Module 7 - Postural Interventions
Key principles to postural interventions
1. Postural stability
Posture is affected by the interrelated nature of the lower limbs, pelvis, trunk, upper limbs, head and neck. Postural stability is required to facilitate optimal function and to provide safe and comfortable seating.
Principles of pelvic stability
- As noted by Waldemar Karwowski (2006), a seated person supports 32% of their body weight through their feet and legs. Therefore adequate support of the feet and legs is needed for the wheelchair user to stabilize the position of the pelvis. This in turn facilitates stabilization of the trunk, leading to improved function of the upper limbs and posture of the head and neck.
- An unstable trunk requires the use of the upper limbs for stability, thus reducing functional reach.
- A stable pelvis provides the base of support for functional reach and allows independent changes in posture
- Gravity is a constant force that aids or opposes movement in a support system (e.g sitting in a slumped position promotes sliding versus sitting in a tilt-in-space system that utilises gravity to support body weight)
- Material properties of the support surface, such as stiffness and friction, impact on postural stability. Read more on materials properties:
- Wheelchair Cushion Differences, Stephen Sprigle, Ph.D., PT.Spinlife.com, accessed 2008 http://www.spinlife.com/spintips/details/k/Wheelchair-Cushion-Differences/a/107/c/89
- Terms and definitions related to support surfaces, National Pressure Ulcers Advisory Panel 2007, accessed 2008 http://www.npuap.org/pdf/NPUAP_S3I_TD.pdf
- Depending on the client's level of balance and function, wheelchair acceleration, deceleration, centrifugal force and uneven terrain will influence stability if the client is inadequately supported in these planes. Effective interventions will therefore consider anterior, posterior, medial, lateral, superior and inferior forces to improve stability.
- Postural stability should support dynamic function and not reduce voluntary and functional movement, with the exception of transport requirements and safety considerations.