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Chapter 7
The Concept of Function
Overview
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Perhaps one of the most important
developments in health care in the
past decade has been the increased
recognition of the importance of the
patient's perception of health and
functional outcomes
Disablement Model
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Pathology/Pathophysiology (the
presence of disease) which may lead to
Impairments (anatomic and structural
abnormalities) which may in turn lead to
Functional limitations (restrictions in
basic physical and mental actions), which
may then lead to
Disability (difficulty doing activities of daily
life)
External modifiers
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External modifiers are those secondary conditions
that may influence the level of disability but are not
directly related to the disease process itself. Specific
examples include:
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The patient’s level of activity
The patient’s reaction to the illness
The patient’s educational background
The compensatory and coping strategies of the patient
The patient’s pain tolerance and motivation
The patient’s personal and health habits
The patient’s level of social support
The patient’s marital status
The extent to which the patient is involved in litigation
and compensation
Pathology
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The term pathology refers to any
diagnosed disease, injury, disorder, or
abnormal condition that is:
– Characterized by a particular cluster of
signs and symptoms and
– Recognized by either the patient or
clinician as abnormal
Pathology
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The severity of the pathology, and
thus the impact that it has on a
patient’s functional status depends on
a number of factors which include:
– Co-morbidity
– The patient’s general physical health
– The age of the patient
– The patient’s nutritional status
Impairment
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(1)
(2)
An impairment can be defined as any
loss or abnormality of anatomical,
physiological, mental, or
psychological structure or function
that both:
result from underlying changes in the
normal state and
contribute to illness
Impairment
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Impairments can be manifested
objectively, for example by reduced
range of motion, articular deformity,
abnormal gait, and the loss of
strength, power, endurance, or
proprioception
Impairments can also be manifested
subjectively, for example through pain
Impairment
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It is important to note that physical
impairment and physical functioning appear
to be separate constructs that do not
necessarily have a clear linear relationship
The Guide to Physical Therapist Practice
uses preferred practice patterns to group
clusters of musculoskeletal impairments that
occur together
Functional limitations
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Functional limitations are restrictions in
performing expected basic physical and
mental actions. Examples include:
– Difficulty with walking
– An inability to put on shoes
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It is important that clinical measurements
assess the patient’s ability to perform tasks
that the patient feels are important
Functional limitations
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The following steps are recommended to
identify functional goals:
– Determine the patient’s desired outcome of the
intervention
– Develop an understanding of the patient’s selfcare, work, and leisure activities and the
environments in which these activities occur
– Establish goals with the patient that relate to the
desired outcomes
Functional limitations
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Functional goals should contain the
following elements:
– Who (the patient)
– Will do what (activities)
– Under what conditions (the home or work
environment)
– How well (the amount of assistance, or number
of attempts required for successful completion)
– By when (target date)
Disability
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Disability may be defined as difficulty in the
performance of social roles and tasks within
a sociocultural and physical environment
(from hygiene to hobbies, errands, to sleep)
due to a health or physical problem
Disability, which may be temporary or
permanent, is the gap between what a
person can do and what the person needs
or wants to do
Disability
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Disability is not necessarily related to any
health impairment or medical condition;
although a medical condition or impairment
may cause or contribute to disability
For example, associations between
pathology and disability have been found for
several health conditions. These include:
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Diabetes
Cardiovascular diseases
Musculoskeletal diseases
Vision related diseases
Disability
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Impairments and functional limitations
are not related to disability in a linear
fashion
Thus, it is even possible for two
patients who have the same disease
and similar impairments and functional
limitations to have two different levels
of disability
The Measurement of
Functional Outcomes
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Functional outcomes measurement is a
process that describes a systematic
method to gauge the effectiveness
and efficiency of an intervention in
daily clinical practice
– The efficiency of an intervention is a
factor of utilization (number of outpatient
visits, length of inpatient stay) with the
costs of care and outcome
The Measurement of
Functional Outcomes
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The ideal functional measurement tool
is one that recognizes and classifies
impairments, functional limitations and
disability using clinical measurements
that qualify and quantify the
impairments