Shoulder Structural Changes in Manual Wheelchair Users with Spinal Cord Injury: Cross-Sectional Ultrasound Study of Supraspinatus Tendon Thickness and Acromiohumeral Distance.

Abstract

To investigate supraspinatus tendon thickness (SST), acromiohumeral distance (AHD), and occupation ratio (OR) in manual wheelchair (MWC) users with spinal cord injury (SCI), comparing symptomatic and asymptomatic shoulders versus able-bodied controls at rest, 60° abduction, and during weight-relief raises (WRR). Cross-sectional study. University rehabilitation center. The study included 34 MWC users with SCI (mean age 42.8±14.9 years; 67.6% male; BMI 25.8±4.37 kg/m²; 67.6% with T7-T12 level injuries; 60.79±53.46 months post-injury) and 29 able-bodied controls matched for age, sex, and BMI. Not applicable. Sonographic measurements of SST and AHD were performed in three positions, and OR was calculated by dividing SST by AHD. Clinical outcomes were assessed using the Shoulder Pain and Disability Index (SPADI) and Wheelchair User's Shoulder Pain Index (WUSPI). No significant between-group differences were found in AHD. SST was significantly greater in both symptomatic (ΔMean=+1.57 mm, 95%CI:0.92-2.22 mm, p<.001) and asymptomatic (ΔMean=+1.40 mm, 95%CI:0.75-2.04 mm, p<.001). Positional changes significantly influenced SST, with lower thickness at 60° abduction compared to WRR in symptomatic (ΔMean=-0.66 mm, p=.003) and asymptomatic (ΔMean=-0.57 mm, p=.015) groups, but not in controls. MWC users compared to able-bodied controls, and this was accompanied by a higher OR. Regression analysis showed that higher OR in the WRR position, greater SPADI scores, and longer MWC use significantly predicted WUSPI-assessed shoulder pain, with each 10% increase in OR linked to an average 3.41-point rise in WUSPI scores. OR may be more responsive to posture changes than AHD, suggesting that dynamic ultrasonographic assessment could serve as a practical tool to support clinical evaluations and inform targeted rehabilitation strategies for MWC users.