Assistive Mobile Devices
Assistive mobile devices are tools designed to improve the mobility and stability of persons who have difficulty moving independently.
Assistive mobile devices include canes, crutches, walkers, and wheelchairs. The devices are used to allow a person to continue to be mobile; otherwise the person may have difficulty moving about independently. A large variety of medical conditions may lead to the need for a mobility aid. A partial list includes:
- cerebral palsy
- multiple sclerosis
- brain or spinal cord injury
- Parkinson's disease
- muscular dystrophies (progressive muscle-weakening disorders)
- ataxias (group of disorders affecting balance and coordination)
- amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, a progressive disease causing muscle weakness
- trauma of the lower extremities, such as sprain or fracture
- leg or hip pain
The choice of mobility aid will depend less on the patient's disease or disorder and more on the current level of mobility. Factors that affect mobility include leg strength, balance, endurance, fatigue, pain, generalized weakness, altered limb sensations, and limb coordination.
A cane is appropriate for a person with good strength and endurance, whose balance is impaired either due to slowed movements, loss of isolated muscle control, or ataxia, or who has pain upon full weight bearing on one side. A cane is often used when the impairment is on one side, as from an ankle sprain or localized polio. The cane provides a third point of contact with the ground (along with the two legs), making a tripod that is far more stable than the two legs alone. The cane can support the weight, although prolonged weight bearing is uncomfortable on the wrists. Two canes may be used for extra stability. A cane typically has a rubber tip for traction, and may have a four-pronged base ("quad-cane") for even more stability. The cane and the favored leg move in unison to allow the cane to absorb the weight of the step.
Crutches are used in pairs. The patient uses the crutches by gripping them and clasping them between the arm and the side of the chest, or the arms may slip through short tubular "cuffs" to reach the handgrips. The latter style is more commonly used for long-term disabilities such as cerebral palsy, while the former is often used for temporary fractures or sprains. In the case of a fracture or sprain, the goal is to keep weight off the injured limb during healing. Crutches allow the patient to use only a single foot, plus the two crutch tips, for the stable tripod stance. The patient's wrists support the weight, not the armpits. Cuffed crutches may be used when there is limited coordination in the legs, or when (as with polio) the
legs are too weak to support the body's weight in full. The cuff transfers some of the bearing weight to the forearm, relieving the strain on the wrists.
Walkers provide the maximum support and stability for a person who walks upright. The walker has four legs, or two legs plus two wheels, or four wheels. The walker's wide base of support provides great stability, important for those patients with balance problems. The frame supports the weight while the patient takes small steps forward. Following that, the patient lifts the walker and moves it forward, or rolls it forward (if it has wheels), and plants it again while taking another set of steps. Walkers move in front of the patient, but can still be useful for a person prone to fall backward. In this case, the height of the walker is lowered to ensure that weight is always tilted forward onto the walker. Wheeled walkers often have hand-operated brakes for greater safety, and may be equipped with a seat to allow the patient to sit down for short periods while ambulating.
Wheelchairs are designed for people who cannot support their weight on their legs, or for those whose balance is too impaired to stand. Wheelchairs may be short-term or long-term mobility aids, and may be used intermittently or all the time, depending on the requirements of the patient. There are several major designs for wheelchairs, including folding versus rigid, and manual versus powered. The technological developments in wheelchair design have made them extremely versatile and dependable, but at the same time have increased the cost of the more expensive models into the thousands of dollars. All wheelchairs have adjustable footrests to allow the legs to be held in a variety of positions.
The folding manual wheelchair is perhaps the most widely used style. Older folding chairs, still seen in airport
More modern folding chairs provide a firm platform for a custom seat, allowing a choice of seating cushion. This is highly important for anyone who will spend long periods in the chair. Lack of proper seating leads to pressure sores, chafing, and skin breakdown. Choice of the right seat is one of the most important decisions in fitting the wheelchair. Seat styles include foam, air cushion, and other materials.
Rigid manual chairs are lighter than folding models, at the expense of some portability. Rigid chairs are also used by wheelchair athletes who compete in marathons and other events, attaining speeds of 30 miles per hour or more. These chairs are custom made for individual athletes, and have little in common with standard manual chairs. All manual chairs do share the same source of power—pushing either by the occupant or by an attendant. Frequent lubrication and maintenance maintains the chair in good shape to make this task as easy as possible.
Power wheelchairs use on-board batteries to drive the wheels, allowing independent mobility to those without enough upper body strength for a long trip in a manual chair. Power chairs are generally controlled by a joystick, although for quadriplegics or others who have lost sufficient arm control, a "sip-and-puff" mechanism is available, in which the patient's inhalations or exhalations into a straw control the direction and speed of the chair.
Coope, Rory. Wheelchair Selection and Configuration. New York: Demos Medical Publishing, 1998.
Short, Ed. Basic Manual Wheelchair Adjustments: A Handbook. Fishersville, VA: Woodrow Wilson Rehabilitation Center Foundation, 2000.
Muscular Dystrophy Association. (April 18, 2004.) <http://www.mdausa.org>.