Introduction to Gait Rehabilitation in Spinal Cord Injury

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Original Editor - Ewa Jaraczewska based on the course by Maha Tayseer Mohammad

Top Contributors - Ewa Jaraczewska, Jess Bell and Kim Jackson  

Introduction

The walking recovery for patients with spinal cord injury is a target of various rehabilitative approaches. Understanding prognostic factors influencing recovery is necessary when choosing the most appropriate therapeutic intervention.This article discusses two approaches in gait rehabilitation and factors that help to predict ambulation recovery for patients with a spinal cord injury.

Plasticity-Based Approach

The plasticity-based approach in gait rehabilitation in spinal cord injury (SCI) arises from activity-dependent neural adaptation and training research. The afferent input influences the activity-dependent plasticity of the spinal cord, which affects the neurobiological control of walking. The examples can be found in the studies by Sherrington, Grillner and Rossignol who looked at the input of hip position and the effect of load on retraining walking after SCI. As the result of these studies, the rehabilitation strategies to regain the ability to ambulate by the patient with a spinal cord injury focused on hip extension, load and other sensory elements to facilitate walking.

In a plasticity-based approach, a specific task, like locomotion, undergoes intensive practice in a specific training environment while an appropriate sensory input is provided. The training environment may include a treadmill with body-weight support (BWS), a lokomat, or an Exoskeleton. The sensory input can be offered in a form of limb loading and unloading, trunk posture, hip extension, or limb kinematics.

Example: Locomotor training using a Lokomat.

• The goal is to generate stepping in response to specific afferent input associated with the task of walking
• The general guidelines focus on maximising loading of the lower limbs through body-weight support systems or overground walking with assistive devices

Compensatory-Based Approach

Compensation is "a rehabilitation strategy for non-remediable deficits of strength (force-generating capacity), voluntary motor control, sensation, and balance."It is based on the principles that patients use their remaining abilities (compensate) to complete the task, or the task or environment is modified to achieve the established goal.

In compensatory-based approach a task of walking is accomplished with the use of orthosis and assistive devices, and the outcome depends on the degree of motor and sensory loss.

Definitions of Walking Recovery in Spinal Cord Injury

General Definitions

Functional ambulation is “the ability to walk, with or without the aid of appropriate assistive devices (such as prostheses, orthoses, canes or walkers), safely and sufficiently to carry out mobility-related activities of daily living.”

Ambulatory capacity is "the highest level of walking function achieved within a standardised environment."

Community ambulation is defined as “independent mobility outside the home, which includes the ability to confidently negotiate uneven terrain, private venues, shopping centres, and other public venues.”

Eight dimensions of community ambulation include the following:

• Ability to manage distances
  • Walk distance from 16 to 677m, depending on the community destination.
• Temporal characteristics
  • Gait velocity, cadence, step length, and step time.
• Speed
  • Crosswalk speed requirements range from .44 to 1.32m/s, vary by country and increase with increasing population size.
• Ambient conditions
  • Lighting, air temperature, weather condition
• Terrain
  • Temporal spatial characteristics of ambulatory participants with SCI are affected by the surfaces they walk on.
  • Average stride length, cadence, and walking speed of a patient with SCI are decreased while walking on artificial grass, soft, and pebble surfaces compared to a hard surface.
• Physical load
  • Poor roads condition, side-walks with cracks, pot-holes
• Attentional demands
  • Gait alteration in response to obstacles within the path of travel
• Postural transitions
  • Ability to maintain dynamic balance
• Density
  • The number of people and objects in the immediate surroundings

Definitions of Ambulation in Spinal Cord Injury Research

There is no consistent definition of walking recovery after spinal cord injury. The following definitions are used in the publications that discuss predictors for functional outcome of walking:

• Walking recovery is defined as "regained ability to walk independently in the community, with or without the use of devices and braces."
• Functional ambulation is defined as:
  • "The capacity to walk reasonable distances both in and out of home unassisted by another person."
  • "Independent mobility outside the home to access goods and services in the community.”

Four categories of functional ambulation in spinal cord injury and gait speed requirements:

1. Requires supervision to walk indoors and is wheelchair-dependent outdoors: a minimal speed requirement of 0.09 ± 0.01 m/s.
2. Can walk indoors but is wheelchair-dependent outdoors: a minimal speed requirement of 0.15 ± 0.08 m/s.
3. Requires a walking aid outdoors (“assisted walker”): a minimal speed requirement of 0.44 ± 0.14 m/s.
4. Walks without aid: a minimal speed requirement of 0.70 ± 0.13 m/s.

• Outdoor walking is defined "as the self-reported ability to walk more than 100 m outside using one cane, leg orthosis only, or no assistive devices."
  • The ability to manage curbs is considered a critical task for independent community ambulation

Predictors for Functional Outcome of Walking

Motor and Sensory Loss

• Moon et al. have found that hip flexors strength followed by knee extensors are the most important contributors to regain an independent walking in patients with incomplete SCI.
• A clinical prediction rule for ambulation outcomes after traumatic spinal cord injury includes motor scores of the quadriceps femoris (L3), gastrocsoleus (S1) muscles, and light touch sensation of dermatomes L3 and S1.
• The score greater than 33 for the motor scores of the quadriceps (L3), big toe extensors (L5), and the light touch sensory score (S1) indicate the likehood of the patient to regain outdoor walking ability one year after spinal cord injury.
• According to Cathomen and colleagues The motor score of the myotomes L2 and L3 allow us to differentiate between walkers and non-walkers. The motor score of myotomes L4-S1 are considered prognostic factors for indoor versus outdoor walkers (with and without aids).

Level of Injury and Severity of the Spinal Cord Lesion

The first examination of the patient with the SCI is performed at 72 hour after the lesion by using The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). It allows us to determine the neurological level of injury and the severity of the lesion. The ASIA Impairment Scale (AIS) A through D defines the complete and incomplete lesions.

Severity of the Spinal Cord Lesion

Patients with the following severity of the spinal cord lesion may or may not recover their walking ability:

• AIS A:
  • Achieving functional walking is very limited.
  • 14% of patients who converted to incomplete injury recovered some walking function.
  • Patients with spinal cord injury at the thoracic or lumbar levels (T12-L3) who regain some walking abilities will need the support of braces and devices to walk.
  • Gait is characterised by slow average velocities and great energy expenditure, which may not be functional for the patient.

• AIS B:
  • About 33% of patients will recover the ability to ambulate.
  • Pinprick preservation is a positive factor in walking recovery as compared with a light touch only (less extensive damage to the spinothalamic tracts and posterior column)

• AIS C:
  • About 75% of patient have a positive prognosis for walking recovery.
  • It affects patients converted to AIS D and patients with AIS C who achieve some walking function
  • Walking recovery affects mostly patients with low thoracic or lumbar lesions
  • Patients will be able to ambulate with braces and devices
  • Age is a strong prognostic factor. 80-90% of patients younger than 50 can walk functionally. 30-40% of older patients can achieve the same.
• AIS D:
  • A very good ambulation prognosis at 1 year post-injury.
  • Most patients regardless of age will likely be able to walk upon the discharge from the rehabilitation facility.

Level of Injury

Patients with the following level of spinal cord injury may or may not recover their walking ability:

• T11-T12 levels
  • May be able to ambulate at home with lower extremity orthoses and a walker.
• L1-L2 levels
  • May be able to ambulate with KAFOs for short distances but they need a wheelchair for a long distance.
• L3-L4 levels
  • May be able to ambulate socially with elbow crutches and ankle foot orthoses.
• L5 and lower
  • May be independent in all activities

Lower Extremities Range of Motion

Spasticity or contracture can prevent meeting the following joint range of motion requirements for walking recovery:

• Full range of knee extension is needed to use a knee-ankle-foot orthosis (KAFO) for ambulation.
• An adequate ankle dorsiflexion allows to achieve foot clearance.
• A minimum zero degrees of hip extension range is necessary to allow the patient to lean backwards and move the centre of gravity of the trunk poste­rior to the hip joint to achieve standing when hip extensor muscles are absent.
• 110 degrees hip flexion allows the patient transition to standing from sitting with locked KAFOs.

Cardiovascular Endurance

"Walking requires increased energy demands on the body and on the cardiovascular system and walking with assistive devices will pose further increased demands."---Maha Tayseer Mohammad

• A swing-through crutch-assisted gait with bilateral knee-ankle-foot orthosis requires 43 per cent more of an average rate of oxygen consumption than that of the patients who use a wheelchair and 38 per cent greater than is used for normal walking.
• A swing-through crutch-assisted gait with bilateral knee-ankle-foot orthosis requires 38 per cent more of an average rate of oxygen consumption than that of the patients who walks with a normal gait pattern.
• Furthermore, the paraplegics in whom the hip flexor and knee extensor muscles were intact bilaterally and who were able to walk with a reciprocal crutch-assisted gait, but did not require knee-ankle-foot orthoses, did no better. They had a rate of oxygen consumption that was 20 per cent greater than that required for wheelchair use and 15 per cent greater than that required for normal walking.their mean walking speed was the slowest of all of the groups. These findings account for the common clinical experience that most paraplegics who require a knee-foot-ankle orthosis bilaterally and use a swing-through crutch-assisted gait prefer to use a wheelchair, and discontinue walking as the primary means of mobilization after gait-training.

Assistive Devices

There are two primary goals of rehabilitation of patients with SCI: (1) to increase their independency, and (2) to improve their health status. A prolonged wheelchair use has its disadvantages which include :

• restriction to mobility due to architectural barriers
• decubitus ulcers
• osteoporosis
• joint deformities, including hip joint adduction contracture

However use of orthosis for ambulation in spinal cord injury come with its own list of problems that include:

• Donning and doffing of the orthosis takes a significant amount of time
• Depending on the style of walking, there is a high percentage of the force applied on the upper limb musculature. Up to 55% of body weight can be applied on the crutch during walking leading to shoulder pain.
• High energy demand during ambulation with orthosis and slow walking speed of individuals with SCI with an orthosis.

Orthosis

Patients with a spinal cord injury who require a knee-foot-ankle orthosis bilaterally for swing-through crutch-assisted ambulation prefer to use a wheelchair. They use wheelchair as the primary means of mobilisation and discontinue walking after gait-training due to :

• high energy demands during ambulation
• slow walking speed

"The performance of SCI patients and the efficiency of treatment approaches should be evaluated with regard to all aspects of functions, such as activities of daily living and participation."

Hip-Knee-Ankle-Foot Orthosis (HKAFO)

HKAFO is an orthosis that allows a reciprocal gait. It is designed with hybrid metal and plastic with droplock knee joints and plastic AFO at neutral.

Patient example: T12, AIS A SCI presented with the following:

• bilateral lower extremity paralysis
• good trunk and arm control
• absent sensation
• mild lower extremities edema
• 1+ increased tone based on Modified Asworth Scale

Knee-Ankle-Foot Orthosis

A walking speed with swing-through crutch-assisted gait with bilateral knee-ankle-foot orthosis was slow in comparison with wheelchair propulsion or normal walking.

Ankle-Foot Orthosis

the paraplegics in whom the hip flexor and knee extensor muscles were intact bilaterally and who were able to walk with a reciprocal crutch-assisted gait, but did not require knee-ankle-foot orthoses, did no better. They had a rate of oxygen consumption that was 20 per cent greater than that required for wheelchair use and 15 per cent greater than that required for normal walking.their mean walking speed was the slowest of all of the groups.

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