Date of Award

December 2021

Degree Type

Thesis

Degree Name

Master of Science

Department

Occupational Therapy

First Advisor

Brooke Slavens

Committee Members

Kris Barnekow, Joyce Engel

Keywords

axle position, biomechanics, pediatrics, shoulder, spinal cord injury, wheelchair

Abstract

Manual wheelchair (MWC) users with spinal cord injury (SCI) rely heavily on their upperextremities to complete daily occupations. Due to repetitive shoulder use during wheelchair mobility and propulsion, MWC users are at greater risk of shoulder pain and shoulder pathology, and thus decreased independence, and lower quality of life. The relative fit of the wheelchair and its parameters are critical and can further impact the user’s propulsion biomechanics. Parameters such as seat angle and axle position may put the user in detrimental shoulder positions for longer periods of time, impacting health outcomes even more. Although the effects of wheelchair setup on health outcomes have been explored in adult populations, little is known about the impact on pediatric MWC users, which is unfortunate because these children will live with the secondary medical conditions of an SCI longer than their adult counterparts. Limited research also exists on the wheelchair parameters currently being used by pediatric MWC users with SCI, and there are very few recommendations for wheelchair setup and fit specific to the pediatric population. This study aims to explore the seat and axle positions that are currently being used by pediatric MWC users with SCI, to identify the presence of shoulder pain and pathology in this population, and to determine if the relative fit of the pediatric wheelchair is related to pain, pathology, or independence scores in children with SCI. A total of 9 pediatric MWC users with SCI, ages 6-21, participated in this study. Three-dimension (3D) kinematics data were collected using 14-camera Vicon (Oxford Metric Group, Oxford, UK) Vantage and TS motion analysis systems. Shoulder pathologies were identified using diagnostic and quantitative ultrasound. Pain and independence outcomes were analyzed using the Wheelchair Users Shoulder Pain Index (WUSPI) and the Spinal Cord Independence Measure (SCIM). The mean seat angle used by the group was 5.16 degrees of elevation. Of the 9 participants, 7 used rearward axle positions in relation to their shoulders, while 2 used the adult recommended, forward axle position. Similarly, 4 of the participants followed the adult guideline to have an elbow flexion angle between 100-120 degrees, while 5 of the participants had their axles positioned non-optimally in the vertical direction according to adult guidelines. Shoulder pathologies were identified in 44% of the participants, and the average occupation ratio (percentage of the subacromial space occupied by the supraspinatus tendon) for the supraspinatus tendon was 69.62%. The average WUSPI score for the group was a 3.40 out of 150, and 4 of the 9 participants reported experiencing some level of shoulder pain on the assessment. The average SCIM score for all participants was a 67.13 out of 100, with age and time since injury strongly and significantly correlating with independence scores. After analyzing the data, a strong negative correlation between seat angle and occupation ratio was found. There was also a moderate correlation between the use of a non-optimal elbow angle and a higher WUSPI score. Finally, there was a strong positive correlation between seat angle and SCIM independence scores. Only weak correlations were found between horizontal axle positioning and the various outcomes, unlike the adult population. Results of this study will help to inform clinical decision-making when prescribing wheelchairs to children with SCI and when making wheelchair setup recommendations to pediatric MWC users and their families.

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