(1)
Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstraße 200a, 69118 Heidelberg, Germany
(2)
Department for Orthopedic Surgery and Traumatology, Heidelberg University Hospital, Schlierbacher Landstraße 200a, 69118 Heidelberg, Germany
Abstract
Treatment of acute spinal cord injury (SCI) comprises two major therapeutic concepts, which aim for either restoration or compensation. Both strategies aim to reach the highest level of quality of life, mainly reflected by independence and participation in social activities. Restoration in this context means to recover sensorimotor function, which has been impaired or abolished by an incomplete spinal cord or cauda equine lesion. Therefore, only in patients with spared sensorimotor axon pathways restorative strategies can be successfully employed. In contrast, compensation means to replace irreversibly lost function through an alternative strategy, e.g., wheelchair mobility will substitute for the mobility achieved through walking. A number of excellent textbooks describe compensatory strategies in SCI rehabilitation in detail. This chapter will focus on therapies to promote recovery of walking function.
In order to choose appropriate rehabilitative treatment strategies, a precise definition of realistic goals to be achieved in each patient is of utmost importance. Respective goals can only be determined once neurological dysfunction and functional deficits are properly assessed. Therefore, effective goal setting approaches and internationally accepted neurological and functional assessment schemes will be described. Accordingly, task specific therapies (e.g., body weight supported treadmill training), supporting therapies (conventional physical therapy targeting muscle strength, balance and trunk stability, functional electrical stimulation) and orthotic devices including wearable exoskeletons will be described.
23.1 Planning and Goal Setting
The rehabilitation process of spinal cord injury (SCI) patients includes multiple phases and a variety of interventions with the aim to maximize independence and to participate in the social environment. This can be accomplished by means of compensation or restoration. Compensation in this context means that the rehabilitative therapy aims to change movement strategies, which will allow to substitute for the function that has been lost after SCI. For example, wheelchair mobility is the main compensatory strategy to replace lost walking ability in motor complete SCI. In contrast, restorative strategies in the rehabilitative context train incomplete SCI patients to regain lost motor function. As an example, locomotor training – from body-weight-supported treadmill training to unsupported overground walking – can be employed to restore locomotor function after sensorimotor incomplete SCI.
Due to the increasing number of incomplete SCI patients – mainly ASIA Impairment Scale (AIS)-C/AIS-D – a shift in the therapeutic focus has become apparent [1]. Compensatory therapies become more frequently supplemented by approaches to restore lost or improve impaired motor functions. In this chapter we focus on the recovery of standing and walking function. Irrespective of restorative or compensatory rehabilitative strategies, appropriate patient goals should be defined based on the International Classification of Functioning, Disability and Health (ICF). Accordingly, short- and medium-term goals correspond to the level of activity and function, whereas long-term goals reflect the patient’s life goals and participation [2]. Short- and medium-term goals can change daily, weekly, or monthly and should be achievable within the time frame of the rehabilitation process. Respective goals should be oriented toward the long-term objectives and at the same time need to be adapted to the current situation during the rehabilitation process. The goals, especially those concerning participation, should be decided by the patient and not by the treatment team. Here, the fact of defining goals does not mean that they must always or can always be achieved. It is more a case of formulating long-term prospects that will probably have to be revised or modified during the treatment.
Clinical Case
A female patient with incomplete paraparesis (T8; AIS-C) wants to return back into her apartment, which can only be reached via a few stairs. As a consequence, the restorative concept aims to train getting up from the wheelchair and climbing stairs independently, thus defining short- and medium-term goals. In case climbing stairs through a restorative strategy cannot be achieved, assistive devices for stair climbing will be considered, and relatives will be trained to support the patient in this task.
At the beginning of the inpatient rehabilitation treatment, the multidisciplinary professional team should meet to define the current status of the patient and to establish short- and medium-term goals considering the patient’s perspective. To standardize this process, a goal setting scheme should include the neurological, musculoskeletal, nutritional and functional status of the patient (Tables 23.1 and 23.2 ). For each of these items, the goals and the appropriate rehabilitative approach will be checked. Patient status, goals, and approaches will be reviewed weekly and adjusted if necessary. The focus on restorative versus compensatory strategies is based on the SCI severity and the level of neurological injury according to the International Standards for Neurological Classification of SCI (ISNCSCI). In addition, the patient’s age and relevant comorbidities including disease prognosis (e.g., spinal cord compression due to metastatic cancer) will affect the goal setting process [3]. Among other things, increasing age is associated with a lower level of functional outcome despite comparable changes in the neurological status between different age groups [4].
Table 23.1
Goal setting: according to the current neurological status, a realistic goal and the appropriate therapeutic intervention can be chosen (goal setting scheme – Heidelberg University Hospital).
Current status | Goal | Therapeutic intervention |
|---|---|---|
☐ Sensory complete ☐ Sensory incomplete ☐ Motor complete ☐ Motor incomplete | ☐ Compensation ☐ Sensorimotor restoration | ☐ Wheelchair skills ☐ Wheelchair sports ☐ Body-weight-supported treadmill (with/without exoskeleton), overground walking ☐ Functional training upper extremities ☐ Turning, sitting, transfer ☐ Activities of daily living ☐ Functional electrical stimulation ☐ Muscle strengthening – not task specific ☐ Testing/prescription assistive devices ☐ Instruction/training of caregivers ☐ Other PT measures (bench, mat training) |
Table 23.2
Goal setting: according to the neurological complications, a realistic goal and the appropriate therapeutic intervention can be chosen (goal setting scheme – Heidelberg University Hospital)
Current Status | Goal | Therapeutic intervention |
|---|---|---|
☐ Spasticity, myoclonus ☐ (neuropathic) pain ☐ Autonomic dysreflexia (AD) ☐ Others (sweating) | ☐ Reduction of spasticity ☐ Reduction of pain ☐ Reduction of autonomic dysreflexia (AD) | ☐ Identification of spasticity, pain, AD trigger ☐ FES, treadmill, tilt table ☐ Other PT interventions (proper positioning, Kinesio tape, lymphatic drainage, massage, TENS) ☐ Antispastic medication ☐ Analgesic medication |
Therapies for individuals with motor complete SCI (AIS-A/AIS-B) mainly focus on compensatory interventions. Restorative strategies have been shown to elicit neurological improvement such as improved electromyographic (EMG) activity in paretic muscles. However, it is not possible to achieve clinically meaningful functional improvement in severely affected SCI patients with such interventions [5]. In motor incomplete SCI patients (AIS-C/AIS-D), we aim for restoration, unless an unfavorable underlying disease prognosis, serious concomitant disease condition(s), or advanced age contradicts. Since the outcome cannot be exactly foreseen in incomplete SCI patients due to a considerable variability in respect to functional and neurological recovery, it is advised to add compensatory rehab strategies to the overall program. Since the length of stay in SCI centers has been dramatically cut down over the years, there is no room for starting compensatory approaches once restorative treatments have failed. The prime goal should always be to discharge an independent patient – be it through restoration of walking and standing or through independent wheelchair mobility. Vice versa, if a rather complete SCI individual gains sensorimotor function over time, restorative concepts will be added to the compensation-centered rehab approach. Of course, therapists should be aware of the fact that patients with prime focus on compensatory elements sometimes do not understand and support such a concept. They expect that functions can be restored irrespective of injury severity, especially when they extrapolate from more incomplete SCI patients, who are challenged with body-weight-supported treadmill training instead of training of wheelchair skills. Such conflicts require careful information of the patient’s conditions and explanations, why rehab goals are important in order to obtain independence in everyday life. Nevertheless, despite appropriate goal setting, one of the main difficulties of reintegration reported by patients with SCI during the first year following discharge from hospital relate to mobility aspects such as transfer problems [6].
23.2 Assessments
A goal-oriented rehabilitation treatment plan requires to obtain objective information about the current patient status. This involves evaluating the physical and functional status as well as recording aspects, which may affect the rehabilitation process, e.g., presence and severity of pain, preexisting medical and functional conditions, and current medication. Respective assessments will facilitate the initial goal setting process and over time serve as a basis to adjust therapeutic goals and related interventions accordingly.
The relevant assessments can be divided into (1) testing of the function and structure of the body (e.g., examination of sensory and motor function, manual muscle testing, testing the range of motion, and movement control examinations) and (2) functional outcome measures (e.g., Walking Index for Spinal Cord Injury, Timed Up and Go, etc.).
23.2.1 Neurological Function
The ISNCSCI is developed and published by the American Spinal Injury Association (ASIA), currently on its sixth edition. It is the worldwide accepted tool to determine motor and sensory impairments in SCI individuals in standardized fashion. The examination contains sensory and motor components to determine the neurological level and to classify the severity of the injury according to the AIS. The neurological level of injury (NLI) refers to the most caudal segments with intact sensory and motor function. The severity of the injury is graded in five steps ranging from A (complete SCI) to E (normal sensory and motor function) [9–11]:
A | Complete. No sensory or motor function is preserved in the sacral segments S4–S5 |
B | Sensory incomplete. Sensory but not motor function is preserved below the neurological level and includes the sacral segments S4–S5, and no motor function is preserved more than three levels below the motor level on either side of the body |
C | Motor incomplete. Motor function is preserved below the neurological level, and more than half of key muscle functions below the single neurological level of injury have a muscle grade less than 3 |
D | Motor incomplete. Motor function is preserved below the neurological level, and at least half of key muscle functions below the NLI have a muscle grade of 3 or more |
E | Normal. If sensation and motor function as tested with the ISNCSCI are graded as normal in all segments |
The sensory examination requires the testing of a key point in each of the 28 dermatomes (from C2–S4–5) bilaterally for light touch and pinprick. All sensations are scored with three points: 0 = sensation is absent; 1 = sensation is impaired or partial appreciation, including hyperesthesia; and 2 = sensation is normal. Besides deep anal pressure is examined and should be graded as being present or absent.
Within the motor examination, ten key muscles of the myotomes C5–T1 (C5, elbow flexors; C6, wrist extensors; C7, elbow extensors; C8, finger flexors; T1, small finger abductors) and L2–S1 (L2, hip flexors; L3, knee extensors; L4, ankle dorsiflexors; L5, long toe extensors; S1, ankle plantar flexors) are assessed on both sides with manual muscle testing. Furthermore, the voluntary anal contraction is assessed and scored as absent or present [9–11].
23.2.1.1 Manual Muscle Testing
Manual muscle testing (MMT) according to Janda is based on a subjective assessment, in spite of its well-defined scale of strength levels. Furthermore, the test only allows the state of the muscles at a specific instant to be evaluated and does not allow the assessment of muscle fatigue. Yet muscle testing according to Janda is a firmly established part of routine clinical practice and an important component of physical examinations. The approach identifies six fundamental stages (Table 23.3) [12]:
Table 23.3
Manual muscle testing
Level of strength | Description |
|---|---|
5 | Corresponds to a muscle with normal strength, which is able to negotiate intensive resistance within the full range of movement. Important: this does not mean that the muscle is without pathological findings when performing all functions (e.g., fatigue) |
4 | The muscle tested can perform a movement to the full range and negotiate medium resistance (corresponds to approx. 75 % of normal muscle strength) |
3 | The muscle tested can perform a movement to the full range against gravity. Additional resistance cannot be negotiated (corresponds to approx. 50 % of normal muscle strength) |
2 | The muscle tested can perform a movement to the full range but only when gravity is eliminated since the tested extremity cannot hold its own weight (corresponds to approx. 25 % of normal muscle strength) |
1 | The muscle tested can be contracted, but the tested extremity cannot be moved (corresponds to approx. 10 % of normal muscle strength) |
0 | No signs of arbitrary muscle contraction |
In the examination concerning the lower extremities, in addition to the key muscles of the myotomes L2–S1 of the ISNCSCI examination (as mentioned above), the hip extensors, the hip abductors and adductor, and the knee flexors should be examined.
23.2.1.2 Range of Motion
The range of motion (ROM) of individual joints and the spine has a considerable influence on the patient’s function and the level of independence after SCI. For example, limited spine movement following extensive spinal fusion surgery can be a cause for patient’s inability to carry out intermittent catheterization independently. The neutral zero method is used to describe the maximum possible passive and active range of motion of a joint in all possible planes of movement based on a standard initial position. First, the angle of maximum movement away from the body is given, then the 0-position (zero), and finally the angle of maximum movement toward the body. If motion is limited, the zero (0-position) will not appear in the middle but on the side upon which there is a deficit [13]. Taking the upper ankle joint as an example, unlimited range of motion would mean plantar flexion/dorsal extension: 50°/0/30°. In the case of pes equinus, the following result may be obtained, depending on the range of motion: 50/20°/0°. In this case, the neutral position cannot be achieved, and there remains a residual flexion of 30° between 20° and 50° plantar flexion. The lack of a neutral position in the upper ankle joint may prohibit a proper sitting position in the wheelchair causing secondary strain to the ischii. Worst case, sitting in the wheelchair may become impossible.
23.2.1.3 Spasticity Measure
The Modified Ashworth Scale is frequently used for grading spasticity in routine clinical practice. It can be easily performed and does not require any equipment. The velocity-dependent response of muscles to passive stretching is rated in a six-point nominal scale [14]: 0 = no increase in muscle tone; 1 = slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is moved in flexion or extension; 1+ = slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM; 2 = more marked increase in muscle tone through most of the ROM, but affected part(s) easily moved; 3 = considerable increase in muscle tone, passive movement difficult; and 4 = affected part(s) rigid in flexion or extension.
Of note, the Ashworth Scale represents a subjective assessment and only checks single-joint resistance to passive ROM at a specific point in time. The interaction of muscle chains, the spasm frequency, or possible spasticity triggers are not examined. Even the impact of spasticity on function cannot be assessed.
The Penn Spasm Frequency Scale (PSFS) represents a patient-reported outcome measure. However, its reliability has yet to be confirmed. The patient completes a self-assessment questionnaire reporting spasm frequency (0 = no spasms, 1 = spasms induced only by stimulation, 2 = infrequent spontaneous spasms occurring less than once per hour, 3 = spontaneous spasms occurring more than once per hour, 4 = spontaneous spasms occurring more than ten times per hour) and intensity (1 = mild, 2 = moderate, 3 = severe) [15]. More details on spasticity measures can be found in chapter 13).
23.2.2 Functional Outcome Measures
23.2.2.1 Spinal Cord Independence Measure
The Spinal Cord Independence Measure, version III (SCIM III), specifically designed for individuals with SCI, is a comprehensive disability scale [16, 17]. The assessment reflects aspects of self-care management, medical conditions, and mobility. The tool is grouped into three areas of function and takes approx. 30 min to complete, ideally by observing the patient (Table 23.4 ). The test does not require any particular equipment and can be incorporated into clinical routine.
Table 23.4
Main parts of SCIM III
Self-care |
|---|
Feeding: cutting, opening containers, pouring, bringing food to mouth, holding cup with fluid (0–3 points) |
Bathing: soaping, washing, drying body and head, manipulating water tap: upper body (0–3 points), lower body (0–3 points) |
Dressing: clothes, shoes, permanent orthoses: dressing, wearing, undressing: upper body (0–4 points), lower body (0–4 points) |
Grooming: washing hands and face, brushing teeth, combing hair, shaving, applying makeup (0–3 points) |
Respiration and sphincter management |
Sphincter management – bladder (0–15 points) |
Sphincter management – bowel (0–10 points) |
Use of toilet: perineal hygiene, adjustment of clothes before/after, use of napkins or diapers (0–5 points) |
Respiration (0–10 points) |
Mobility (room and toilet)/mobility (indoors and outdoors, on even surface) |
Mobility in bed and action to prevent pressure sores (0–6 points) |
Transfers: bed to wheelchair: locking wheelchair, lifting footrests, removing and adjusting arm rests, transferring, lifting feet (0–2 points) |
Transfers: wheelchair to toilet to tub: if uses toilet wheelchair: transfers to and from; if uses regular wheelchair: locking wheelchair, lifting footrests, removing and adjusting armrests, transferring, lifting feet (0–2 points) |
Mobility: indoors (0–8 points), moderate distances (10–100 m) (0–8 points), outdoors (more than 100 m) (0–8 points) |
Stair management (0–3 points) |
Transfers: wheelchair to car, approaching car, locking wheelchair, removing arm- and footrests, transferring to and from car, bringing wheelchair into and out of car (0–2 points) |
Transfers: ground to wheelchair (0–1 points) |
The first section involves the item of self-care – feeding, bathing, dressing, and grooming – with a total score of 20 points. The second section refers to activities of respiration, bladder sphincter management, and bowel sphincter management and collects a maximum of 40 points. The third section reflects all aspects of mobility with 40 points total to be achieved. Thus, a maximum of 100 points can be reached from all sub-items, whereas increasing number of points reflects improved independence [18].
23.2.2.2 Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI)
The gait assessment is SCI specific and easy to assess and evaluates three components of walking: gait pattern (Table 23.5 ) with a maximum of 20 points, the use of assistive devices (e.g., cane, walker, orthosis) with a maximum of 14 points, and walking modalities such as speed, frequency, and distance with five possible points. Higher scores denote a higher level of walking ability, although the subscores should not be combined to make an overall score. The measurement is a combination of observation and the patient’s self-report [18, 19].
Table 23.5
Observational gait analysis part of the SCI-FAI
Parameter | Description |
|---|---|
Weight shift | Weight shift to stance limb or weight shift absent or only onto assistive device |
Step width | Swing foot clears stance foot on limb advancement or stance foot obstructs swing foot on limb advancement |
Final foot placement does not obstruct swing limb or final foot placement obstructs swing limb | |
Step rhythm (relative time needed to advance swing limb) | At heel strike of stance limb, the swing limb: begins to advance in <1 s or requires 1–3 s to begin advancing or requires >3 s to begin advancing |
Step height | Toe clears floor throughout swing phase or toe drags at initiation of swing phase only or toe drags throughout swing phase |
Foot contact | Heel contacts floor before forefoot or forefoot or foot flat first contact with floor |
Step length | Swing heel placed forward of stance toe or swing toe placed forward of stance toe or swing toe placed rearward of stance toe |
23.2.2.3 Walking Index for Spinal Cord Injury
The Walking Index for Spinal Cord Injury (WISCI) is a functional scale for clinical use and for research to evaluate improvements in ambulation. In the second version (WISCI II) with two additional levels, the walking capability is rated from 0 to 20 based on the individual’s dependence on assistive devices, braces, and personal assistance. The examiner observes the patient, who walks 10 m, and rates the level, which is considered to be safe. Level 0 describes that the client is unable to stand and/or participate in assisted walking. At level 1 the patient ambulates in parallel bars, with braces and physical assistance of two persons, less than 10 m. At the highest level 20, the patient ambulates with no devices, no braces, and no physical assistance over a distance of at least 10 m [18, 20]. The use of the WISCI is limited in assessing individuals with only minor walking impairment due to a ceiling effect. Walking endurance is not reflected in this score [21].
23.2.2.4 6-Minute Walk Test
The 6-minute walk test (6 MWT) measures the distance a patient can walk on a flat surface as quickly as possible in 6 min. The patient may stop and rest (but not sit) during the test, and the use of auxiliary equipment is also permitted. Along with the ability to walk, endurance and cardiopulmonary capacity are also evaluated, among other things. The test was originally designed for patients with respiratory impairments. In the case of incomplete SCI patients, the 6 MWT is particularly suitable for individuals with minor impairments, in order to record further improvement [18, 22, 23].
23.2.2.5 Timed Up and Go
The Timed Up and Go (TUG) is a timed walking test, which was originally developed to assess the sense of balance in elderly individuals and the resulting danger of falling. The TUG records the time (in seconds) that the patient needs to rise from a chair, to walk three meters, to turn around when they get to the 3-m line, and to walk back and sit back down on the chair [24]. If it takes the patient more than 30 s to accomplish the task, they will normally require help for transfers and going up stairs, and they are not able to go outside alone. Use of auxiliary equipment is permitted. The test is easy to carry out and can be used to assess walking ability, even in SCI patients, although no standard value has been established for the SCI population at this time [18].
23.2.2.6 10-Meter Walk
For the 10-meter walk test (10 MWT), the patient must be able to walk at least 14 m as this is the total distance to be covered in this test. It measures the time in seconds that the patient needs to walk 10 m, from meter 2 to meter 12 (“flying start”). Assistive devices may be used [25]. However, the use of auxiliary devices is not taken into account when scoring, and no statement can be made about endurance due to the walking distance only being 10 m. The test can be used in a clinical context and to evaluate walking ability in individuals with SCI in clinical studies [18, 24].
23.2.2.7 Berg Balance Scale
Initially developed for elderly persons, the Berg Balance Scale (BBS) is now also used for stroke and SCI patients as well as those suffering from multiple sclerosis. It comprises a total of 14 items, which are each assessed on a 5-point scale. The overall number of points ranges from 0 points (severely impaired balance) to 56 points (excellent balance). The categories are as follows:
- 1.
Sitting to standing
- 2.
Standing unsupported
- 3.
Sitting with back unsupported but feet supported on floor
- 4.
Standing to sitting
- 5.
Transfers from an armless chair to a chair with arms
- 6.
Standing unsupported with eyes closed
- 7.
Standing unsupported with feet together
- 8.
Reaching forward with outstretched arms
- 9.
Picking up an object from the floor
- 10.
Turning to look behind over left and right shoulders
- 11.
Turning 360°
- 12.
Placing alternate feet on step or stool while standing unsupported
- 13.
Standing unsupported one foot in front
- 14.
Standing on one leg
23.3 Therapeutic Strategies for Lower Extremity Rehabilitation
23.3.1 Compensation Toward Functional Independence
This chapter focuses on strategies to promote recovery of walking function. For compensatory strategies, it is referred to respective textbooks. The main goal of rehabilitation is to achieve the maximum level of independence, which can be achieved to a varying extent depending on the lesion severity, level of injury, and concomitant comorbidities. It is acknowledged that for individuals with severe/high-level SCI, compensatory strategies and assistive technology represent the only alternative to regain functional independence.
If it is not possible to restore the standing and walking function sufficiently for everyday life or if this is not yet foreseeable within the scope of the initial treatment, the rehabilitation team has to encourage the patient to work toward functional independence. Patients with severe motor impairments, who converted from walking at discharge to the wheelchair within 1 year after injury, experienced poor quality-of-life factors with high levels of depression and pain scores [27].
Individual rehabilitation plans have to be constantly adapted to the current level of therapy and supplemented by compensatory elements. It is essential to practice also wheelchair mobility, transfer skills, and activities of daily living and adapt the necessary devices. Just one example which is choosing the appropriate wheelchair is an individual decision and depends on a great many factors. Using a mechanical wheelchair requires sufficient functioning of the upper extremities, the trunk muscles, and corresponding cardiopulmonary capacity. If these conditions are not met, use of an electrical device/electrical wheelchair must be examined. Further criteria include, among other things, the sitting position, primary use (indoor, outdoor, for sport), and the patient’s demands on the wheelchair. For detailed descriptions and instructions of compensatory strategies/skills, see, for example, Somers and Harvey [28, 29].
23.3.2 Restoration of Locomotor Function
The main goal in lower extremity functional restoration is recovery of – ideally unaided – walking function. Depending on the degree of spared functions, the therapy can also address the ability to get up and stand to facilitate movement transition, e.g., during transfer or to make use of remaining upper extremity function.
Walking is a complex process, which requires adequate voluntary motor function, sufficient coordination of leg movements, and – often neglected – appropriate sensory feedback, in particular proprioceptive feedback. These basic prerequisites allow to shift the body weight on one side during the standing phase, achieve an upright posture and stability of the trunk, maintain the balance, and adapt to the environment as needed. For successful restoration of walking function, sufficient joint mobility in the lower extremities represents an important prerequisite [30]. In the course of locomotor training, auxiliary equipment including support (compensation) through the intact upper extremities might be necessary. Therefore, this chapter will not only focus on the task-specific aspects of locomotor training but in addition discuss supporting elements, which are key for restoration of locomotor function such as trunk stability, endurance, and the implementation of supportive devices (e.g., orthoses).
23.3.3 Task-Specific Locomotor Training
In order to learn or relearn defined motor skills, the principles of motor learning have to be employed. These principles rely on practice (number of repetitions) and augmented feedback about performance. Moreover, training needs to be task specific – if you want to walk, you have to walk. An optimal rehab program aiming for recovery of walking function should not only rely on task-specific locomotor training. Supporting measures, e.g., trunk stability or muscle training (see below) have to be employed to improve the efficacy of task-specific training. Unfortunately, evidence in respect to the optimal timing/dose of task-specific training, the most efficient feedback approach or the ideal balance between task-specific and unspecific training is scarce.
The most important principles for locomotor training are increasing the ability of the lower extremities to take on weight and reducing the amount of weight taken on by the upper extremities, augmenting sensory input, and strengthening movement sequences as well as reducing compensatory strategies (e.g., assistive equipment, therapist support) [3, 31]. In the early phase after spinal cord injury, in particular in cases of more severe motor impairment, automated locomotor therapy represents an important therapy option. Despite severe sensorimotor deficits, task-specific training can be employed at a rather high repetition rate without exhausting the therapist too much [3, 32]. However, the limited variability and perturbation options due to the restrictive nature of robotic assistance represent the downside of such a therapy [31]. Until now none of the proposed task-specific locomotor training concepts have been clearly shown to be superior in patients with incomplete SCI [33]. The choice of the machines to assist training depends on the extent of sensorimotor deficits in the lower extremities and trunk as well as the cardiopulmonary capacity.
In patients with a high level of injury, severe sensorimotor deficits and orthostatic dysregulation are treated first on a tilt table, which allows stepping movements (see below). Once orthostatic dysregulation has ceased, body-weight-supported treadmill training with exoskeletal support will be tested. In case only minor leg assist is required, stepping movements can be induced without external support, and body weight can be taken over at least partially by the patient; treadmill training with body-weight support, however without exoskeletal support of the lower extremities, will continue. Subsequently treadmill training will be mixed with overground locomotor training and as soon as possible replaced by overground training activities (Fig. 23.1).
Fig. 23.1
Practice of walking function in an incomplete SCI patient. (a) Body-weight-supported treadmill training with exoskeletal support (Lokomat®). (b) Overground walking on parallel bars. (c) Overground walking on parallel bars with visual feedback (mirror). (d) Initiation of overground walking by getting up from the bench to stand. (e) Overground walking with a walker on a homogenous surface
During supported treadmill training, requirements for overground mobility should already be addressed by the therapist. Ideally, at the end of each treadmill session, the progress in locomotor function should be practiced without assistive devices. Depending on the degree of neurological recovery, getting up from height-adjustable benches, weight shift while standing, taking one step forward and to the side, stepping on the spot, or overground walking can be exercised [34].
23.3.3.1 Locomotor Training Devices
Tilt Table with Stepping Device
The tilt table with stepping function (ERIGO®) is based on a traditional tilt table allowing stepping with a physiological load pattern in combination with an adjustable tilt and stepping frequency. The patient is secured through a harness with a chest and shoulder fixation (Fig. 23.2). Each thigh is fastened by a cuff and each foot is fixed on a footplate by two straps. The upper body part of the tilt table can be continuously tilted from the supine position up to an angle of 80°.
Fig. 23.2
Tilt table with stepping function
To realize a physiologically gait-related loading of the foot, a special spring damper was integrated in the footplate: Load is applied to the foot sole during the stance phase (hip and knee extension) due to clamping of a spring beneath the plate. In case of hip and knee flexion, the spring is released from the plate and load reduction is generated. The overall load on the foot increases with the degree of tilting since the patient’s body weight becomes more and more exposed to gravity pushing against the spring-damped footplate [35].
Stepping movement requires loading of the legs to induce a patterned leg muscle activation in healthy subjects and individuals with spinal cord injury. The appearance of a locomotor pattern depends on afferent input detected by “load receptors” in combination with hip joint position-related proprioceptive input [36, 37].
The efficacy of ERIGO® training has only been demonstrated in ameliorating orthostatic dysregulation [38]. Heart rate and blood pressure increased over time superior to effects seen with a tilt table without stepping function. It can be assumed that early training with the ERIGO® improves locomotor function. However, this has yet to be determined. Nevertheless the ERIGO® is employed to practice gait training in patients with poor sensorimotor function at a very early stage of rehabilitation. The concept behind this strategy is to deliver weight bearing to the legs as early as possible in order to avoid maladaptive changes on one hand and to prepare an optimal setting for subsequent more task-specific locomotor training [3].
Manually Assisted Body-Weight-Supported Treadmill Training
Treadmill training with body-weight support has become an important part of gait rehabilitation for patients suffering from incomplete SCI. In addition to an increase in walking speed and walking distance as well as a reduction in the need to use assistive devices, locomotor training has also been correlated with an increase in bone and muscle mass along with positive cardiovascular effects [5, 31, 39–43]. Comparing standard physical therapy alone with a combination of body-weight-supported treadmill training and standard physical therapy in patients with acute incomplete SCI indicated that patients receiving the combinatory treatment gained independence from assistive devices/walking aids more rapidly and achieved a higher walking speed than patients with standard physical therapy [44].
Treadmill training is ideally suited to implement the abovementioned principles of locomotor training. Body-weight support can be adjusted to the maximum weight transfer possible to both legs (it should still be possible to straighten knee and hip joints). As a consequence, the amount of weight taken by the upper extremities [3, 45–47] can be reduced. In addition, walking speed can be adjusted close to the average walking speed (0.75 – 1.25 m/s) [3, 40]. Treadmill training allows almost physiological joint movements of the hip, knee, and ankle joints, with particular emphasis on the hip joints [3, 40, 46] including an upright positioning of the trunk [3, 40]. Depending on injury severity, 1–2 therapists have to support coordinated leg movement during swing and stance. Therapy goals have to be reevaluated for each therapy session and respective variables of the walking device have to be adjusted accordingly. Objectives can be to increase walking speed, to reduce body-weight support, to reduce the amount of manual support, or to prolong the training sessions (Fig. 23.3). In the case of reduced proprioception, external feedback via auditory feedback (e.g., therapist) or visual feedback (mirror, technical systems capable to detect gait kinematics) can help to restore a more physiological gait pattern. Instrumented kinematic real-time feedback therapy in individuals with incomplete SCI has been shown to normalize the gait [49].
Fig. 23.3
Decision-making algorithm for standing and step initiation progression (Adapted with permission of the American Physical Therapy Association. ©2005 American Physical Therapy Association [48]). BWST body-weight-supported treadmill, BWS body-weight support
Robotic-Assisted Body-Weight-Supported Treadmill Training
The main objectives to develop a robotic-assisted body-weight-supported treadmill were to reduce the workload of therapists to position the legs and stabilize the trunk while walking on the treadmill, to generate reproducible gait pattern and as a consequence to intensify gait training with a high number of repetitions. In electromechanical devices for automated-assistive walking training machines, end-effector devices can be distinguished from exoskeleton devices. The Lower Extremity Powered Exoskeleton (LOPES®) [50], the Active Leg Exoskeleton (ALEX®) [51], and the Lokomat® represent exoskeleton-based robotic-assisted body-weight-supported treadmills. Examples for end-effector-based devices are the G-EO-System, the LokoHelp, the Haptic Walker, and the Gait Trainer GT1 [52].
Exoskeleton Based Robotic-Assisted Body-Weight-Supported Treadmill Training
The Lokomat (Fig. 23.4) consists of a robotic gait orthosis, a weight support system, and a treadmill. The gait orthosis primarily consists of a hip and knee orthosis which can be readjusted and adapted to each individual patient. Active actuators are installed in the knee and hip joints for the swing phase. The ankle joint movement is supported by a passive foot lifter. In order to achieve a physiological gait, the powered orthosis is controlled by a computer. Here, the actuators for the hip and knee joint movement follow a physiological specification and provide a reproducible gait pattern. This was determined prior to the administration in patients by testing the Lokomat® on healthy subjects. The devices are equipped with a feedback system for self-control of therapy. Once the patient has been positioned in the Lokomat®, only one therapist is required to perform the therapy, to adjust the parameters (speed, weight support, hip and knee position), and – very important – to give instructions. To ensure the patient’s safety, it is recommended that two therapists safely position the patient in the Lokomat® [3, 32, 53]. The Lokomat® has been shown to increase the gait velocity, endurance, and walking distance [54]. In respect to gait quality, the Lokomat® is comparable to manually assisted treadmill training [55–58]. However, the Lokomat® requires less therapists and produces a more reproducible gait pattern.
Fig. 23.4
(a, b) Robotic-assisted body-weight-supported treadmill training with the Lokomat®
End-Effector Based Gait Training
This concept is based on two mechanically driven footplates, whose trajectories simulate stance and swing phases during gait training. As a consequence, the machine moves the feet (end effector). The more proximal joints (knee, hip) follow this movement (e.g., G-EO-System, LokoHelp, Haptic Walker, Gait Trainer GT1 [52]). In a multicenter study with 155 acute non-ambulating stroke patients (DEGAS study), end-effector-based gait training in combination with physical therapy has been shown to be superior to physical therapy alone [59]. More advanced machines such as the “Haptic Walker” consist of programmable footplates to simulate a variety of overground walking conditions (stairs, other obstacles) and to introduce perturbation (sudden slipping) [60]. An evaluation of 18 studies (11 trials used an exoskeleton device, 7 trials used an end-effector device) on gait training in stroke patients showed a higher rate of independent walking after training with the end-effector device [52].
A direct comparison of the Lokomat® and the Gait Trainer GT1 in motor incomplete acute SCI patients (predominantly AIS-D) revealed similar improvements in all outcome categories (Lower Extremity Motor Score, Walking Index for Spinal Cord Injury II scale, 10-m walk test). In the reported study, both systems seem to be an adequate tool to improve walking functions in incomplete SCI patients [61]. However, in SCI patients with severe motor impairments in the lower extremities, proximal and distal joints need substantial support, which cannot be provided by end-effector devices. Here, only exoskeleton-based devices represent a feasible treatment option.
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