Assistive Devices for Ambulation




Interacting with other people and the environment is fundamental to quality of life. Canes, walkers, and crutches increase, maintain, or improve functional capabilities of many individuals with neurologic disorders. Canes offer a choice of handle, shaft, and base. Walkers have various types of base, uprights, handgrips, platforms, and accessories. Crutch designs include underarm, triceps, forearm, and platform. Orthoses, particularly ankle foot orthoses and knee ankle foot orthoses, are often used to stabilize or immobilize lower limb segments while walking. Studies have shown the benefits of traditional assistive devices on gait, when prescribed and used properly.


Key points








  • Assistive devices serve many functions to improve quality of life.



  • Examination should include neuromuscular, cardiopulmonary, and orthopedic factors, as well as an assessment of the home environment and funding sources.



  • Various designs are available.



  • Fitting is critical to optimum function.



  • Appropriate gait can maximize patient performance.






Introduction


For the patient with a central nervous system (CNS) disorder, assistive devices—canes, walkers, crutches, and orthoses—can make the difference between existing largely in the confines of home and engaging in the wider community. Ambulation aids have been used since the Neolithic period.


Selecting the appropriate aid requires considering the amount of stability the patient requires for safe ambulation. For those with CNS disorders, device selection may progress from parallel bars to a large base quad cane and later to a single-point cane needed only when maneuvering outdoors, as neurologic recovery occurs, or in the reverse sequence, in the case of a progressive disorder.


Assistive devices serve one or more of the following functions:




  • Improve balance



  • Assist propulsion



  • Reduce load on one lower limb or both



  • Transmit sensory cues through the hands



  • Obtain the physiologic benefits of upright posture



  • Maneuver in places inaccessible to a wheelchair



  • Notify passersby that the user requires special considerations, such as additional time when crossing streets or a taking a seat on the bus.



Technological advances in materials and designs have multiplied options. Changing demographics and social mores have broadened the market. No longer is it a rarity to see someone in a shopping mall using a walker. Mobility-related assistive technology can be obtained through Medicare’s durable medical equipment benefit and the Department of Veterans Affairs. Nevertheless, a nationwide sample of 3485 older Americans showed that income and insurance affect the use of canes and other assistive devices.


The prescription should specify the aid most likely to maximize the patient’s function; the individual’s goals and personal preferences must be considered also. Ongoing device modification or progression from one aid to another is an additional responsibility of the clinician. Complexity and variability of funding sources add to the challenge of selecting the device that will meet a given patient’s needs. Input from a physical therapist or an occupational therapist is often valuable in ensuring that the appropriate device is prescribed and in ensuring that the patient (and family, if appropriate) is trained adequately.


Key examination elements affecting device prescription are listed in Table 1 . Even when deemed necessary and appropriately prescribed, some patients, when offered an assistive device, refuse, calling it a sign of disability or senility, or stating that they do not want to “give in” to their condition. It is therefore important that the clinician take the time to explain the rationale for using the device and its potential benefits.



Table 1

Key elements of physical examination for assistive device prescription


















Neurologic factors Coordination
Balance
Psychological, emotional, and cognitive state
Cardiopulmonary factors Heart rate
Blood pressure
Aerobic capacity and endurance
Orthopedic factors Flexibility and strength of hands, wrists, elbows, and shoulders
Weight-bearing capacity of the lower limbs
Availability of well-fitting shoes
Home environment Space to ambulate
Condition of walking surface
Presence of stairs that may obstruct egress from the home
Funding Insurance
Personal financial resources




Introduction


For the patient with a central nervous system (CNS) disorder, assistive devices—canes, walkers, crutches, and orthoses—can make the difference between existing largely in the confines of home and engaging in the wider community. Ambulation aids have been used since the Neolithic period.


Selecting the appropriate aid requires considering the amount of stability the patient requires for safe ambulation. For those with CNS disorders, device selection may progress from parallel bars to a large base quad cane and later to a single-point cane needed only when maneuvering outdoors, as neurologic recovery occurs, or in the reverse sequence, in the case of a progressive disorder.


Assistive devices serve one or more of the following functions:




  • Improve balance



  • Assist propulsion



  • Reduce load on one lower limb or both



  • Transmit sensory cues through the hands



  • Obtain the physiologic benefits of upright posture



  • Maneuver in places inaccessible to a wheelchair



  • Notify passersby that the user requires special considerations, such as additional time when crossing streets or a taking a seat on the bus.



Technological advances in materials and designs have multiplied options. Changing demographics and social mores have broadened the market. No longer is it a rarity to see someone in a shopping mall using a walker. Mobility-related assistive technology can be obtained through Medicare’s durable medical equipment benefit and the Department of Veterans Affairs. Nevertheless, a nationwide sample of 3485 older Americans showed that income and insurance affect the use of canes and other assistive devices.


The prescription should specify the aid most likely to maximize the patient’s function; the individual’s goals and personal preferences must be considered also. Ongoing device modification or progression from one aid to another is an additional responsibility of the clinician. Complexity and variability of funding sources add to the challenge of selecting the device that will meet a given patient’s needs. Input from a physical therapist or an occupational therapist is often valuable in ensuring that the appropriate device is prescribed and in ensuring that the patient (and family, if appropriate) is trained adequately.


Key examination elements affecting device prescription are listed in Table 1 . Even when deemed necessary and appropriately prescribed, some patients, when offered an assistive device, refuse, calling it a sign of disability or senility, or stating that they do not want to “give in” to their condition. It is therefore important that the clinician take the time to explain the rationale for using the device and its potential benefits.



Table 1

Key elements of physical examination for assistive device prescription


















Neurologic factors Coordination
Balance
Psychological, emotional, and cognitive state
Cardiopulmonary factors Heart rate
Blood pressure
Aerobic capacity and endurance
Orthopedic factors Flexibility and strength of hands, wrists, elbows, and shoulders
Weight-bearing capacity of the lower limbs
Availability of well-fitting shoes
Home environment Space to ambulate
Condition of walking surface
Presence of stairs that may obstruct egress from the home
Funding Insurance
Personal financial resources




Canes


Canes are the simplest aids for ambulation. They augment balance and provide sensory feedback from the walking surface. They are made from sturdy materials, such as walnut, oak, and other woods; metal, especially aluminum; and plastics, such as acrylics (eg, Lucite), fiberglass, and carbon fiber. Contemporary canes are sold in virtually every color of the rainbow and may display fanciful patterns.


Cane Designs


Unlike the walking stick, which usually is a straight shaft, perhaps topped by an ornamental knob, canes used in rehabilitation have a handle. Handles are often an inverted “U,” which permits hanging the cane over the forearm or the back of a chair when not walking with it. A pistol grip handle and a shovel handle are other options. An ergonomically shaped handle ( www.CanesCanada.com ) is designed to contact more of the hand, thus contributing to the user’s comfort; the handle is made for right and left hand use.


Cane shafts may be straight, offset, folding, or height-adjustable. Straight shafts are the least expensive and most durable. Folding canes are easier to store; an adult-size cane can be folded to approximately 30 cm.


The base of the cane usually is a single rubber tip, broad with deep grooves and kept clean to provide maximum traction. Other bases are standard and wide-based quadruped (quad), which features a distal rectangle supporting 4 tips, intended to increase the support area. Patients with hemiplegia may not find the 4-footed cane more advantageous than a single tip. Novel designs include the side walker/cane ( www.tfihealthcare.com ), which has 4 widely spaced rubber tips to increase stability, especially when used unilaterally by a patient with hemiplegia. Another base has a spring-loaded tip to absorb shock at initial contact. The Able Tripod ( www.abletripodcane.com ) has a flexible triangular tip which maintains floor contact at a wide range of shaft angles; this tip also absorbs shock and permits the cane to remain upright when not in use. A base with a retractable metal spike increases stability when the user walks on ice.


Cane Fitting


Whatever the device, it must fit properly so that the user can walk optimally. When being measured, the patient should wear the type of shoes that will be worn when using it. Elbows should be slightly flexed, about 30°. The tip of the cane is 5 to 10 cm lateral and 15 cm anterior to the shoe. The handle is approximately at the level of the ulnar styloid or greater trochanter. Canes with a broad base, rather than a single tip, should be positioned so that the edge that flares laterally faces away from the shoe. If the flared side is positioned medially, it might hit the ankle as the person enters the swing phase of gait.


Canes that are too long may skid, reducing support. Too short a cane imposes undue stress on the lumbosacral region. Shorter canes, however, enable healthy subjects to perceive ground touch more accurately than longer canes, suggesting that those with visual impairment will walk more safely with a slight decrease in cane length.


Cane Gait


Most patients use a single cane held on the side opposite the affected (or more affected) leg. The user advances the cane and the affected foot and then steps forward with the unaffected foot. The cane augments balance via light support as well as provides sensory feedback from the walking surface. Haptic cues aid postural control in sighted and blind individuals, particularly when the cane is held in a slanted rather than a vertical position.


The cane is usually kept on the floor during the stance phase on the paretic limb. A cane reduces force throughout the hip. Biomechanical modeling of cane use confirmed that it increases stability. Blount’s classic treatise, Don’t Throw Away the Cane, demonstrated how a cane reduces joint stress. Some individuals prefer to hold the cane in the ipsilateral hand, using the device to reduce foot contact force. A few people insist on using the cane in the dominant hand, regardless of the side of impairment.


Some people, especially those with balance difficulties, walk with a pair of canes.


Kinematic studies of patients with hemiparesis confirmed that a cane held on the uninvolved side reduced mediolateral and anteroposterior sway, regardless of whether a standard or a 4-footed cane was used. Subjects had longer stance time on the affected leg and walked faster with a cane than without one. Other research showed that cane use reduced erector spinae and tibialis anterior activity. A cane is indicated for the patient who cannot apply at least 40% of their body weight to the paretic lower limb. Post stroke patients who walked with a cane had poorer balance and less social participation than those who could manage unaided. As compared with those who required a walker, however, cane users were less impaired.


A cane is often the first assistive device used by patients with multiple sclerosis (MS) to increase walking velocity. Other investigators confirm the utility of ambulatory aids, including canes, for patients with MS.


A cane is often used by community-dwelling older adults to prevent falls. A large-scale survey of older adults revealed that those in poorer health or who had more severe disability were more likely to use equipment rather than rely on personal assistance. A randomized controlled trial demonstrated that assistive technology reduced health care costs for older adults.




Walkers


Walkers are frames, usually aluminum, that provide bilateral support, eliminating the need to control a pair of canes or crutches.


Walker Designs


Walkers are available in many combinations:




  • Base: 4 tips, 2 tips and 2 wheels, 4 wheels, 3 wheels



  • Uprights: rigid, folding, reciprocating, stair climbing



  • Proximal portion: hand grips, platform



The simplest model of walker has 4 legs, each ending in a rubber tip to improve traction. The 4-tip walker provides maximum stability, but must be lifted with each step. They are especially appropriate for high-friction surfaces, such as carpet and grass. Walkers with wheels can be pushed forward to provide moderate stability; they are easier to manage on smooth surfaces, such as hardwood flooring. Wheeled walkers, however, are relatively bulky, thus more difficult to stow in a car.


Other bases with 2 front wheels and 2 crutch tips are available. Two-wheeled walkers may have tennis balls or other glides on the rear uprights to smooth ambulation. The folding steel U-Step ( www.ActiveForever.com ) has a padded seat, hand brakes, and an optional laser light, intended to encourage patients with Parkinson disease to step forward. A walker can have a reciprocating mechanism to accommodate stairs, such as the Universal Stair Climbing Walker ( www.tfihealthcare.com ).


Uprights are vertical or angled and may be height-adjustable. Nova 4900 Traveler 3-wheeled walker ( www.HealthyLegs.com ) has 3 uprights each ending in a wheel. It is easier to maneuver in narrow corridors compared with a 4-wheeled walker. Wide-wheeled and four-tip walkers accommodate obese patients.


Handles may be rubberized grips or platforms. Direct-forming plastic can be used to make the handle more comfortable. The 4-legged hemi-walker with an arm platform is used on one side of the body, in place of a cane. The hemi-walker is more stable than the single-tipped cane.


Users can add a basket or fabric bag to their walkers. Some devices have a hinged seat with a compartment to hold small articles.


On-going governmental research is being conducted to develop a feasible robotic walker.


Walker Fitting


A properly fitted walker allows the user’s center of gravity to stay within the walker’s base. Poor fitting could lead to loss of balance. The elbows should be flexed 15°, with the ulnar styloid at each walker’s handle. Slight elbow flexion allows for downward push, allowing the patient to bear some weight through the upper limbs.


If the handles are too low, the user risks keeping the elbows extended, eventually being drawn into excessive trunk forward flexion. Trunk flexion can inhibit hip extension during the stance phase of walking. The anterior position of the patient’s center of gravity interferes with forward weight shifting, making it difficult to achieve adequate propulsion.


Unduly high handles may oblige the patient to flex the elbows too much and lean excessively onto the walker. The patient who compensates by pushing the walker too far from the trunk risks falling if the person’s center of gravity is behind the walker’s base of support.


Walker Gait


The patient advances the walker so that all tips touch the floor simultaneously. Walkers with wheels should be pushed forward slightly. With either design, the user then steps forward with one foot, following with the other foot. Biomechanical analysis with healthy young adults indicated that hand loads vary with the type of walker gait. Hip flexion angle determines weight-bearing force during walker gait. Walker use reduced vastus lateralis and soleus electromyographic activity. Heart rate and oxygen consumption are appreciably higher with a 4-tipped walker compared with a rolling walker.


Among adults with stroke, walkers improved functional mobility. People with Parkinson disease demonstrate slower gait when using a walker compared with unaided gait. Those with Huntington disease performed better with a wheeled walker than with canes or a 4-tip walker.


Elderly adults walked more slowly with a rolling walker than unaided but did not lag in achieving functional gains in rehabilitation.


Although walkers improve patient stability, they do not eliminate the risk of falling. Those who require walkers have greater physical limitations, resulting in increased fall risk. Forward-leaning posture is common and is associated with falls. An analysis of 47,312 older adult fall injuries confirmed that walkers were involved in 7 times as many injuries as canes.

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Apr 17, 2017 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Assistive Devices for Ambulation
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