosis (RGO). A study by Leung et al.,8 which compared between the two types of orthoses in terms of energy consumption by SCI patients, found that the patients utilized 8 weeks of gait training with the orthoses. In another comparison study between the walkabout orthosis (WO) and an IRGO, Harvey et al.6 reported that the speed of walking was faster and energy consumption was lower when using the IRGO compared with the WO in 10 complete SCI patients, following 8 weeks of gait training. Arazpour et al.9 compared a powered gait orthosis, an IRGO, and a hip KAFO (HKAFO) in SCI patients and demonstrated that the speed of walking, the distance walked, and the Physiological Cost Index (PCI) improved with both the powered gait orthosis and IRGO as compared with the HKAFO. However, the patients received only 6 weeks of gait training to accommodate to the orthosis. Massucci et al.10 reported that a walking speed of 16 m/min could be achieved after 6 to 8 weeks of walking training with an advanced RGO, but the energy cost of walking increased during the training period.
Different modalities of gait rehabilitation associated with physical therapy are used in the domain of neurological rehabilitation (e.g., manually assisted overground training and manually assisted treadmill training, both with or without body weight support).11–13 It was demonstrated that incomplete SCI subjects improved their ability to walk on a treadmill and/or overground.12 On the other hand, orthotic gait training is defined as a critical component of walking rehabilitation in paraplegic patients.14 Arazpour et al.,15 in an evaluation of orthotic gait training with powered hip orthosis (PHO) in four SCI patients, showed that gait kinematics and temporal-spatial parameters were improved after a period of gait training with a PHO. Functional ambulation was reported as the main outcome measure for the SCI patients after orthotic gait rehabilitation. Walking ability, with or without suitable assistive devices, to sufficiently and safely carry out of activities of daily living (ADLs) was reported to be the definition of functional ability.16 Based on this definition, the speed of walking, endurance, independence grade, and the need for assistive devices were demonstrated as the predicators of functional ambulation. Because clinicians can readily assess the efficacy of experimental interventions, these types of measures are essential outcomes in rehabilitation research studies. Previous studies have not yet reported the longitudinal evaluation of the efficiency of gait training in these parameters. To the best of our knowledge, only Samadian et al.,17 in their evaluation of orthotic gait rehabilitation with IRGO on six SCI patients, have reported the progression of walking speed while subjects underwent regular gait training. They also reported that PCI decreased over time. Therefore, the aim of this study is to provide evidence supporting the progression of walking speed and functional ambulation over 12 weeks of orthotic gait rehabilitation using IRGO in patients with SCI.
MATERIAL AND METHODS
Twelve subjects with spinal cord lesions at T6 to T12 levels participated in the study (Table 1). The paraplegic patients were characterized by their traumatic SCI of scale B according to the American Spinal Injury Association score. They had no previous experience of walking with an orthosis. The subjects had no evidence of cardiovascular or pulmonary diseases, contractures, severe spasticity, obesity, or asymmetric hip positions. Informed consent for the study was obtained from the paraplegic subjects. The performance of this study was approved by the ethics committee of the University of Social Welfare and Rehabilitation Sciences.
Gait Speed and Endurance
The principal outcome variables include walking speed and walking distance. Via two different clinical tests, the 10-m walk test (10MWT) the 6-m walk test (6MWT) in one day, the speed of walking and walking distance were analyzed in this study by one researcher. Walking speed was measured with the 10MWT18 and walking distance was measured with the 6-minute walk test.19
Walking speed in 10 m via using 10MWT was recorded during 10-m sections of continuous walking while wearing the orthosis by use of a stopwatch. This test demonstrated a documented measure of the time required for the subject to traverse 10 m at his/her self-selected walking speed. The 6MWT demonstrated the distance that a subject can walk in 6 minutes. It is one of the most valid and highly sensitive gait evaluation measures in SCI patients. The reliability coefficient of this test was reported to be 0.7520 In the evaluation of the patients with these two tests, each individual was permitted to use the necessary orthoses and assistive devices. They were asked to walk in a straight line at a comfortable pace.
The subjects received information about the performance of the IRGO and how to use RGOs after the orthosis was constructed. The baseline analyses were performed one day after orthotic preparation.
Functional Independence Measure (FIM) locomotor subscale and the Walking Index for Spinal Cord Injury II (WISCI II) were used to measure locomotive ability.
For the FIM locomotor subscale score, the primary mode of locomotion in the community (walking/wheelchair) was determined for each patient at the beginning and end of the training by assigning an ordinal rating (1–7) to the amount of physical assistance or use of assistive devices and braces required. We also recorded the FIM locomotor subscale score for overground ambulation on a weekly basis, regardless of the primary mode of locomotion used. This measure provided an estimate of improvement in overground ambulation. Interrater reliability of FIM mobility subscale scores for walking/wheelchair use has been estimated to be fair to poor (Spearman coefficient, 0.60; κ statistic, 0.40) in a diverse population of patients with SCI.21,22
The WISCI II evaluation scale was used to determine the use of assistive devices, lower-limb bracing, and physical assistance during overground walking.23 The WISCI II assigns ordinal scores for locomotor performance, with a score of 0 to 20 (0 = a person is unable to ambulate with assistance, 20 = person can ambulate at least 10 m without assistive devices, bracing, or physical assistance). Hence, less dependence on assistive devices while walking yields higher scores.
ORTHOTIC GAIT TRAINING
The patients received 12 weeks of gait training after the construction of the orthosis that comprised five sessions per week for a 2-hour period with the orthosis. The gait training program also included passive stretching of the lower limbs, upper-limb strengthening, and balance training with the orthosis while standing and walking. Approximately 1 hour of the 2-hour gait training session was typically taken up by the walking and standing activities. Once each subject achieved a satisfactory level of standing ability (i.e., safe and stable), walking using a reciprocating-gait pattern with the IRGO was achieved. The technique of gait training with the IRGO was taught to the participants as illustrated in Table 2. All gait training was applied by a physiotherapist with expertise in walking and standing of paraplegic patients. Safety precautions (e.g., spotting and overhead tether) were used to ensure safety and confidence while learning to use an orthosis.
The IRGO used in this study consisted of two KAFOs, which were connected with a pelvic band. In this orthosis, the bilateral hip joints were connected via a reciprocal link. The function of the reciprocal link caused flexion of the orthotic hip joint on one side and extension of the hip joint on the other side and vice versa. In this study, the ankle-foot orthoses incorporated in the IRGO were custom molded using plaster of Paris casts of the lower limbs for each volunteer. Figure 1 shows the IRGO used in this study. The volunteer subjects received the IRGO for 4 weeks after the initial evaluation. The patients were asked to contact the rehabilitation team if they felt any discomfort while wearing the orthosis.
Normality of data was approved by using the Kolmogorov-Smirnov method. The primary outcome measures were evaluated using a repeated measure analysis of variance. Tukey honest significant difference post hoc tests were used to identify specific differences between the two groups. Spearman rank-correlation coefficient was used to examine the relationship between the level of lesion and mentioned variables. SPSS 16 (SPSS Inc, Chicago, IL, USA) was used for data analysis. The significant level was α = 0.05. Patients used themselves as a control by considering their initial stage before the use of orthosis.
COMPARISON OF WALKING SPEED, ENDURANCE, AND LOCOMOTOR DISABILITY BETWEEN 4, 8, AND 12 WEEKS AFTER GAIT TRAINING WITH AN ISOCENTRIC RECIPROCATING GAIT ORTHOSIS
Table 3 shows an increase in the FIM scale of walking when using the IRGO. In the intragroup comparison, FIM in the paraplegia patients increased when having received gait training with an IRGO between baseline and 4 weeks, and this continued to increase up to 12 weeks after IRGO wearing.
In addition, an increase in the WISCI II scale of walking was observed when using the IRGO, as shown in Table 3. In the intragroup comparison, WISCI in the paraplegia patients increased when they received gait training with an IRGO between baseline and 4 weeks, and this continued to increase up to 12 weeks after IRGO wearing. There was no statistically significant difference between 4 and 8 weeks of gait training in this parameter (p = 0.136).
All subjects used the reciprocal gait pattern for each test. The subjects able to walk at the average walking speed for RGO users without any training with preliminary education in walking with an IRGO for the baseline measurement. However, there were significant improvements in walking speed between the baseline and 4 weeks after orthotic gait training (p ≤ 0.01), 8 weeks after orthotic gait training (p ≤ 0.01), and also 12 weeks after walking with the orthosis (p ≤ 0.01). There was no statistically significant difference between 8 and 12 weeks of gait training in this parameter (p = 0.097).
A significant difference was observed in the 6MWT after 4, 8, and 12 weeks of orthotic gait training compared with the baseline (Table 3). In the intragroup comparison, 6MWT in the paraplegia patients increased when they received gait training with an IRGO between baseline and 4 weeks, and this continued to increase up to 12 weeks after IRGO wearing (Table 3).
COMPARISON OF INJURY LEVEL REGARDING GAIT PARAMETERS
The results of this study demonstrated that patients with a higher level of injury have lower speeds of walking and less walking distance as compared with patients with a lower level of SCI. Table 4 demonstrates the alteration to evaluated parameters of SCI patients regard to level of injury in this study.
Table 5 summarizes the Spearman rank-correlation coefficient (rs) between the injured level and each parameter obtained in this study. By evaluating the Spearman rank-correlation coefficient, mean speed of walking and level of injury in baseline (rs = 0.775; p < 0.01) and FIM-locomotor and level of injury in baseline (rs = 0.675; p < 0.05) showed a strong relevance to the injury level.
The benefit of mechanical orthoses in rehabilitation has many implications for SCI patients.2 The advantages of using these types of interventions include the ability to stand and walk, which in turn influences community mobility and social participation.1 Based on high energy consumption and the problem of experiencing dysfunction while standing and walking, the functional ability has been found to decrease and the problems in performing ADLs increase in case of SCI patients.3 The energy consumption by IRGO has been found to be lower than that in other mechanical orthoses.2 The use of orthotic gait training is considered to be a rehabilitation strategy. To the best of our knowledge, the present study is the first longitudinal study to examine their ability for promoting functional ambulation in SCI patients.
The concept of wearing IRGO is using reciprocal gait pattern for ambulation. This point was advised in the gait training program. All of the subjects used a reciprocal gait pattern for the 10MWT and 6MWT, respectively. Reciprocal gait pattern was evaluated for the WISCI and FIM tests. Our findings based on the 10MWT showed that longitudinal gait training with an IRGO allowed individuals with SCI to ambulate at speed of 0.31 m/s after completion of the training program. The walking speed based on our results from the 6MWT was different compared with the rate of this parameter in 10MWT. In using 10MWT, the subjects used a self-selected speed; therefore, the value of the speed of walking was similar to the normal rate of this parameter in wearing a mechanical orthosis. In the analysis of the patients in using 6MWT, walking distance was considered. It seems patients have tried for this purpose; therefore, they may have made a strong effort while walking with the orthosis in this test. The maximum speed of walking was reported to be 0.3 m/s by using mechanical orthoses and wearing commercial powered exoskeletons such as the ReWalk (0.55 m/s). A threshold of walking speed was reported at 0.44 and 0.49 m/s for limited community ambulation with SCI to cross an intersection.24 The reported walking speed by using mechanical orthoses may be with or without any expert's supervision indoors.25 In this study, the mean improvements in the speed of walking of SCI patients while walking with IRGO were demonstrated as 0.24, 0.27, 0.30, and 0.31 m/s, respectively; all these were proved to be statistically significant.1 These improvements continued throughout the training period of the study. A study reported orthotic gait training of SCI patients with PHO in which the hip joint kinematics and spatiotemporal parameters showed improvement after a walking training period.15 In another study, an improvement in walking speed through the training time was reported in six SCI patients.17 Compared with previous studies that used mechanical orthoses such as IRGO, the mean of speed of walking has been reported to be 0.34 and 0.28 m/s after 8 and 12 weeks of training period, respecitvely.6,17 While using powered orthoses, the mean of this parameter was reported to be 0.17 m/s by wearing Rewalk (Ekso Bionics, Richmond, CA, USA), 0.14 m/s by using Ekso™ Bionics exoskeleton, 0.31 via walking with Indego, 0.16 m/s with the wearable power-assist locomotor, and 0.4 m/s when wearing a PHO.26
The same as SCI subjects in a previous study in this field, the patients with SCI faced difficulties (e.g., fatigue, fear of falling, stepping) in the initial stage of the orthotic gait training program.27 Fatigue and fear of falling can be substantially reduced with training. In addition, stepping can be increased with education and ambulation learning. At the completion of training, they showed improvement in walking independently and ADL performance. It seems that after appropriate gait training with orthoses and after gaining the ability to walk and stand with an orthosis, patients with SCI may use less energy during orthotic ambulation than do those without orthotic gait training. Samadian et al.17 suggested that improvements in energy expenditure may be caused by increased lower-limb muscle stimulation, but further research is required to verify this hypothesis. A high relationship between lower-limb muscle activity and the needed energy of ambulation with an orthosis was reported in a previous study.28 Although this point has not fallen into the evaluation criteria of this study, the improvement of energy consumption has been marked after 12 weeks of orthotic gait training with a mechanical orthosis.17
In our study, gait training with IRGO was seen to increase functional ambulation compared with baseline. This increase continued throughout the training period. In addition, the increase in the mentioned study parameters may have occurred for several reasons while performing orthotic gait training, such as improved trunk position and decreased upper-limb joint loading with orthotic use. However, the efficiency of orthotic gait training on improving upper-limb loading and trunk position was not evaluated in this study. Because the upper limb and trunk movement above the paralysis level is required to provide ambulation in the SCI patients,29,30 future studies in this field will prove to be beneficial in this regard.
The level and severity of the injury and the age of SCI patients are also defined as important factors of affected parameters in providing the ability to walk with orthoses. Patients with a low level of injury showed better improvement results in all the mentioned parameters during the whole gait training time. It was demonstrated that SCI patients with a lower-level injury had better gait parameters compared with SCI patients with upper (higher) levels of injury.31
The training approach varied significantly across studies on SCI patients.26 Different training programs have been reported for both powered orthoses and mechanical orthoses. Some studies involved a shorter training period,32–37 whereas a set training protocol lasting over several weeks to months was performed in other studies.26 In some studies, the participants were progressed to training on different surfaces including sidewalk, grass, or stairs.38–40 In one such study, the SCI patients wearing powered gait orthoses were allowed to walk on a treadmill as part of the training protocol to improve users' confidence and speed.41 Arazpour et al.9 included upper-limb strengthening and lower-limb stretching as part of the walking intervention protocol in the evaluation of the powered gait orthoses in SCI patients. In another study, the longitudinal gait training effect of the wearing the IRGO in 12 weeks was reported in the SCI patients.17 In this study, a programmed gait training approach was used that was a combination of all gait training programs. Unfortunately, there were no studies that evaluated how the differences in training programs affected the walking ability outcomes in the SCI patients. Further research will be beneficial in this field.
LIMITATION OF THIS STUDY
The evaluation of orthotic gait training on patients' quality of life and electromyography of the lower-limb muscles were not assessed in this study, and the design of a further study will be beneficial in this field. Comparison between gait training with IRGO and commercial powered exoskeletons (e.g., Rewalk, HAL) and other mechanical orthoses (e.g., HKAFOs, medial linkage orthoses, and HGOs) can be considered in future studies in this field. Because IRGO with physical therapy was evaluated and there is no control group, it is difficult to understand if the effectiveness was caused by physical therapy or using IRGO. Future study with a control group will be beneficial in this field.
This study demonstrated that SCI patients showed an increase in walking functional ambulation ability during a longitudinal period of orthotic gait training with an IRGO. In conclusion, wearing an IRGO associated with gait training can provide individuals with thoracic-level SCI the ability to walk faster.
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