Shoulder pain in persons with tetraplegia and the association with force application during manual wheelchair propulsion
Authors: Arnet Ursina , Bossuyt Franziska , Beirens Benjamin , De Vries Wiebe 
Published: February 2023

Introduction
Shoulder pain is highly prevalent in persons with spinal cord injury (Liampas et al., 2021) and restricts daily mobility and thus participation and quality of life. Shoulder loading activities, such as manual wheelchair propulsion or transfers, are seen as risk factors for shoulder pain. To minimize the risk for shoulder pain, clinical guidelines instruct persons with spinal cord injury to “use long, smooth strokes that limit high impacts on the pushrim”. Findings supporting this recommendation have been found for persons with paraplegia (Beirens et al., 2021). However, dependent on their lesion level, persons with tetraplegia do not have, full triceps function and are not able to grasp the hand rim properly, which will alter force application and may further impact shoulder pain. The aim of this study was to investigate the association between wheelchair propulsion biomechanics, including force application and spatio-temporal characteristics, and shoulder pain in persons with tetraplegia.
Methods
Sixteen community-dwelling, wheelchair dependent participants with tetraplegia (C7-C5, age 49.1 ±2.9 years, 23.4 ±2.4 years since injury, 94% male) were measured during wheelchair propulsion on a treadmill at two speed / power output conditions: 0.56 ms-1/10W and 0.83 ms-1/15W. A Smartwheel was fitted to the personal wheelchair to measure force application. The applied forces, their effectiveness (fraction of effective force) and smoothness (rate of rise of force, jerk), as well as push frequency, push angle and timing of the push cycles were analyzed. Based on the Wheelchair User Shoulder Pain Index (0-150), participants were stratified in groups with low (≤ 7), moderate (8-35) and high (≥ 36) shoulder pain. A mixed-effect multilevel analysis was used to identify the association between the dependent variables (propulsion biomechanics) and group of shoulder pain when controlling for sex, age, time since injury, lesion level, body weight and height.
Results and Discussion
The analysis showed that persons with high shoulder pain applied the force over a longer push angle (85.6°) and had a shorter recovery time (0.4s) and applied the force more effective (FEF = 40.7%) than persons with low pain (push angle = 81.2°, recovery time = 0.5s, FEF = 35.2%). In addition, persons with high shoulder pain applied less medial directed force (6.4 N) compared to persons with moderate pain (14.9 N). The results of this cross-sectional study on wheelchair propulsion in persons with tetraplegia are in contradiction to previously reported results in person with paraplegia (Beirens et al., 2021). Interestingly, tetraplegic persons with high shoulder pain are following clinical recommendation on how to propel the wheelchair optimally. These results support the importance of differentiating between lesions levels when further investigating force application as a risk factor for shoulder pain. In addition, the results ask for a close examination and possible adaptation of the clinical guidelines for persons with tetraplegia.
References
Beirens, B. J. H., Bossuyt, F. M., Arnet, U., van der Woude, L. H. V., & de Vries, W. H. K. (2021). Shoulder pain is associated with rate of rise and jerk of the applied forces during wheelchair propulsion in individuals with paraplegic spinal cord injury. Archives of Physical Medicine and Rehabilitation, 102(5), 856-864. https://doi.org/10.1016/j.apmr.2020.10.114
Liampas, A., Neophytou, P., Sokratous, M., Varrassi, G., Ioannou, C., Hadjigeorgiou, G. M., & Zis, P. (2021). Musculoskeletal pain due to wheelchair use: A systematic review and meta-analysis. Pain and Therapy, 10, 973-984. https://doi.org/10.1007/s40122-021-00294-5