Increased Seat Dump Angle in a Manual Wheelchair is Associated with Changes in Thoracolumbar Lordosis and Scapular Kinematics during Propulsion

Arch Phys Med Rehabil, 2017 · DOI: 10.1016/j.apmr.2017.02.014 · Published: October 1, 2017

Spinal Cord Injury Assistive Technology Biomechanics

Simple Explanation

This study investigates how changing the angle of a wheelchair seat affects posture and shoulder movement during wheelchair use in people with spinal cord injuries. The researchers looked at two different seat angles and measured spinal curvature and shoulder motion. The study found that increasing the seat angle reduced the natural curve in the lower back and altered the movement of the shoulder blade, especially in individuals with spinal cord injuries higher up the spine. Interestingly, the shoulder joint itself wasn't significantly affected by the seat angle, suggesting that the risk of shoulder impingement might not change with this particular adjustment.

Study Duration

August 2014 through April 2015

Participants

21 individuals with spinal cord injury

Evidence Level

Not specified

Key Findings

1
Participants had significantly less lordosis in the 14° condition for all propulsion events.
2
Scapulothoracic internal rotation was increased in the 14° condition at SP and MP
3
No glenohumeral rotations were significantly different between the conditions.

Research Summary

The study quantified and compared spinal curvature and scapulothoracic and glenohumeral kinematics throughout the MWC propulsion cycle while individuals with SCI were seated at 2 different seat dump angles (0° and 14°) with a vertical backrest. For individuals with SCI, spinal curvature and scapulothoracic kinematics differed during propulsion when MWC seat dump angles were set at 0° and 14°. Although the different seat angles affect motion approaches, they do not appear to directly influence the risk of subacromial impingement because no differences were observed in the glenohumeral joint.

Practical Implications

Seating Adjustments

Clinicians can consider how seat dump angle affects spinal posture and scapular movement when prescribing wheelchair setups.

Targeted Interventions

Rehabilitation programs might need to address scapular stability and spinal alignment differently based on the level of spinal cord injury.

Further Research

Future studies should investigate the long-term effects of seat dump angle on shoulder health and function in wheelchair users.

Study Limitations

1
Our study captured propulsion over a limited period shortly after implementing the seating condition. Therefore, these results may not reflect long-term effects of these seating changes.
2
other body segments (e.g., pelvis, forearm, and hand) were not measured because of technical constraints. We are unable to conclude how these segments may have adapted or interacted with the spine and shoulder complex in response to the seating conditions.
3
although temporal variables could have been influenced by this seat angle change, they were not measured in this cohort.

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