Comparison of shoulder joint motion and kinetics during fast and inclined reverse and conventional manual wheelchair propulsion in persons with paraplegia
1Lighthall Haubert L, 1Requejo P, 1Mulroy S, 1Maneekobkunwong S, 1Rodriguez D, 2Gronely J
1Rancho Los Amigos National Rehabilitation Center, Pathokinesiology Laboratory, Downey, California, United states; 2Rancho Los Amigos National Rehabilitation Center, Downey, California, United states
Objective: Rotator cuff pathology is the most common diagnosis for individuals with shoulder pain after spinal cord injury (SCI). Pain is attributed to a shift in weight bearing demands of functional mobility to the arms and negatively impacts independence and quality of life1, 2. Locomotion with a standard manual wheelchair (WC) imposes repetitive superior and posterior shoulder joint forces that increase with fast and inclined propulsion. If unopposed owing to fatigue or weakness3 these forces can result in impingement of subacromial structures. RoWheels® (RW), alternative geared rear wheels that produce forward WC movement with backward rim pulling, have the potential to reverse these shoulder joint forces and utilize the larger posterior shoulder and scapular muscles vs. traditional push-phase muscles.
Design/Methods: Ten males with paraplegia from SCI (AIS A, B) volunteered. Participants pushed traditional manual WCs and were free of shoulder pain (WC User’s Shoulder Pain Index (WUSPI) < 12) and pathology. A Qualisys motion capture system recorded 3D trunk and right upper extremity and wheel motion. Standard instrumented rear wheels (Smartwheels (SW)) captured right rim forces. Data were collected during six conditions of ergometer propulsion: self-selected fast and inclined reverse (pulling back on the rim) propulsion with RW, and matched-speed reverse and forward SW propulsion (rSW and fSW).
Results: Matched velocities were similar between RW, rSW and fSW during fast (RW=98.5 ± 19.6; rSW=102.6 ± 24.8; fSW=102.5 ± 18.5 meters/minute (m/min), respectively) and inclined propulsion (RW=39.1 ± 10.2; rSW=40.7 ± 9.0; fSW=41.3 ± 11.8 m/min, respectively). Shoulder extension at backward hand position was significantly less in fast and inclined RW and rSW (fast: 26 ± 7 and 17 ± 22 degrees (deg), respectively; and inclined: 25 ± 8 and 28 ± 11 deg, respectively) vs. fSW (fast: 42 ± 10 deg; inclined: 39 ± 12 deg.), p<0.05. Shoulder abduction (Abd) tended to be reduced at backward hand position in inclined RW (29 ± 4 deg) vs. fSW (34 ± 4 deg) and rSW (34 ± 6 deg), 0.05>p>0.10, but was significantly greater at forward hand position in fast RW (27 ± 5 deg) and rSW (28 ± 6 deg) vs. fSW (23 ± 5 deg), p<0.05. Posterior shoulder force was significantly decreased in fast and inclined rSW (27.0 ± 25.2 and 19.5 ± 12.4 Newtons (N)) vs. fSW (65.1 ± 25.1 and 85.8 ± 20.3 N). During inclined propulsion, superior shoulder force was significantly reduced in rSW vs. fSW (0.2 ± 29.2 vs. 48.4 ± 32.1 N) while anterior and inferior shoulder forces were increased (100.2 ± 30.9 vs. 37.5 ± 21.0 N and 125.8 ± 45.0 vs. 50.0 ± 6.7 N), p<0.05.
Conclusion: The significant reduction in the posterior (fast/inclined) and superior (inclined) shoulder forces during reverse propulsion in these high-demand conditions may substantially protect the subacromial structures from impingement to prevent injury/pain and preserve mobility, independence, and participation for individuals with paraplegia. Shoulder muscle activity during these conditions needs to be analyzed.
Support: RoWheels® Grant.
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