1.12 APPLICATION OF ERGONOMICS IN REHABILITATION
1.12.2 J OB -R ELATED E VALUATION
1.12.3.3 Product-Related
relevant, the data must be collected in the occupational milieu and simultaneously.
Therefore, the force exerting capacity through the ROM and sustainable velocity and repetition will be essential. Thus, such multidimensional data must be collected in physical, psychological, and social domains (Kumar, 1992). The decision regarding a course of action (treatment, training, return to work, etc.) will depend on the job demand. A quantitative overlap of the patient’s physical and psychosocial capability over the job requirement (Figure 1.23) will allow an ergonomically trained reha-bilitation professional to determine the defi ciencies and select a strategy to manage the case. This hypothetical task requires a great deal of speed, precision, dexterity, perception, cognition, and fast reaction time. On these criteria in this hypotheti-cal example, the identifi ed defi ciencies prohibit to return the worker to work. For this job, the patient needs further rehabilitation. However, there may be another job, which this patient may be able to do. Thus, depending on the severity of defi cien-cies, the patients may be placed either on an alternate job, returned to rehabilitation, or sent for work hardening. Thus, in order to employ rehabilitation ergonomics, one may have to consider a variety of steps and strategies as presented by Kumar (1992) (Figures 1.21 and 1.22).
Although the components of the rehabilitation ergonomics are multiple, they either impact on the “therapist–patient” interface or the “patient–environment”
interface. It will be only through a thoughtful and careful application and execution that we may be able to more or less overcome the barriers to a signifi cant segment of our population, and make a positive contribution to the national as well as world economy. Therefore, the following model represents the theoretical framework of rehabilitation ergonomics (Figure 1.3).
TABLE 1.5
Nature and Severity of Disability by Age Group in Alberta
Disability 15–64 Years 65 Years and Older
Nature
Total 155,725 73,160
Mobility 92,250 56,495
Agility 80,980 49,775
Seeing 18,185 15,560
Hearing 36,655 30,210
Speaking 9,905 3,835
Other 37,575 17,665
Unspecifi ed 15,490 2,145
Severity
Mild 82,220 26,170
Moderate 52,365 27,085
Severe 21,140 19,910
Despite the inherent diffi culties with the market, there are many groups of people associated with the disabled who will be secondary benefi ciaries of such availability and prove to be vocal and powerful advocates. These people will include physiatrists, orthopedists, neurologists, cardiologists, ophthalmologists, and ENT specialists among medical professionals. Almost the entire allied health profession-als including nurses, therapists, and rehabilitation engineers will profession-also constitute a strong supporting group. Lastly, the family and friends of disabled people will also be indirect benefi ciaries of such products in a big way. Of course, the manufacturers and suppliers will also have a vested interest in success of such an endeavor. Since such developments are likely to touch lives of so many, their consideration in depth is a technical as well as moral responsibility of ergonomists.
In a Health and Activity Limitation survey, the Alberta Bureau of Statistics (1989) and Statistics Canada (1990) have divided the disability types into a total of seven categories: mobility, agility, seeing, hearing, speaking, other, and nature not specifi ed. The fi rst two constituted the bulk of disabilities for Alberta (Table 1.5).
The United Nations (1990), in its international survey of disability, identifi ed fi ve broad issues: (a) presence of impairment, (b) presence of disabilities, (c) causes of impairment, (d) social, economic, and environment characteristics, and (e) dis-tribution and use of services and support. For the current discussion, presence of impairments and disabilities are most relevant and are presented in Tables 1.6 and 1.7. A concurrence in classifi cation, description, and defi nition of impairment and disability between different countries still appears to be a fair distance away. A lack of commonality in classifi cation and description of impairment and disability may be a formidable impediment in universalization of solutions. It may, therefore, be the necessary fi rst step to develop a functional categorization regardless of cause and nature of impairment. The discipline of ergonomics is equipped to commence
TABLE 1.6
United Nation’s Classifi cation of Impairments
Category Type Description
Physical (sensory) Aural Auditory sensitivity
Language Language functions and speech
Ocular Visual acuity
Visceral Internal organs and impairments of other special functions, e.g., sexual, mastication, and swallowing
Physical (other) Skeletal Head and trunk region, mechanical
and motor impairments of limbs and defi ciencies of limbs Disfi guring Disfi gurement of head and trunk,
regions of limbs
Intellectual and psychological Intellectual and psychological Intelligence, memory, thinking consciousness, wakefulness, perception and attention, emotive and volitional functions, and behavior patterns
Generalized sensory and others
TABLE 1.7
United Nations (1990) Classifi cation of Disabilities
Category Type Description
Physical (functioning) Locomotor Ambulation and confi ning disabilities Communication Speaking, listening
Personal Care Personal hygiene, dressing, feeding, and excretion Body disposition Domestic disabilities, e.g., preparing and
serving food and care of dependents, disabilities of body movement, e.g., fi ngering, gripping, and holding
Dexterity Skill in body movements, including manipulative skills and ability to regulate control mechanisms Social functioning Behavior Awareness and disabilities in reactions
Situational Dependence and endurance and environmental disabilities relating to tolerance of environmental factor
Other Disabilities of particular skills and other activity
restrictions
the development of a generic functional classifi cation applicable across conditions, which results in similar functional defi ciencies. These criteria can then be incor-porated in design and development of products for use by disabled consumers.
Existing products considered suitable for use by disabled consumers can be tested against the criteria thus generated. Therefore, the scope of ergonomics can readily expand to include rehabilitation, which in fact is a legitimate but relatively unex-plored dimension. Thus, rehabilitation ergonomics may be considered to consist of components as shown in Figures 1.21 and 1.22. An extensive need for a category of product universally needed by disabled people is appropriate clothing. Some cre-ativity and innovation in this area can go a long way to make life so much easier for all concerned. An effi cient functioning of disabled population is not only a moral nicety, but an economic necessity in newly emerging reality of life.
1.12.3.3.1 A Case Study of Ergonomic Product Design
Rheumatoid arthritis (RA) is a chronic progressive disease that affects men, women, and children of all ages. Even with excellent attention to medicine and rehabilita-tion, the disease can be disabling to various degrees. A random survey of 15,268 people found an overall prevalence of RA to be 2.7% , with a maximum prevalence of 5.5% among older females and a minimum prevalence of 0.4% among younger males (Issacson et al., 1987). During periods of disease exacerbation, damage can be done to the periarticular soft tissues. Damage to these structures leads to joint deformities. It is therefore important that the joints and their surrounding soft tissues be protected from stress and inherent weakness. Muscle strength and joint ROM must be maintained, however.
MacBain et al. (1981) suggested that, among other things, the following princi-ples are particularly important in the management of rheumatoid hands. First, discre-tion must be used in exercise and it must be modifi ed appropriately. Second, strong fi nger fl exion should be avoided if there is active synovitis or if laxity is present.
A fi nger load may be magnifi ed from 2.8 to 4.3 times in the effector fl exor tendon (Ohtsuki, 1981). Therefore, if violated, movement may aggravate both tenosynovitis and synovitis. Such forces may cause tendons to gradually stretch with repetitive activity (Goldstein, 1981), further increasing the laxity. An exertion of contractile force would also signifi cantly increase the intra-articular pressure of the infl amed joints stretching the joint capsules (Kumar et al., 1976). Such activities may, there-fore, increase deformity and dysfunction. Therethere-fore, an assistive device can be used to decrease the amount of stress on the soft and infl amed tissues.
A repetitive task such as wringing or squeezing water out of dishcloths or wash-cloths is a task that places deforming forces on the rheumatoid hand (strong fi nger fl exion and ulnar deviation of the MCP joints of one hand and radial deviation of the other (Tichauer, 1978), and should be avoided if joint laxity or active synovitis is present. Using an assistive device to avoid the deforming forces and to place the stress on larger muscles and joints would decrease the stress on smaller, less stable joints and protect them.
Older women are the primary target of RA. More often, they are found to be homemakers and do the wringing or squeezing task many times daily. People with RA have decreased grip strength compared to normal individuals, and have infl ammation and instability, so this task encourages deformities to occur. It is
likely that an assistive device specifi cally designed to perform the task of removing water from cloths would be benefi cial. The purpose of this study was to determine if there was a need for an aid to assist in the removal of water from cloths, and if so, to develop such an aid.
1.12.3.3.2 The Device
Hard plastic was used for the device. Two 10 × 15 cm rectangles were cut and joined together on one of the short ends by copper rivets, forming a wedge-shaped recep-tacle. The angled rectangle was riddled with holes to allow the water to escape. The straight rectangle had a plastic hook riveted to it at a right angle. This hook allowed the device to hand on the spray nozzle on a kitchen sink. A 10 cm long mechanical lever at the end of a 5 cm diameter cam was attached to the front of the device by steel rods. By applying the palm of the hand to the superior aspect of the lever and pulling down, water was squeezed from a cloth placed in the receptacle. The depth of the device (Figure 1.25) that could sit in the sink was 10 cm. The full depth including the hook was 18 cm. A ball of 7.5 cm diameter was attached to the end of the handle to prevent stress concentration at the point of contact with hand.
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FIGURE 1.25 Domestic dish cloth squeezing device.
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2 Energy Cost
Considerations in
Common Disabilities:
Scientifi c Basis and Clinical Perspectives
Suh-Jen Lin
CONTENTS
2.1 Defi nitions of Energy Expenditure and Related Terms ... 42 2.2 Energy Expenditure in People with Orthopedic Disorders ... 47 2.2.1 Amputation ... 48 2.2.2 Joint Immobilization ... 49 2.3 Energy Expenditure in People with Neurological Disorders ... 50 2.3.1 Stroke Patients ... 51 2.3.2 Spinal Injury Patients ... 51 2.3.3 Cerebral Palsy (CP) ... 55 2.3.4 Multiple Sclerosis (MS) ... 57 2.3.5 Parkinson’s Disease and Postpoliomyelitis ... 58 2.4 Energy Expenditure in People with Cardiorespiratory Disabilities ... 58 2.5 Other Considerations ... 59 2.5.1 Assistive Devices ... 59 2.5.2 Wheelchair Propulsion ... 60 2.5.3 Aging with a Disability ... 60 2.5.4 Physical Disability and Obesity ... 61 2.6 Conclusion ... 62 Acknowledgments ... 62 References ... 62
Independent activities of daily living and walking are important basic functions that most people value in life. Walking is one of the fi ve major activities– walking, breathing, hearing, seeing, and speaking. If any of these functions is severely
impaired, the person is considered on disabilities in federal legislation. According to the Americans with Disabilities Act of 1990, signifi cant impairment in at least one of the fi ve major life activities would constitute a disability.
Appropriate energy supply is one of the prerequisites for a person to walk effi -ciently and independently. Maximum energy effi ciency is especially a fundamental phenomenon for all movements and functions. Each daily activity requires a certain amount of energy supply, which comes from the combustion of foods, predominantly carbohydrates and fat, in the body. With appropriate amounts of oxygen delivery through adequate cardiac output, gas exchange in the lung and the working mus-cles, food combustion produces the amount of energy-carrier molecules, adenosine triphosphates (ATP), required for muscular work. Therefore, any functional activ-ity requires a delicate coordination among cardiorespiratory function, neuromus-cular control, and musneuromus-cular activity. People with disabilities often experience high metabolic demand of physical activities compared to their healthy peers, due to impairments in the cardiorespiratory system, neural control, or musculoskeletal per-formance. Before a discussion on the energy expenditure in patients with disabilities, some basic terminology in exercise physiology will be reviewed.
2.1 DEFINITIONS OF ENERGY EXPENDITURE