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When it comes to enhancing mobility performance for wheelchair users and others with mobility impairments, it is useful to think in terms of the Personal Mobility Model (PMM)[1].
The PMM is made up of three components of:
1. Device – The assistive device that is currently improving the person’s mobility.
2. Environment – The immediate physical surroundings that the person must navigate.
3. Person – The range of mobility ability of the individual relative to his/her disability.
Each component of the PMM interacts with the components creating three intersections of:
A. Person/Device – The relationship between the Person and the Device.
B. Device/Environment – The relationship between the Device and the Environment.
C. Environment/Person – The relationship between the Environment and the Person.
Therefore, a person’s resulting mobility performance[2] consists of six interconnected aspects that all work together. The PMM enables the deconstruction of a person’s mobility into individual aspects in order to determine how to increase overall performance in the most effective manner.
Typically, most people only look at one or two aspects of the PMM. They rarely consider all the aspects in totality. Most likely this happens because they are unaware of the importance or existence of the other aspects due to personal bias or lack of knowledge.
For example, let’s examine the hypothetical case of John, who is a manual wheelchair user. When John is getting around in his neighborhood, his PMM can be describes as follows:
1. Device = Manual wheelchair.
2. Environment = The layout and construction of his neighborhood such as sidewalks, curb cuts, roads, steps, stairs, doors, people in his vicinity, current weather, and other physical features and influences.
3. Person = John’s particular physical and mental abilities and limitations.
A. Device/Environment = How well does a manual wheelchair function in this neighborhood in general, separate of John’s specific abilities? What areas are possible/not possible to navigate? B. Environment/Person = How well does John navigate and move around in his neighborhood separate from the fact he is using a wheelchair? In other words, does John know his way around? Does he take the flattest and smoothest route or does he make it harder on himself by going up hills and over rough terrain? C. Person/Device = How well does John’s manual wheelchair fit him? Is it optimized for him?Is he able to maximize the performance of his wheelchair through acquired skill and conditioning?
One of the main purposes of the PMM is to illustrate that a person’s mobility is affected by all of these six aspects. Depending upon the specific circumstances, the greatest gain to the person’s mobility (most bang for the buck) may not be from the area being considered.
Typically, disability rights advocates focus primarily on changing the Environment to make it more universally accessible. Wheelchair designers and manufacturers attempt to create mobility devices that can navigate more varied terrain. Physical Therapists attempt to improve the person’s physical abilities. Occupational Therapists try to educate and improve upon a variety of areas depending on their own level of expertise.
These entities usually focus on a particular aspect(s) of the PMM. There is no centralized and reliable source for exchanging information and knowledge on all of the aspects.
Education and training for wheelchair users is inconsistent at best. Completely nonfunctional at worst. The six aspects that make up the PMM are many times treated individually, not as a synergistic whole.
It is my hope that a greater understanding the Personal Mobility Model will provide a step towards educating wheelchair users, the medical industry, and designer and manufacturers of mobility products on the many different ways to improve personal mobility for people with disabilities.
[1] The PEO Model from Occupational Therapy is a tool that uses a similar methodology for analysis of Occupational Performance as opposed to Mobility Performance.
[2] This video provides some examples of personal mobility for wheelchair users.