Wheelchair Seating Research Articles

Seated Lumbar/Pelvic Alignment

It has been postulated that loss of voluntary trunk stability, combined with the posture imposed by the configuration of the wheelchair seat, biomechanically necessitates that a person with diminished trunk control assume an abnormal sitting posture. This posture is characterized by a long, "C"-shaped kyphotic thoracolumbar spine, an extended cervical spine, a flattened lumbar spine, and a posteriorly tilted pelvis. If lateral trunk deformities are present, trunk imbalance and pelvic deformities in the coronal (frontal) plane can exist. This study has investigated the spinal/pelvic postural alignment of a limited sample of seated spinal cord-injured people and compared the results to a similar sample of able-bodied individuals seated in the same standardized positions. The results suggests that there are distinct differences in the spinal/pelvic alignment between the two study groups. These differences and the movements that take place in the pelvic structures during active wheelchair sitting have implications relative to pressure sore prevention and postural management.

Dynamic interface pressure between seated users and their wheelchairs

Little is known about the dynamic pressure distribution changes that take place on the sitting surface of a wheelchair while one propels oneself on a level surface. An understanding of these dynamic pressure changes may influence the design of wheelchair seat cushions to minimize pressure sores in wheelchair users. This research investigated the dynamic interfacial pressure changes on the seated wheelchair user during short bursts of locomotion on a level surface. The pilot project included only able-bodied subjects who sat in sling-seat wheelchairs. Pneumatic bladders arranged in a flexible grid matrix (50 elements covering a 7.5″ × 15″ area) were instrumented with miniature piezoresistive pressure transducers and placed between the user and the wheelchair seat. One half of the subject/seat interface was instrumented: one-half-inch-thick foam covered the remaining half of the seat. Dynamic pressure distribution in the left and right halves was measured in separate trials for every subject. Each sensor element was sampled 10 times per second during the time it took the subject to traverse approximately 25 feet from start to stop. A trial lasted 5.6 seconds on average. The greatest shift in center of pressure observed for any trial was 3.15 inches. The lowest, static, and highest average pressures obtained were 14.2 mmHg, 27.8 mmHg, and 36.5 mmHg, respectively. The lowest, static, and highest maximum pressures were 42.0 mmHg, 135.0 mmHg, and 178.8 mmHg, respectively. There was no significant difference in location between the lowest and highest maximum pressures. The sizes of the buttock area in which pressure exceeded 35 mmHg were determined for smallest area, static, and largest area conditions. These were 2.25 sq.in., 27.0 sq.in, and 47.25 sq.in., respectievly.

Wheelchair seat comfort for the institutionalized elderly.

Studies have reported many wheelchair problems faced by the institutionalized elderly. Because knowledge is limited regarding seat comfort in general and for the nursing home population in particular, we elected to investigate seat comfort in order to gain insight needed to solve seat discomfort problems. This study's primary objective was to identify quantifiable indicators of seat comfort. Seat comfort was investigated in relation to peak sitting pressure, asymmetry of sitting pressure distribution, and seat cushion type. Fifty nursing home residents who were able to reliably rate the comfort of their wheelchairs were surveyed. The survey consisted of several questions regarding wheelchair seat comfort, wheelchair use, and functional and cognitive abilities. Measurements included peak sitting pressures and parameters of sitting posture. This study failed to identify robust indicators of seat comfort. It failed to confirm the hypothesis that higher peak sitting pressures correspond to greater discomfort. No relationship was found between the asymmetry of sitting pressure and reports of seat discomfort. Although we were unsuccessful in achieving statistically significant results, we did identify seat comfort indicators that are not only statistically significant but are also of practical clinical usefulness. Further research with additional subjects is required to identify cushions that are both comfortable and pressure relieving.

A Survey of Wheelchair Seating Problems of the Institutionalized Elderly

This study attempted to define and quantify the need for appropriate seating for elderly nursing home residents. A questionnaire was administered to 200 randomly selected nonambulatory elderly residents living in six Memphis area nursing homes. The study results supported previous findings that many nursing home residents have seating and mobility problems. Of the 139 wheelchair users analyzed, 112 (80%) experienced at least one problem related to discomfort, hindered mobility, or poor posture. Thirty-four percent of the residents had at least one problem considered to be severe. In most cases our respondents' seating and mobility problems could have been solved by the tailored application of presently available technologies.

Pushchairs

Pushchairs for adults are used by two distinct groups: the high dependency users who cannot walk or use a self-propelling chair and the occasional users who may be able to walk indoors but are unable to walk significant distances outdoors. In the past, both disparate groups were provided with similar wheelchairs described as Model 9 or Model 10 in the United Kingdom. For the high dependency user the wheelchair may be individually adapted to accept specialized supportive seating and pressure relief cushions. The standard wheelchair without adaptation is supplied to the occasional user. For disabled children, the UK wheelchair service provides about 1200 pushchairs and buggies. About 400 of those are the more specialized type such as the Avon, while the rest are standard children's buggies, openly available at a High Street shop. The continued free supply of the standard buggy through the UK Wheelchair Service is questionable. A recent survey carried out by the UK Wheelchair Service showed that prescribers were not aware of the importance of lightness., foldability and appearance to parents and carers and conversely that parents often did not understand the necessity for supportive seating. The prevention of deformities in children by providing correctly supportive wheelchair seating is accepted. The Disablement Services Authority in the UK is investigating the possibilities of producing children's wheelchairs that will satisfy the requirements of user, parent and prescriber.

New wheelchair seating system

New wheelchair seating system

Sitting forces and wheelchair mechanics

The effects of back angle and leg height on sitting forces in a wheelchair were studied, using a force plate mounted on a wheelchair seat. Readings of both normal force (perpendicular to the seat) and shear force were measured while the chair's back angle and footrest height were changed. Pressure under the ischial tuberosities was also measured during the footrest height adjustments. Five normal subjects sat directly on the plate as well as upon ROHO and Jay cushions placed on the force plate. Returning the back to the upright position after a recline caused the normal force (+/- SD) to increase 5.4 +/- 2.5, 9.5 +/- 4.0, and 10.0 +/- 2.3 kg for the hard surface, Jay cushion, and ROHO cushion respectively, while shear at the plate increased to 5.1 +/- 2.2, 11.6 +/- 2.6, and 12.3 +/- 2.7 kg for the hard surface, Jay cushion, and ROHO cushion respectively. Leaning forward (away from the back) caused all the forces to return to measurements close to the starting values. The results suggest that the wheelchair user should momentarily lean forward after a recline to reduce undesired forces. If a cushion with firm thigh support is used, ischial tuberosity pressure can be reduced by lowering the leg height as much as possible, which causes a levering action by lifting the pelvis.

Improvement of seating comfort due to a new wheelchair seating system

Improvement of seating comfort due to a new wheelchair seating system

Improvement of seating comfort due to a new wheelchair seating system

Improvement of seating comfort due to a new wheelchair seating system

Evaluating the client with physical disabilities for wheelchair seating.

Positioning through wheelchair seating allows many severely physically disabled individuals to use their motor skills to access technical aids. In the last 10 years, many products relating to wheelchair seating have been developed and are now being used. This article outlines evaluation and prescription guidelines that lead to the accompanying recommendations for seating. Categories for matching disability type/severity to seating methods are presented.

Microprocessor-based weight shift monitors for paraplegic patients.

The prevention of pressure sores for patients with spinal cord injuries includes pressure relief through the patient shifting position and, thus, weight. We have designed a microprocessor-based device to mount on the seat of a conventional wheelchair. This device has applications in hospital rehabilitation programs for improving patient care and in research to study the cause and prevention of pressure sores. It can use audible alarms, which can be disarmed, to train patients to regularly shift weight. The device stores in its memory data on the interval between and the duration of weight shifts. The contents of this memory can be transmitted to a laboratory microcomputer system and displayed in tabular, graphical, or histogram formats. This device is more versatile than previous timer-based systems, not only because its timer and alarm parameters easily can be reprogrammed, but especially because it can store and play back detailed data on the patient's performance. The device is powered by rechargeable NiCad batteries, which can last several days without recharging.

Development and evaluation of a universal contoured cushion.

A new wheelchair seat cushion has been developed which reduces the ischaemia producing forces and redistributes them to the more tolerant areas of the posterior thighs and lateral gluteal muscles. The cushion is fabricated of foam materials and designed to stabilise the pelvis and promote proper spinal-pelvic alignment. Pressure measurements were recorded at the skin cushion interface for 66 subjects while seated on the cushion in their own wheelchair. The cushion was considered effective if maximum interface pressures recorded were: coccyx: less than 20 mmHg, ischii: less than 65 mmHg, trochanters: less than 70 mmHg, and posterior thighs: less than 80 mmHg. The cushion was considered ineffective if the interface pressure at any one location exceeded these criteria. The cushion was found effective for 52 of the subjects. The cushion was more effective (90 per cent versus 58 per cent) for subjects without certain skeletal deformities (pelvic obliquity, bony resections). Eighty-three per cent of the respondents who were followed on the cushion reported that they preferred the cushion to their previous cushions with improved posture, balance and comfort being the most commonly cited reasons. This study has shown the cushion to be a preferred alternative to other commercially available wheelchair cushions for those who are paraplegic.

Fully contoured seating for the wheelchair-bound patient with neuromuscular disease. Suggestion from the field.

Current wheelchair seating does not fully correct or accommodate severe deformity in patients with neuromuscular diseases complicated by spinal curvature.1,2 We developed a custom-molded seating* system that inhibits incipient scoliosis and that fully accommodates established truncal deformity in both coronal and sagittal body planes (Figure). An outrigger can be added for additional stability if the patient or therapist requests it. The patient is first positioned to obtain maximal spinal correction. A vacuum-molding technique, using an aluminum shaping-frame and a latex bag filled with polyethylene beads (based on the concept of the bean-bag chair), provides a template. The mold is used to fabricate both a seamless, vinyl-covered, polyurethane foam-padded seat and a back rest. The cost of the seating assembly is approximately $1,200. The custom-molding system permits control over corrections in seating position through body-chair congruence.…

A hydraulic seat-rise wheelchair.

A hydraulic seat-rise wheelchair constructed for a patient experiencing severe difficulty getting into and out of a wheelchair is described. The seat-rise mechanism, activated by a hydraulic cylinder, is constructed to locate within a wheelchair frame replacing the seat and back of a normal manual wheelchair. Patient control of the lifting and lowering feature is maintained by controls fitted to the arm of the wheelchair. A wheelchair of this design is most suitable for use by patients who, by virtue of their disability, require it to achieve greater independence.

THE CHICAGO INSERT

Scoliosis is a complication of wheelchair confinement in Duchenne muscular dystro­ phy. 4 Such curves are rapidly progressive and are convex toward the side of the domi­ nant hand because the patient usually leans toward the nondominant side to support the dominant arm. 3 A variety of external spinal containment systems have been described which retard the rate of scoliotic progression by maintaining the spine erect. Wilkins and Gibson, studying 62 wheelchair-confined Duchenne dystrophics, noted that al though many developed marked scoliosis and kypho­ sis, those with hyperextended spines and rig­ id paraspinal contractures had comparatively little lateral curvature. 5 Locking of vertebral facets in exaggerated lordosis apparently in­ hibits the development of scoliosis. Wilkins and Gibson recommend orthotic manage­ ment of wheelchair-confined patients to keep the pelvis level and the spine extended. This can be accomplished with a firm wheelchair seat and either circumferential or three-point torso support, preferably fabricated from orthoplast or Pelite-lined polypropylene or polyethylene. Alternatively, a spinal con­ tainment orthosis in the form of a modified wheelchair seat may be used. 2 This method features a fiberglass shell, lined with customcarved polyurethane foam upholstered with a modified urethane foam and a tricot double-knit covering. The patient's pelvis is snugly fitted and his thoracolumbar junction extended. The lumbar lordosis thus created is bolstered by the backrest, which also incor­ porates lateral flanges to support the sides of the chest. To further encourage lumbar ex­ tension, the backrest is inclined backward 15 degrees. Although offering a viable option in the prevention of scoliosis in wheelchairconfined Duchenne dystrophies, cost and availability of this system limit its wide ap­ plication.

Oscillating wheelchair seat for prevention of decubitus ulcers

A wheelchair seat designed to prevent the occurrence of decubitus ulcers has been constructed and tested. The rear section of the seating surface is periodically lowered to allow a reduction in pressure for the highly stressed tissue underneath the ischial tuberosities. Several parameters in the seat can be easily adjusted to accommodate the needs of different individuals.

The function of the rump in relation to sitting and the Keane Reciprocating Wheelchair Seat

There is no appliance which will prevent decubiti in the immobile patient. Rump function in relation to man is discussed. Body weight is carried on the skeleton and transmitted to a natural surface, i.e. the ground via weight bearing superficial bony prominences. These protect vital structures: muscle, urethra, nerves, arteries from the effects of pressure. Convential seat appliances are unscientific, and seek to relieve pressure on the skin in the area of the ischia by transferring pressure to the soft tissues. Consequently, the physiological condition is reversed, the skeleton and body weight is supported on vital tissues. This leads to serious and deep necrosis which starts within the warm ischaemic muscle survival time which is much shorter than survival time for skin.It would appear that there is no safe method of preventing decubiti except the normal physiological means: mobilisation of the patient.The Keane Reciprocating Wheelchair Seat consists substantially of an outer support means of conventional toilet seat shape and an inner mechanically operated central seat which lifts the patient in a physiological way on the ischia once every 9 min, thus there is adequate transfer of weight from one large area of the buttocks to another. Therefore prolonged ischaemia is avoided. It has been observed that under restoration of adequate mobility ischial decubiti will heal. Intermittent pressure produced by body weight is normal for tissue and repair by cicatrisation. Consequently, bedrest with interruption of occupation is not necessary in the treatment of ischial sores.

Wheelchair seat board for use with spica cast.

Journal Article Wheelchair Seat Board for Use with Spica Cast Get access Irene A. Towle Irene A. Towle 1Mrs. Towle is a clerk in the physical therapy department, Long Beach General Hospital, Long Beach, CA 90806 Search for other works by this author on: Oxford Academic Google Scholar Physical Therapy, Volume 53, Issue 1, January 1973, Page 37, https://doi.org/10.1093/ptj/53.1.37 Published: 01 January 1973