Thomas R. Hetzel PT, ATP
Ride Designs, Denver, Colorado

Introduction
Many people who use wheelchairs have a preference for the anterior pelvic tilt and upright to slightly forward oriented sitting, as this allows them to function. If these individuals do not receive proper training, education, and seating intervention, this persistent tendency can lead to adaptive shortening of both muscle and non-contractile tissues that limit the potential for postural correction. This workshop addresses biomechanics, evaluation, and treatment of the anterior pelvic tilt in sitting.

The Process of Assessment and Intervention
Although this course focuses primarily on seating intervention, it is very important that clinicians and suppliers conduct a thorough evaluation to determine all factors influencing their clients’ ability to sit safely and function in their wheelchairs. Intervention is directed towards optimal postural alignment for nondestructive resting postures and preparation for and support of mobility and function. Intervention must be mindful of what people need to do in their wheelchairs, how long they must do “it”, and in what environments. People must be supported in a fashion that promotes maximal independence in mobility and function, yet protects them from skin breakdown.

Intervention
In a most simplistic interpretation of a wheelchair seating assessment, virtually any finding will have an implication for intervention in at least one of the four following categories:
Angles: Any limitation of postural flexibility will have an impact on the angular relationships of seating supports.
Shape: Although many people may have the ability to sit at roughly the same angular relationships, everyone has a unique shape. Each individual’s unique shape will determine the contours of the supports chosen.
Orientation: Once angles and shapes are determined, the orientation of the seating relative to gravity, method of mobility, and environments of use must be determined.

Materials: The choice of materials is tied to many factors including skin care, postural control, breathability and maintenance.

Interventions for the sitter with an anterior pelvic tendency versus the posterior pelvic tendency are very different. Location of support surfaces and orientation of supports relative to gravity are nearly opposite. Lack of attention to these differences often results in people with posterior tendencies sliding out of their chairs, and people with anterior tendencies falling forward away from their back supports. A basic understanding of these principles will lead to more effective seating intervention for the long term.

A word about the environment and out-of-wheelchair positioning.
Don’t assign all responsibility for long term postural care and functional sitting postures to the wheelchair. Ensure that work, home, recreational and educational environments are evaluated and modified to reduce the need for anterior trunk orientation. Assess sleeping postures, as well as all other out-of-wheelchair positions and supports. It is not uncommon to discover that these out of wheelchair positions and activities are feeding into the overall scenario of deterioration. It is also possible to restore or maintain a person’s ability to sit by addressing out-of-wheelchair support and activities.

Summary
Pelvic tendencies in standing versus sitting are different. Understanding why is essential for a wheelchair seating practitioner. Assessment of people relative to their predominant pelvic tendency in sitting is a necessary step in determining appropriate seating intervention. Accurate assessment will lead to definition of clear goals and successful interventions. Effective wheelchair seating will help secure long-term optimal postural alignment for nondestructive resting postures and preparation for and support of mobility and function.