Customized Wheelchair Seating Fit for Physiology

How custom wheelchair seating and positioning affects the body’s functionality.

by Kirsten Davin, OTD, OTR/L, ATP, SMS

customized seating has a significant impact on the ability of wheelchair users to be as independent and participate in daily activities as possible. It is not surprising that there is a wealth of literature on the relationship between wheelchair positioning and daily activities. Daily function is important to our roles and responsibilities. However, the physiological impact of wheelchair seating and position is often overlooked.

There are both high-tech and low-tech options in the customized wheelchair seating market. Low-tech options include foam-in place fabrication or manufactured custom-contoured components. High-tech options can incorporate digital imaging and pressure mapping to map the wheelchair users’ anatomy for as accurate a fit as is possible.

The availability of wheelchair seating and positioning products has increased in recent years. However, the ability of therapists or equipment suppliers to stay abreast of all the custom seating options and determine which custom seating option is preferred by the client has also grown.

Addressing Asymmetries In Customized Wheelchair Seating

Therapists must consider the asymmetries of clients when deciding whether to use complex seating or customized wheelchair seating. Asymmetries can be either correctable or not. A correctable asymmetries occurs when a client can return their asymmetry to a neutral position and improve its functionality. Non-correctable asymmetries occur when the client is unable to adjust or fix their asymmetry. In many cases there is no clear definition of a correctable or noncorrectable asymmetry. Clients may present with asymmetry which is correctable up to a certain point, but becomes non-correctable when the return to midline is near. The ability to delineate between the two classifications of asymmetries is imperative, as the type of asymmetry present–correctable or non-correctable–will determine the course of action in the development and application of custom seating.

Custom seating can often be implemented with ease and you will see the functional benefits. Sometimes it is more difficult to identify physiological outcomes. Let’s look at the physiological outcomes that are related to seating and position.

Respiratory performance and Pulmonary capacity

Imagine yourself in a sitting posture. If you tilt your pelvis backwards, demonstrating posterior tilt, then your torso will be in a forward-flexed position. If the posterior pelvic tilt is excessive or combined with trunk and core weakness, it could affect your diaphragm over time.

If this occurs in a wheelchair’s seat system, a physical or occupational therapy may recommend an accessory device to be used on the wheelchair. This could include a pelvic or anterior trunk support that will position the trunk as neutrally or functionally as possible. A marked improvement in respiratory performance is usually a sign of improved trunk neutrality. Sometimes a therapist will be able to visually identify this, but other times you’ll have to use a pulse-oximeter or another pulmonary test to indicate improvement.

Head-and-Trunk Control for Eye Gaze

In the example shown above, after intervention to support the torso many clients will experience an improvement in head control and eye gaze. Sometimes, clients will require an additional product to provide the necessary head support, such as a anterior head support, to prevent the forward flexed head position. If the client is able achieve adequate head and trunk controls, their eyes will be in a direct or improved line of sight with objects used for activities of daily life, mobility paths, and social engagement.

Imagine how difficult it would make it to talk to someone across the table if your head were in a forward-flexed position. The client’s customized seating system and the head and trunk control are crucial to promoting neutral and functional eye gazing. This is particularly important for clients who self-propelling wheelchairs or those using powered mobility.

Digestive performance and Swallow

As noted above, forward flexion of the trunk due to a posterior pelvic tilt, or an ill fitting seating system can also negatively impact one’s digestion. A poor sitting posture may cause digestive issues, such as an imbalance in stomach acid, malabsorption, and irritable-bowel syndrome. Proper pelvic alignment and torso positioning can promote digestive and bowel health.

Correct cervical and torso position promotes a functional, healthy swallow. This is in addition to the digestive performance mentioned above. Consider, for instance, a client seated in a wheelchair with a positioning system which places the neck in a slight extension. This extended position can reduce the user’s ability to swallow and increase the risk of aspiration for some clients. Positioning that takes into account the client’s needs for an effective and efficient swallow can reduce the risk of pneumonia and other respiratory concerns.

Skin Protection and Breakdown Prevention

Asymmetry in a seating system can lead to uneven pressure distribution and skin breakdown, which can result in pressure injuries. A client with pelvic obliquity is at risk of skin breakdown due to pressure under the low side pelvis. A client with a posterior pelvic tilt and forward flexion of their trunk is at risk of experiencing skin breakdown in the sacral or the coccyx area. The use of an adjustable wheelchair with pelvic height adjustment can help neutralize pelvis in cases where the obliquity is correctable and accommodate in non-correctable cases to avoid pressure injuries, skin breakdown, and other complications.

Current Asymmetries & Deformities

There are many seating and positioning options that can help slow or prevent the progression of any asymmetries that a client might be experiencing. If the client has a correctable lateral trunk flexion and a pelvic tilt, an obliquity pillow along with any lateral supports needed can help correct the current asymmetry.

If the client does not receive any treatment, it is likely the pelvic obliquity will continue to progress, pulling the lateral flexion with it. This would create a greater asymmetry, and over time, increase the chances that the asymmetry will become a non-correctable problem. This would also likely lead to other issues, such as skin integrity concerns, respiratory ramifications or pulmonary ramifications.

As soon as you identify the problem, it is best to start correcting and addressing any deformities or asymmetries. Early identification and effective intervention are the keys to a successful outcome.

Muscle Tone

During the evaluation and seating process, altered muscle tone is a common issue. Altering muscle tone can affect a person’s ability to perform functional tasks and interact with their wheelchair.

Hypotonia, which is often a symptom of cerebral palsy or muscular dystrophy or spinal muscular atrophy, can make it difficult for a wheelchair user to maintain an upright, functionally-independent position while seated. Wheelchair cushions that have increased contouring, or use of laterals or hip guides, or medial supports and more, may help clients with hypotonia maintain independence and address or improve the other physiological considerations listed above. The tilt-in space feature of a manual or a power wheelchair base may also help users with hypotonia by allowing gravity assist in maintaining stability.

Hypertonicity–common in cases of cerebral palsy or with clients who have experienced acquired brain injury–presents as increased muscle tone, with joints in the arms and legs that are quite difficult to flex or extend. Therapists may recommend wheelchair cushions with contours that wrap around the trunk or lateral thoracic support to better support the trunk, and improve other physiological functions.

Upper Extremity Function & Daily Living Tasks

A good seating and positioning system will promote the proper function of the upper extremities, such as swallowing, digestion, and breathing, while also allowing for upper extremity movement. They can improve the user’s daily activities, which promote physiological function, mental well-being, and well being, as well as allowing them to perform exercises. Exercise and movement can also help improve and maintain other physiological functions, such as respiratory capacity and performance.

The goal of wheelchair positioning and seating is to help the user achieve a neutral and functional position in order to maximize their abilities. The seating system should also aim to protect the skin integrity and address any other physiological considerations. This is because clients’ health and well-being are dependent on their ability to function effectively. RM

Original Blog: https://rehabpub.com/seating-positioning/custom-seating/customized-wheelchair-seating-fit-for-physiology/