Submitted by: Jeremy Nelson PT
Component 2.0 – Standing Unsupported
This component is seeking to learn more about how well the patient is able to maintain the center of gravity over their base support in an elevated position. As the center of gravity rises above the base of support there is an increase in the kinetic energy. New forces are imposed on the structure of the body, and the body needs to respond to control the dynamics. So the static standing is more challenging for the neuromuscular system than being seated. In the seated position, control of the center of gravity is enhanced by a larger BOS, within the base of support that includes the pelvis, femurs and feet.
In addition were looking at the quality of the passive range of motion within the skeletal structure to attain extension as well as the extensors of the body to resist the pull of gravity. The human skeleton has a few tricks to assist with maintain full extension; however it requires adequate passive range of motion into extension and adequate length of the flexors to attain this. Thus an assessment of posture is worth adding to these observations. Knees that are unable to meet full extension and take advantage of the screw home mechanism may be caused by knee flexion contracture or hip flexion contracture. Being that the scoring is time dependent, the endurance factor also leads to a better understanding of the conditioning of LE and posture efficiencies.
This component BOS is a symmetrical stance. Within the component the sub-components allow for an opportunity to change the amount of support in order to up towards the ability to stand safely for two minutes. To score 0 you must unable to stand for 30 seconds unsupported. And to score one point there is a need for several tries to stand 30 seconds unsupported. Although not part of the scoring, the clinician may investigate within this score to see what impact single upper extremity support going from bilateral upper extremity support has on the standing balance.
There are a number of reasons why patient would not be able to stand unsupported. The most common is the position of the knees and hips remaining in a flexed position which increase the amount of mechanical strain on the system. 0° hip extension and knee extension allow for the joints and bones to support the standing. When the hips are flexed and unable to extend to neutral the internal rotation of the femur is lost. As a result the screw home mechanism in the knees is not available, thus reducing stability of the knee. This also burdens the patient as they must to do a lot more work during standing. Instead of the skeletal structure contributing to maintaining the COG above the symmetrical base of support, instead anterior chain is excessively used as this puts the COG near the posterior aspect of the BOS.
The symmetrical standing posture is not typically used in most functional activities, as the body is better positioned in an asymmetrical stance to move. With this component asymmetrical stance can be enhanced and the overall function of the patient improved.