Although the use of powered posterior tilt is very common in power wheelchair scripting, anterior tilt is not as widely prescribed. For clinicians, it can be difficult to determine which power seat functions are reasonable and necessary for a user, and it’s important to understand what anterior tilt is and what it can be used to achieve.What is anterior tilt?
Anterior tilt is where the rear of the seat surface is raised, so that front of the seat slopes down and the knees are now lower than the pelvis. Power wheelchairs can often be scripted with different degrees of anterior tilt or amount of slope available, with amounts of 5°, 10°, 20°, and up to 30° anterior tilt available.
Why script anterior tilt?
The primary reason for scripting anterior tilt is to promote the ability to complete functional tasks. When we’re seated in a level or posteriorly tilted position, our upper limb forward reach is significantly affected. It’s easy to try this out yourself when seated by placing an item on a desk around 50cm in front of you. Make sure you are sitting right back in your chair and that your pelvis is level or slightly posteriorly tilted, a common seated position for wheelchair users. Try to reach forward and pick up your item without anteriorly shifting your pelvis to do so. You might manage to reach your item, but it will be difficult. Many wheelchair users have difficulty moving in and out of an anteriorly tilted position without support, so their functional reach and their ability to complete tasks is impacted.
Prescribing anterior tilt can give wheelchair users the option of being supported into a functional position to complete tasks. It can be particularly useful in completing ADL tasks such as accessing sinks for personal care activities and washing up, reaching items in cupboards, accessing the cooktop, and doing laundry. Anterior tilt can work well with seat elevation, as perhaps a user can elevate to be at the height of an item on their kitchen shelf but are still seated too far back to reach for it. Anterior tilt in combination with elevation can allow full access to that kitchen shelf or other areas. Anterior tilt can also be beneficial in workplaces when a person needs to access certain equipment or areas, or in shops and restaurants when ordering or paying at a counter.
As anteriorly tilting a power wheelchair lowers the height of the front of the seat, it can also sometimes be used to allow a user to fit under tables and benches. For some users, even a small change in seating angle can be enough in helping to manage tone, and anterior tilt can beneficial for this reason.
Anterior tilt can also assist a user with standing transfers. As the seating system can help to move a person partway into a standing position, it reduces the muscle strength needed to stand and can possibly enable a person to complete an independent or assisted standing transfer.
Why script anterior tilt? What does the clinical evidence say?
At GTK, as clinicians we believe strongly in using evidence based practice to guide our interventions. As anterior tilt has only been available in power wheelchairs for a somewhat short time, there isn’t a wide body of evidence looking at the use of anterior tilt. In 2019, a pilot investigation into anterior tilt use among power wheelchair users was published. This study found that the use of anterior tilt may assist in improving performance of functional activities, and noted that additional research is needed to examine the long-term influence of anterior tilt1.
One of authors of this pilot study, Rebecca Yarnot (University of Illinois), also completed a thesis in 2019 entitled ‘Perceptions of anterior tilt seat function among power wheelchair users: A qualitative study’. Her research found that users found anterior tilt to be beneficial in a variety of community studies, however found the safety equipment (such as knee and chest supports) restrictive2.
We anticipate that there will be more clinical research conducted over the coming years regarding anterior tilt and eagerly await its findings. Like all power seat functions, anterior tilt is not appropriate for all wheelchair users. Your GTK consultant can work with you during the wheelchair trial process to see what power seat functions would be beneficial for your clients.
- Rice, L.A., Yarnot, R., Mills, S. & Sonsoff, J. (2019). A pilot investigation of anterior tilt use among power wheelchair users. Disability and Rehabilitation: Assistive Technology, 100(10), e36.
- Yarnot, R.K. (2019). Perceptions of anterior tilt seat function among power wheelchair users: a qualitative study (thesis). University of Illinois.