Tuesday, October 13, 2015

Pros and Cons Seating Systems as Extrinsic Enablers for Assistive Technologies


Needs Served By Seating Evaluation for Seating

Clients with disabilities most commonly identified with seating, positioning and mobility problems include those with: spinal cord injury, traumatic brain injury, cerebral vascular accidents, cerebral palsy, multiple traumas, spina bifida, amputations, cardiac diseases, metabolic disorders, diabetes and low back pain.

Biomechanical Principles

The seven principles are: 1. Stability, 2. Maximum Force, 3. Maximum Velocity, 4.Applied Impulse,

5. Direction, 6. Angular Motion, 7.Angular Momentum

 Principle #1- Stability

 There are two types of stability:

 1.) Linear

 a.) Static- at rest a person’s linear stability is proptionial to the mass and the frictional forces orruttin between the person and any supporting surfaces.

b.) Dynamic- While moving a person's linear stability is directly related to momentum.  The heavier the athlete and the faster his movements, the greater the person's linear stability.

 2.) Rotary

 a.) Resistance against being pushed over

b.) Resistance of rotating an object or person against a reduction in rate of spin.

The lower the Centre of gravity the lager the base of support, the closer the line of gravity to the Centre of the base of support, and the greater the mass the more stability.

 Principle #2- Maximum Force

 In order for maximum force to be produced it requires the use of as many joints in the body possible.

 Principle #3- Maximum Velocity

For maximum velocity to be produced it requires the use of the joints from largest to smallest.  Leaving out one joint can reduce the overall force.

 Principle #4- Applied Impulse

 The greater the applied impulse, the greater the increase in velocity.

Impulse= Force x Time

Principle #5- Direction

Movement usually occurs in the direction opposite to the applied force.

Principle #6- Angular Motion

 Angular motion is produced by the application of a force acting at a distance from an axis, by means of torque.  Angular momentum increases the closer the force is to the axis.

Principle #7- Angular Momentum

This principle refers to constant momentum when and athlete or object is free in the air.

Principles of Seating for Postural Control

The knowledge and application of biomechanical principles form the basis for the provision of optimal seating and positioning systems. Biomechanical principles explain body movements. The study of normal healthy body movements is necessary in order to understand how disability and disease cause postural deviations in clients. Optimal seating and positioning systems maintain and improve comfort, health and function. The failure to utilize biomechanical principles is invariably reflected in poorly fitting seating and positioning systems. This failure is realized by reports of discomfort from clients, bodily harm and decreased function. The clients, young or old, may be physically harmed, uncomfortable and unable to function optimally. The understanding and application of biomechanical principles will increase the quality of seating and positioning systems and the overall comfort, function and health of clients. The success of a durable medical equipment (DME) company is dependent upon the knowledge of its employees and the quality of its services.

 Principles of Seating for Tissue Integrity

Proper seating and positioning is critical for people using mobility devices. Sitting all day is hard work—something you surely know if you’re a wheelchair user. If you’re an able-bodied caregiver, however, you may not have given it much thought—until an endless car trip leaves you feeling stiff, aching and exhausted. Skin that bears weight in a wheelchair lives in hostile territory. Pressure, shear, moisture and heat combine to create ideal conditions for the development of decubitus ulcers. In fact, a landmark study found that at least 20 percent of wheelchair users have a skin breakdown in any one year, which means that virtually every user is likely to encounter a skin problem within four to five years. Ottobock specializes in seating and positioning products for users at high risk for skin-integrity issues. You are considered at high risk of skin-integrity issues if any of three statements is true as relates to sitting in your chair.

  • You have a history of redness and/or the presence of open wounds on your seated surface.

  • You cannot do an effective, independent weight shift on a consistent basis.

  • You have impaired sensation and don't check your skin daily and don't practice consistent weight shifts.

The good news is that most pressure ulcers—localized injuries to the skin and/or underlying tissue, usually over a bony prominence—are preventable. For that reason, anyone who spends their days in a wheelchair needs three types of skin protection as it relates to their wheelchair seating system.

 Principles of Seating for Comfort Technologies for Seating and Positioning Management

Seating for most industrial applications generally includes an adjustable backrest, a suspension system, a fore-and-aft track adjustment, an up-and-down seat adjustment, and sometimes an armrest and/or footrest. Some manufacturers also include devices for lumbar region support. Unfortunately, many factors combine to make it difficult to design a suitable seat for underground mobile applications. These include height limitations due to seam thickness, fore-aft and lateral space limitations due to the small size of the operator’s compartments, and the natural wear and tear in the harsh underground mining environment. To compound the problem, suspension systems used extensively in surface mining equipment and other off-road applications cannot be used with underground mobile underground mining equipment, except in the higher-seam mines due to the strict restriction on height.

Properties of Materials Used To Construct Seating Systems

There is a multitude of seating, positioning, and mobility devices available.  Each technology device offers specific and unique characteristics that may or may not meet the needs and be consistent with the skills of the client.  As a result, technologies must be systematically evaluated to determine specific features and custom configurations that most appropriate match the client’s individual needs and abilities. 

·         Power Wheelchairs:  front wheel drive, mid-wheel drive, rear-wheel drive.

 ·         Specialty controls:  hand, chin, breath, head, body switches.

      ·         Special Functions:  seat lowering to floor level, seat elevation, standing, tilt, recline, hybrid tilt-recline.

 ·         Power Operated Vehicles (POV): 3-wheeled scooters, 4-wheeled scooters

      ·         Manual Wheelchairs:  folding frames, rigid frames, assisted propulsion.

     ·         Skin and Pressure Evaluation:  pressure mapping.
    
·         Pressure Relieving Systems:  cushions, tilt, recline, hybrid tilt-recline, standing options (i.e., as part of wc, separate from wc).
        
·         Ambulatory Devices:  walkers, crutches, canes.

     ·         Orthotics:  knee-ankle-foot orthotics (KAFOs), ankle-foot orthotics (AFOs), super malleolar orthotics (SMOs), orthotics (shoe inserts), myo-orthotics (electrical stimulation).

       ·         Prosthetics:  above-knee (A/K), below-knee (B/K), ankle-foot.

 

 

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