biodex SIT2STAND 950-560, Operation & Service Manual

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BIODEX MEDICAL SYSTEMS, INC. © 2015 1
1. Introduction
Theory of Operation
It is important for the therapist to know and clearly understand the normal kinematic
movement components of the sit-to-stand sequence.
The progressive steps of the sit-to-stand motion, from a seated position, are as
follows:
o
Phase one - Flexion momentum - Anterior pelvic tilt, lumbar and thoracic
extension
o
Phase two - Momentum transfer - Trunk flexion, hip flexion, head extension and
maximal dorsiflexion
o
Phase three – Extension - Lumbar and thoracic extension, scapular depression
(This movement continues until the center of mass is directly over the base of
support.)
o
Phase four – Stabilization – Regaining postural stabilization. Starts with terminal
hip extension and ends with full extension of trunk and hips (Optimal end
position is 0° hip and trunk extension.)
Fig. 1.1 The four phases in the sit-to-stand sequence.
The functional task of being able to arise from the seated position is necessary for most
activities of daily living (ADLs). Patients may have a multitude of impairments such as
decreased muscle strength, sensation/proprioception issues, and visual perceptual
problems that lead to limitations in their ability to perform even the most basic aspects
of the sit-to-stand sequence. These impairments can lead to fear of movement,
increased anxiety, and limited trust in the therapist, making it difficult for patients to
learn the components of sit-to-stand. In the cases of elderly or severely deconditioned
individuals, when the inability to perform this basic skill is lost it can lead to impaired
functioning and independence with mobility as well as with ADLs.