Wheelchair Design

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Introduction

The aim of wheelchair design is to produce wheelchairs that perform well and can provide appropriate seating and postural support without compromising strength, durability and safety. This can be achieved when government authorities, manufacturers, engineers, designers, service providers and users fulfil their respective roles with respect to design.

Wheelchair designs vary greatly to take account of the diverse needs of users. To ensure wheelchairs are appropriate, designers and providers must thoroughly understand the needs of the intended users and their environments. Users’ needs are best met when there is a variety of models from which to choose. Wheelchairs should be designed to enable their users to participate in as many activities as possible. As a minimum, a wheelchair should enable the user to lead a more active life without having a negative effect on their health or safety. Comfort and safety are two important factors affecting the quality of life of long-term users.

According to WHO the design of a wheelchair depends on a number of factors:

• The physical needs of users
• The environment in which the wheelchair will be used; and
• The materials and technology available where the wheelchair is made and used.

Considerations

Functional Performance

Functional performance is how a wheelchair performs for different users in different environments. The functional performance of a wheelchair is determined by its unique design and features. There are many compromises to consider when designing or selecting for different uses. This section provides information on the key features of a wheelchair that affects the main categories of performance and how to evaluate them. It also outlines compromises that need to be considered when choosing different design features. To meet the functional performance needs of individual users, a range of wheelchair designs and sizes are needed.

Wheelchair Stability

Manoeuvrability

Pushing Efficiency

Other Functional Performance Characteristics

Seating and Postural Support

How a user’s body is supported by the wheelchair. This includes comfort and pressure relief. All wheelchairs provide seating and postural support as well as mobility. Good postural support is important for everyone, especially for people who have an unstable spine or are likely to develop secondary deformities. The significance of good seating and postural support can mean the difference between the user being active and an independent member of society and the user being completely dependent and at risk of serious injury or even death.

All body contact surfaces provide seating and postural support. Together, these parts of the wheelchair help the user to maintain a comfortable and functional posture and to provide pressure relief. This is very important for users who have problems with skin sensation. The common areas where likely problems might occur are shown in Fig. 2.5 and 2.6.

The recommendations set out in Box 2.4 can be used as a guide in the design and selection of basic 2wheelchairs. They do not cover wheelchairs that provide a higher level of adjustability or custom adaptations for users who require more complex postural support.

Strength, Durability and Safety:

The goal of this section is to help define what makes a safe and reliable wheelchair, and how to evaluate and report these attributes to stakeholders (see Box 2.8). When a wheelchair fails, the user is not only at risk of injury but may not be able to go anywhere or do anything until the wheelchair is repaired or replaced. Apart from ensuring that the wheelchair is safe and effective, evaluating strength and durability is a way of gathering important information that can be useful for all stakeholders – users, designers, providers, manufacturers and funding agencies. Keeping accurate records of the results of strength and durability tests will help wheelchair designs evolve so that their quality and effectiveness continually improve.

A wheelchair should be strong and durable enough to withstand the wear and tear placed on it by the user and to keep the user safe. Wear and tear consists of:

• static forces

• impacts

• fatigue stresses from use over time.

Needs of the User

an appropriate wheelchair should make it easier for wheelchair users to carry out the things they need to do. Wheelchair users need to be able to get in and out of their wheelchair, to push their wheelchair, to fold the wheelchair for transport and storage and carry out their daily activities. The right type of wheelchair can make it easier for the wheelchair user to do all these things.

Environment

Ergonomics

Posture Support

Production and Supply

Wheelchairs may be produced nationally or imported. To provide a range of wheelchairs, some countries may choose to support both national production and importation. Each supply method has an appropriate application.

With many different needs within a region, a variety of supply methods may be suitable, the long term goal being sustainable solution. It is recommended that all wheelchairs, irrespective of supply method, meet or exceed national wheelchair standards and be repairable locally.

When determining whether to acquire wheelchairs via import or local production, decision-makers are advised to balance a variety of factors including:

• the needs of local wheelchair users;
• the quality and variety of wheelchair models;
• the long-term reliability of supply of wheelchairs and spare parts;
• the possibility of influencing the design, features, materials, etc.;
• the purchase price;
• the cost of repair and replacement;
• the effect on local employment and wheelchair production;
• coordination of supply with an overall plan for wheelchair provision;
• the amount and term of the funding available; and
• policies and strategies, including long-term sustainability.

References