Hinnovic » Design of a new folding shower-commode wheelchair

Design of a new folding shower-commode wheelchair

Designing a folding shower-commode wheelchairThere are over 220,000 individuals with spinal cord injury (SCI) in the United States today. The majority of them need to use a commode-shower wheelchair for toileting/showering. A survey of veterans with SCI was conducted to seek feedback on existing shower-commode chairs with findings that revealed numerous safety-related issues with these wheelchairs.



From there, a design program was launched following approval of merit review grant application and led to a new and patented shower commode wheelchair.


An iterative design process involving patients and caregivers

Wheelchair prototypeThe team first evaluated existing wheelchairs with patients and caregivers before beginning the design process. From this evaluation, functional and performance criteria were established in order to develop new wheelchair prototypes for clinical evaluation at two VA Medical Centers. Typical of many such projects, an iterative process of prototype development and clinical evaluation was used to develop the new wheelchairs. Responses received from patients and caregivers were incorporated into the next prototype until the new wheelchair design was completed.



  • Safety: wheelchair must not contribute to the development of pressure ulcers, nor cause injuries to patients due to falls while transferring or bending forward to wash the feet.


  • Wheelchair positioning over a toilet: must fit properly over a toilet bowl.


  • Seat design: must be designed to facilitate under seat hand access from 3 sides, be waterproof, provide full thigh support and be cushioned to avoid skin pressure.


  • Seating position: must be sloped 4 to 5 degrees toward the back to hold the user safely in place.


  • Armrests: must swing out of the way for transfers, provide a resting-place for the forearms, support the user’s body weight while hooking under them, or lift themselves or re-position their body.


  • Caregiver friendly: must provide for unrestricted hand access to the perianal area of the patient.


  • Propulsion pushrim/handrims: must be appropriately sized for optimum hand positioning and grip and be coated with non-slippery material to assist use in wet environments.


  • Static stability: must be designed for a minimum tip angle of 20° in forward, rearward, and sideways tipping.



Box 1. Safety and performance criteria



Prototype development and testing

The development process involved the design of adjustable wheelchair frames, in order to establish the proper relationship between seat, toilet bowl and bathroom wall. From there folding wheelchair frames were developed. The frames were tested for static stability in accordance with applicable ANSI/RESNA/ISO standards. With the frame geometry established, the other aspects of the wheelchair development followed (see Box 2).



Seat design:

"C" shape seat designSeveral rectangular seats of various dimensions and hole opening were developed and evaluated with a pressure-mapping system. From these various designs, a new "C" shape seat was created, allowing hand access in three positions (front, left and right side). This seat incorporates front "wings" projecting on the sides to facilitate transfers.




Seat cushioning:

Seat pressure-map Various foam densities were tested with a pressure-map. The results indicated that low-pressure readings were dependent not only on the amount of padding but also in using a softer density of foam under the ischial tuberosoties around the periphery of the inner seat area versus a harder density foam for the rest of the seat.



Swing-away armrests:

Swing-away armrests Lockable pivoting and swing away armrests, capable of holding patients weighing upward of 100 kg were designed. In the locked position, users can latch under them and pull-up without fear of unlocking. A lever release mechanism was developed to lock and unlock the armrests. Long armrest pads were used to provide increased resting surface area for the arms and elbows.



Footrest design:

Contoured and adjustable footrest Development started with designs that held the entire foot, leading to a deep heel-cup contoured design to fit the bottom of the foot with all surrounding edges rounded and smooth. A hole is included for water drainage when showering.



Footrest adjustment:

The ability to adjust footrests in order to match the user’s leg height is critical in establishing a good seating position. In developing the new footrests a lever handle was selected to easily lock/unlock/raise and lower them.




An open-weave nylon mesh was selected to facilitate water flow-through in showering.


Box 2. Key components for body support



Typical wheelchairs are equipped with 61cm diameter wheels and 1.9 cm diameter metal pushrims or handrings. Because that wheel height interfered with patient side transfer 55 cm diameter wheels were selected. Hand ergonomic data was used to develop new pushrims to increase grasping in wet environments and propelling. Ten wheelchair users participated in a preference study and selected 3,5 cm as the preferred diameter which was then produced in aluminum and rubber coated.


Clinical evaluation and collaboration with manufacturers

The prototype evaluation involved actual clinical use of the wheelchairs with 20 patients and 20 caregivers at the Milwaukee and Tampa VA Medical Centers. Additionally, a post trial questionnaire was used to rate the wheelchair’s features regarding toileting, showering, seating, transferring, folding-unfolding and self-propelling.


The new wheelchair was found to fit conveniently in shower stalls and over toilets, to improve showering and toileting via the many places available for patients to grasp and hold. The wheelchair held the user in a safe position and provided a wide and comfortable seat. Finally the coated larger size pushrims/handrings faciltated self-propelling especially when wet.


Wheelchair publicity flyerThe designers collaborated with several wheelchairs manufacturers during design development. This collaboration was very useful for marketing and manufacturing advice. The US Department of Veterans Affairs patented the many new features of the wheelchair (US Patents # 6,176,508; 6,623,022 and 6,604,750 B2) and licensed them to ActiveAid Inc. of Redwood Falls, MN. It is available as the AdVAnced Folding Shower/Commode Chair model # 922.

Author : Pascal Malassigné, M.Sc.
Adapted from : Malassigné, P., Nelson, A.L., Jensen, R.P., Cors, M. (2001). “Design, development, evaluation, patenting and licensing of new shower-commode wheelchair. A case study in universal design research.” Proceedings of the 2001 IDSA Education Conference.
This research was supported by the Rehabilitation R&D Service of the US Department of Veterans Affairs, Washington DC.



  • American National Standards Institute (ANSI) /Rehabilitation Engineering Society of North America (RESNA). Wheelchair standards. Washington, DC.: RESNA Press; 1990.


2 commentaires

  1. luis dit :

    can you send mee the price for 30pç this model.
    Portuguese company

  2. Gail dit :

    Your design is optimal. Good luck. Been looking for specific design for client. How close are you to market?

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