Understanding Dynamic Seating Systems
Did You Know?
Dynamic Seating can be Beneficial for Persons Exhibiting Forceful, Repetitive Patterns of Movement
Adaptive or therapeutic seating is seating that has been modified to provide additional postural support to individuals who, due to impairments in their neuromuscular system, are unable to sit with a well aligned posture. Seats may be stationary, mobile (on a base with casters) or part of a wheeled mobility device such as an adaptive stroller or wheelchair. Appropriate seated positioning aims to have a beneficial effect on postural stability and alignment, muscle tone, reflex activity, prevention of deformity, maintenance of skin and tissue integrity, and optimizing function. Seating systems can include head support, trunk support, pelvic/hip support and support for legs and feet through contoured cushions, supportive pads, straps and harnesses and even features such as reclining backs and tilt-in-space.
What is Dynamic Seating?
A concept relatively new in adaptive seating and meeting with enough success that it is being offered more widely by manufacturers of adaptive equipment, is Dynamic Seating. Dynamic Seating is defined by Occupational Therapist Michelle Lange of Seating Dynamics in her 3-part Webinar Series on Dynamic Seating as the movement which occurs within the seating system and/ or wheelchair frame in response to intentional or unintentional force generated by the person using the seat. Dynamic components absorb force and return energy to assist the client back to the starting seated position. Dynamic seating systems facilitate the achievement and maintenance of a well aligned seated posture by allowing movement and assisting the person back to the original starting position. Limited research evidence available on dynamic suggests several positive therapeutic benefits.
Who benefits from Dynamic Seating?
People with extreme muscle tone, people who seek out movement such as rocking and people who have voluntary or involuntary extraneous movement patterns that need to be addressed. People with repetitive voluntary or involuntary movement patterns, especially when movement is performed with a high degree of force, are most likely to benefit from dynamic seating. People with Cerebral Palsy especially those who have dystonic movement patterns. Dystonic cerebral palsy, also referred to as dystonia, is marked by involuntary muscle contractions and movements that affect either one part of the body or the entire body. People with other neurological diagnoses such as traumatic brain injury, multiple sclerosis, spinal cord injuries and strokes can also benefit. People with developmental disorders such as autism spectrum disorder (ASD) may also engage in perseverative movement patterns such as rocking and they can also benefit from dynamic seating.
Where does the movement occur in the seat?
Movement can occur at the hips, legs, and/or head using the following components alone or in combination. Each component captures movement separately.
Dynamic Rocker Back – The pivot point for movement aligns with the body’s natural pivot point for movement at the hips. It captures intentional and unintentional forces of forward and backward motion- rocking and extensor tone/extensor thrusting. Allowing this movement diffuses abnormal tone or allows rocking (perseverative self-stimulation) for the person who is seeking it.
Therapeutic Benefits of a Dynamic Back:
- To diffuse force that could otherwise lead to client injury, loss of equipment alignment or breakage, decreased sitting tolerance, increased agitation, decreased function, energy consumption, and escalating muscle tone.
- To allow movement to provide sensory input, increase alertness, and decrease agitation.
- To improve postural control, stability and function. For example, a dynamic back can help facilitate a person’s self-propulsion of their wheelchair.
Dynamic Footrests - Movement can occur in multiple directions.
Therapeutic Benefits of a Dynamic Footrest:
- Telescoping footrest- up and down movement of footplate
- Knee bending and straightening
- Ankle plantarflexion/ dorsiflexion (pointing toes towards floor/ceiling)
Dynamic Head Support - movement can occur in multiple directions
Therapeutic Benefits of a Dynamic Head Support:
- Single Axis- neck forward flexion and extension (yes/ no motion of head)
- Multi-directional also allows rotation (turning of head)
Dynamic headrests do not allow hyperextension of the head and neck.
Most dynamic seats will offer an adjustable range of resistance in the movable components. Movement is accomplished using springs, elastomer or hydraulics. Force from the person compresses the component, which absorbs the force, and stores it as energy. The stored energy assists the person back to upright as forces are reduced. If the resistance is too firm the person will be unable to activate the available range of movement. If the resistance is too little, the stored force may not be enough to return the person to the starting position.
Most dynamic seats provide a mechanism to lock out the movement component. This can be important when transporting the person in a mobile dynamic seating device, such as a wheelchair or adaptive stroller, in a vehicle. Also, when a person is moving across rough terrain in a mobile dynamic seating device. When a person is engaging in activities of daily living that require stability of the seated posture such as feeding and using a communication device, it may also be beneficial to lock out the movement component of the dynamic seat.
It is of significant importance to note that dynamic components absorb extreme client forces and return energy to assist the client back to the original starting position without loss of the original starting position. Shearing forces are minimized in dynamic seating systems. Pressure distribution is enhanced.
Research supports the following benefits of Dynamic Seating:
- Protects the wheelchair user from injury
- Protects wheelchair and seating hardware from malalignment and breakage
- Inhibits/diffuses extreme muscle tone and abnormal posturing
- Increases sitting tolerance and compliance
- Enhances vestibular and proprioceptive input
- Facilitates active range of motion
- Improves alertness compared to static seating systems
- Decreases agitation
- Decreases fatigue
- May improve strength and postural control
- Reduces forceful active full body extension patterns/ extensor thrusting
- Reduces energy consumption
- Can optimize function
Dynamic Seating is a current trend gaining traction in the area of therapeutic adaptive seating. Though more studies are needed to solidly support evidence based practice of its use, the limited research evidence available suggests this concept in seating may be very beneficial to people who have forceful, repetitive patterns of movement while sitting.