Development of advanced personalized modular pressure relief seating cushion systems: Testing and user evaluation

Pressure injuries are a significant secondary complications for many individuals with reduced mobility,
including elderly Veterans and those with spinal cord injury (SCI). Core assistive technology for persons
with limited mobility includes a wheelchair seating system, comprising both a wheelchair and an
effective pressure relief cushion. All wheelchair users are at some increased risk of pelvic region
pressure injuries while sitting. Numerous studies have shown that although no one cushion can meet
every user's needs, pressure relieving cushions are a critical component in all wheelchair seating
systems to maximize function for individuals with mobility restrictions and decrease the risk of pressure
injury development. An effective cushion prevents tissue breakdown, promotes postural stability and
increases overall sitting tolerance.
Preliminary work investigated a range of novel low-cost dynamically responsive materials developed for
the non-medical market and which showed potential for use in seating design. A key aspect of the
modular cushion's design is its ability to be fitted and customized for each user using a cushion fitting
algorithm (CFA). The modular array thus optimizes pressure distribution over the cushion surface while
the user is sitting. Using the CFA, each cushion can be personalized for the user to optimize interface
pressure distribution and maintain seated tissue health.
The current project will provide next-generation development and user evaluation of a low-cost
advanced modular pressure relief cushion and fitting algorithm, building on the previous support from
VA. The first generation modular cushion was designed for power wheelchair users, the second
generation will be lower weight and also suitable for manual wheelchair users. Low cost compressible
SquishINS inserts will be additively manufactured using commercially available silicon by modified
desktop Makerbot Replicator printers (StrataSys, Brooklyn, NY). Pre-clinical benchmark evaluation will
be carried out using ISO 16840-2 testing standards. Cost analysis will ensure that the next- generation
modular cushion continues to apply value-driven principles. A clinical pilot study of 30 Veterans who are
full-time wheelchair users will be carried out using a repeated measures clinical study design, with
study participants as their own controls. `Pre-baseline' seated interface pressures will be assessed with
study participants sitting on their own cushions and pelvic region skin checks carried out by the study
Research Nurse. All participants will then receive customized modular cushions fit to the user using the
CFA to create a personalized cushion insert layouts. Participants will be randomly assigned to Group A
or Group B using a modified randomization scheme. Group A participants will first use a gel ball fitted
cushion for 2 weeks during all daily living activities while seated in their wheelchair followed by use of a
SquishINS fitted cushion for 2 weeks. Group B will first use the SquishINS fitted cushion then a gel
ball fitted cushion. Seated interface pressure distribution will be obtained with the fitted cushion at the
beginning and end of each test period. A dual temperature and humidity sensor placed in the cushion
will enable continuous monitoring of microenvironmental status during use for download at the end of
each test period. The study Research Nurse will also repeat the pelvic region skin check and
participants will complete a questionnaire based on the QUEST 2.0 user satisfaction instrument. All
responses will be documented as part of the QS/DC program.
Our pre-clinical development and user evaluation will provide a strong foundation for translation of
personalized low-cost high-performance modular cushions for effective seated pressure redistribution in
wheelchair users.

Grant Number: 5I01RX002434-08
NIH Institute/Center: VA
Principal Investigator: KATH BOGIE