The relationship of shoulder pain intensity to quality of life, physical activity, and community participation in persons with paraplegia.

BACKGROUND/OBJECTIVE: For persons with spinal cord injury (SCI), severe bodily pain is related to a lower quality of life. However, the effect of pain from a specific body region on quality of life has yet to be determined. The shoulder joint is a common site of pain among persons with SCI. Therefore, our purpose was to identify the relationship of self-reported shoulder pain with quality of life, physical activity, and community activities in persons with paraplegia resulting from SCI. METHODS: Eighty participants with shoulder pain who propel a manual wheelchair (mean age: 44.7 years; mean duration of injury: 20 years; injury level T1-L2) completed the following questionnaires: Wheelchair User's Shoulder Pain Index, Subjective Quality of Life Scale, Physical Activity Scale for Individuals with Physical Disabilities, and Community Activities Checklist. Correlations between shoulder pain scores and quality of life, physical activity, and community activities were determined using Spearman's rho test. RESULTS: Shoulder pain intensity was inversely related to subjective quality of life (r(s) =-0.35; P= 0.002) and physical activity (r(s) = -0.42; P < 0.001). Shoulder pain intensity was not related to involvement in community activities (r(s) = -0.07; P = 0.526). CONCLUSIONS: Persons with SCI who reported lower subjective quality of life and physical activity scores experienced significantly higher levels of shoulder pain. However, shoulder pain intensity did not relate to involvement in general community activities. Attention to and interventions for shoulder pain in persons with SCI may improve their overall quality of life and physical activity.

A comparison of shoulder joint forces during ambulation with crutches versus a walker in persons with incomplete spinal cord injury.

OBJECTIVE: To compare 3-dimensional (3D) shoulder joint reaction forces and stride characteristics during bilateral forearm crutches and front-wheeled walker ambulation in persons with incomplete spinal cord injury (SCI). DESIGN: Cross-sectional cohort study. SETTING: Biomechanics laboratory. PARTICIPANTS: Fourteen adult volunteers with incomplete SCI recruited from outpatient rehabilitation hospital services. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Peak force, rate of loading, and force-time integral were compared for each component of the net 3D shoulder joint reaction force during ambulation with crutches and a walker. Stride characteristics were also compared between assistive device conditions. RESULTS: The largest weight-bearing force was superiorly directed, followed by the posterior force. The superior joint force demonstrated a significantly higher peak and rate of loading during crutch walking (48.9N and 311.6N/s, respectively, vs 45.3N and 199.8N/s, respectively). The largest non-weight-bearing force was inferiorly directed with a significantly greater peak occurring during crutch ambulation (43.2N vs 23.6N during walker gait). Walking velocity and cadence were similar; however, stride length was significantly greater during crutch walking (62% vs 58% of normal). CONCLUSIONS: Shoulder joint forces during assisted ambulation were large. Crutch use increased the superior force but did not increase walking velocity.

Effect of fore-aft seat position on shoulder demands during wheelchair propulsion: part 1. A kinetic analysis.

BACKGROUND/OBJECTIVE: The highly repetitive and weight-bearing nature of wheelchair (WC) propulsion has been associated with shoulder pain among persons with spinal cord injury (SCI). Manipulation of WC seat position is believed to reduce the overall demand of WC propulsion. The objective of this investigation was to document the effect of fore-aft seat position on shoulder joint kinetics. METHODS: Thirteen men with complete motor paraplegia propelled a test WC in 2 fore-aft seat positions during free, fast, and graded conditions. The seat-anterior position aligned the glenohumeral joint with the wheel axle and the seat-posterior position moved the glenohumeral joint 8 cm posteriorly. The right wheel of the test chair was instrumented to measure forces applied to the pushrim. An inverse dynamics algorithm was applied to calculate shoulder joint forces, external moments, and powers. RESULTS: For all test conditions, the superior component of the shoulder joint resultant force was significantly lower in the seat-posterior position. During graded propulsion, the posterior component of the shoulder joint force was significantly higher with the seat posterior. Peak shoulder joint moments and power were similar during free and fast propulsion. During graded propulsion, the seat-posterior position displayed increased internal rotation moment, decreased sagittal plane power absorption, and increased transverse plane power generation. CONCLUSIONS: This investigation provides objective support that a posterior seat position reduces the superior component of the shoulder joint resultant force. Consequently, this intervention potentially diminishes the risk for impingement of subacromial structures.

Effect of fore-aft seat position on shoulder demands during wheelchair propulsion: part 2. An electromyographic analysis.

BACKGROUND/OBJECTIVES: Shoulder pain is common in persons with complete spinal cord injury. Adjustment of the wheelchair-user interface has been thought to reduce shoulder demands. The purpose of this study was to quantify the effect of seat fore-aft position on shoulder muscle activity during wheelchair propulsion. METHODS: Shoulder electromyography (EMG) was recorded while 13 men with paraplegia propelled a wheelchair in the following 2 seat positions: (a) shoulder joint center aligned with the wheel axle (anterior) and (b) shoulder joint center 8 cm posterior to the wheel axle (posterior) in 3 test conditions (free, fast, and graded). Duration of EMG activity and median and peak intensities were compared. RESULTS: During free propulsion, the median EMG intensity of all muscles was similar between anterior and posterior seat positions. The major propulsive muscles (pectoralis major and anterior deltoid) demonstrated significant reductions in their median and peak intensities in the posterior seat position. Pectoralis major median intensity was significantly reduced in the posterior position during fast (52% vs 66% maximal muscle test [MMT]) and graded (41 % vs 49% MMT) conditions, and peak intensity was significantly reduced in the free condition (29% vs 52% MMT) and the fast condition (103% vs 150% MMT). Anterior deltoid intensity was significantly reduced in the posterior position during fast propulsion only (26% vs 31% MMT). For all muscles, EMG duration was similar between positions in all test conditions. CONCLUSIONS: Reduction in the intensity of the primary push phase muscles (pectoralis major and anterior deltoid) during high-demand activities of fast and graded propulsion may reduce the potential for shoulder muscle fatigue and injuries.