Manual wheelchair users with spinal cord injury (SCI) are frequently diagnosed with subacromial impingement.
To determine whether the pattern of muscle imbalance and impaired scapular stabilization in able-bodied (AB) adults with impingement is different from that in manual wheelchair users with SCI and impingement.
The following measurements were collected from 22 adults with subacromial impingement (11 SCI, 11 AB): ratio of normalized muscle electrical activity of upper and lower trapezius (UT:LT) during arm abduction; force during abduction, adduction, internal rotation, external rotation, and push and pull; ratios of force for abduction to adduction (AB:ADD), internal to external rotation (IR:ER), and push to pull (PUSH:PULL).
Shoulders with impingement had significantly higher UT:LT activation (1.46 ± 0.52) than shoulders without impingement (0.93 ± 0.45) (P = .006), regardless of wheelchair user status. Significant differences between AB participants and those with SCI were observed for ABD:ADD (P = .005), PUSH:PULL (P = .012), and pull strength (P = .043). Participants with SCI had a significantly greater ABD:ADD (1.37 ± 0.36) than AB participants (1.04 ± 0.22) (P = .002) and a significantly greater PUSH:PULL (1.53 ± 0.36) than AB participants (1.26 ± 0.18) (P = .005) because of decreased strength in adduction (P = .021) and pull (P = .013).
Strategies targeting the posterior shoulder girdle for AB adults are appropriate for manual wheelchair users with SCI and impingement and should focus on scapular retractors and arm adductors with emphasis on scapular depression and posterior tilting.
Acknowledgments
The contents of this publication were developed under a grant from the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant no. 90RE5009). NIDILRR is a Center within the Administration for Community Living (ACL), Department of Health and Human Services (HHS). The contents of this article do not necessarily represent the policy of NIDILRR, ACL, HHS, and you should not assume endorsement by the Federal Government. Additional funding was provided by the UAB Department of Physical Medicine and Rehabilitation.
The authors declare no conflict of interest. The authors certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during the course of this research.
The authors thank all of the study participants.
