EVALUATION OF SHOULDER JOINT KINEMATICS AND STROKE CYCLE CHARACTRESTICS DURING GEARED AND STANDARD MANAUL WHEELCHAIR MOBILITY

Omid Jahanian, Alyssa J. Schnorenberg, Lianna Hawi and Brooke A. Slavens

Department of Occupational Science & Technology, University of Wisconsin-Milwaukee, Milwaukee, WI

ABSTRACT

Geared manual wheelchairs may be a promising alternative for standard manual wheelchairs that reduce the biomechanical demands of the upper extremity joints, while maximizing function and participation. To investigate the effects of geared manual wheelchair mobility during demanding tasks such as ramp ascending, six able-bodied subjects were evaluated in this study. Subjects were asked to perform level and upslope stroking tasks using both standard and geared manual wheelchairs. Stroke cycle characteristics and shoulder joint kinematics were investigated. The results indicated that using geared manual wheelchair wheels did not alter the glenohumeral joint kinematics, but caused significant changes in stroke cycle characteristics particularly during demanding tasks such as ramp ascent. These results could have clinical implications for determining the types of mobility tasks and populations of users for which geared manual wheelchair are beneficial. The results from this work will also help improve the current geared wheel design and develop new multi-geared wheels for manual wheelchairs.

BACKGROUND

Manual wheelchairs often lead to reduced independent function (Van der Woude, 2005) and an increase in shoulder pain and injuries (Alm, 2008).  Geared manual wheelchairs may be a promising alternative that reduce the biomechanical demands of the shoulder needed for demanding tasks such as propulsion on ramps and carpeted floors, while maximizing function and participation.  Previous work by our group showed that glenohumeral (GH) joint kinematics in all three planes of motion were not significantly different between geared wheels and standard wheels during level propulsion on tiled and carpeted floors, but stroke frequency increased significantly during geared mobility (Jahanian, 2015). Electromyography (EMG) of shoulder muscles during level stroking and upslope stroking, has shown a significant decrease in shoulder muscle activity during geared manual wheelchair mobility (Howarth, 2010). Shoulder pain reduction among manual wheelchair users was also reported as one of the potential advantages of geared manual wheelchair mobility (Finley, 2007). However, there is still limited scientific evidence supporting the benefits of geared manual wheelchair mobility.  The goal of our work is to elucidate the biomechanical mechanisms affected by geared manual wheelchairs.

PURPOSE

The purpose of this study was to compare the upper extremity joint kinematics and stroke cycle characteristics during level stroking and upslope stroking when using geared and standard manual wheelchairs.  Using a repeated measure design, we aimed to address the following research questions:

  1. Does wheel type cause significant changes in stroke cycle characteristics and shoulder joint kinematics?
  2. Does slope cause significant changes in stroke cycle characteristics and shoulder joint kinematics?

METHOD

Subjects

Six individuals, three females and three males, ages 20-23 were recruited for this study. All participants were able-bodied and had no prior wheelchair experience.  This study was approved by the University of Wisconsin-Milwaukee institutional review board (IRB). Prior to data collection, each participant read and signed an informed consent document. An acclimation period (15-30 min) was provided for the participants to become familiarized with wheelchair propulsion techniques.

Data Collection

Picture of the upper extremity model used for kinematic data collection and processing. On left side there is the anterior view of the upper extremity model and on right side the posterior view of the model. In this picture the marker set is represented by filled circles on suprasternal notch, xiphoid process, spinous process at C7, Acromioclavicular joint , inferior angle of scapula, trigonum spine, scapular spine, acromial angle, coracoid process, humerus, olecranon, radial and ulnar styloids, third and fifth metacarpals. In this picture Joint centers are represented by the open circles: wrist, elbow, glenohumral, acromioclavicular, sternoclavicular joint centers and the thorax center. Arrows indicate global coordinate system & segmental coordinate systems.
Figure 1: 3D Bilateral UE biomechanical model (Schnorenberg, 2014)
Subjects were instrumented with 27 reflective markers on the hands, forearms, upper arms, scapulae, clavicles, and thorax (Schnorenberg, 2014), (Figure 1). Participants were asked to propel both standard and geared manual wheelchairs along a 20 ft tiled level-floor and on an 8 ft ADA wheelchair ramp (4.8 degrees slope) at a self-selected normal speed and propulsion pattern for five trials. Each ramp ascent trial began on a level surface with the participant positioned approximately 3 feet from the ramp base. A Breezy MW (Sunrise Medical LLC.) was used with both its standard wheels and Easy Push (IntelliWheels, Inc.) geared wheels (gear ratio of 1:1.6). Motion analysis data was collected using a 15 camera, three-dimensional (3-D) Vicon T-series motion capture system (120 Hz).

Data Processing

To identify the push and recovery phases of each propulsion stroke, sagittal kinematics of the marker placed on the third metacarpal was used. The three critical instants were the first initial hand contact (HC1), hand release (HR) and the second initial hand contact (HC2). Push phase was defined as HC1 to HR and a complete stroke was from HC1 to HC2. Temporal parameters (stroke time, push time expressed as percentage of stroke time and stroke frequency) were determined using the frame numbers and intervals between consecutive frames (1/120 s). Stroke distance was computed as the distance between the location of the wheel center at HC1 and at HC2. Stroke speed was calculated by dividing the stroke distance by the stroke time. Normalized stroke frequency was obtained by dividing the stroke frequency by the stroke distance. For the ramp trials, the stroke when the wheelchair castors passed the midpoint of the ramp, and for the level stroking trials, the forth stroke were selected from each trial for analysis. The method used for determination of stroke cycle characteristics was constant with the approach defined by Chow and colleagues (Chow, 2009). 

A custom inverse dynamics model (Schnorenberg, 2014) was used to calculate the 3-D upper extremity (UE) joint dynamics. The results for GH joint (humerus relative to thorax) in all three kinematic planes (sagittal, coronal and transverse) were used for analysis.

Data Analysis

Mean and standard deviation of stroke cycle characteristics and GH joint kinematics were computed for each wheel type (standard / geared) and slope (level-floor / ramp). A two-way analysis of variance (2 wheel x 2 slopes) with repeated measures was used for statistical analysis. If there was no significant interaction between the factors, main effects were investigated using Bonferroni adjusted t-test. When there was significant interaction between factors, simple effects of wheel factor within each each level of slope were examined. All statistical analyses were completed with IBM SPSS software using general linear model repeated measure (significance level = 0.05).

RESULTS AND DISCUSSION

Stroke Cycle Characteristics

This picture shows three separate graphs comparing the average glenohumeral joint trajectories between geared and standard manual wheelchairs in the sagittal, coronal and transverse planes when propelling up a ramp. Each graph displays one complete stroke cycle. For all three graphs, a solid red line is used to show the glenohumeral joint trajectory when using the standard wheel and a solid blue line is used to show the glenohumeral joint trajectory when using the geared wheel. The standard deviation for each wheel is also shown; a red dotted line corresponding to the glenohumeral joint trajectory plus/minus one standard deviation for the standard wheel and a blue dotted line corresponding to the glenohumeral joint trajectory plus/minus one standard deviation for the geared wheel. The first graph displays flexion and extension of the glenohumeral joint in the sagittal plane up a ramp. In this graph, both solid lines are bell shaped. The glenohumeral joint using the geared wheel is in flexion until it peaks at 59% of the stroke cycle at 45 degrees and the glenohumeral joint using the standard wheel is in flexion until it peaks at 62% of the stroke cycle at 42 degrees. The peaks correspond to the end of the push phase. Throughout this graph, the trajectories between the two wheels are similar. The second graph displays adduction and abduction of the glenohumeral joint in the coronal plane up a ramp. In this graph, both solid lines resemble a sine wave. The glenohumeral joint trajectory using the geared wheel peaks at 59% of the stroke cycle at 25 degrees while the glenohumeral joint trajectory using the standard wheel peaks at 61% of the stroke cycle at 26 degrees. Again, the peaks correspond to the end of the push phase and the trajectories between the two wheels are similar. The third graph displays internal rotation and external rotation of the glenohumeral joint in the coronal plane up a ramp. In this graph, both solid lines resemble a bell shape. The glenohumeral joint trajectory using the geared wheel peaks at 54% of the stroke cycle at 27 degrees while the glenohumeral joint trajectory using the standard wheel peaks at 58% of the stroke cycle at 31 degrees. The range of motion of the standard wheel joint is greater than that of the geared wheel joint. The peaks correspond to the end of the push phase. Throughout this graph, the trajectories between the two wheels are similar.
Figure 2: GH joint trajectories in sagittal, coronal and transverse planes. Group mean profile (solid line) and +/- one standard deviation (dotted line) of six able-bodied subjects (dominant side) for geared and standard manual wheelchairs propulsion on ramp
Mean and standard deviation for stroke cycle parameters (speed, stroke time, stroke distance, stroke frequency and normalized stroke frequency) are reported (Table 1). Repeated measure factorial analysis of stroke cycle characteristics (6 able-bodied subjects) showed that there is no significant interaction between factors (wheel type and slope) for speed, stroke time, push time and stroke distance. The results for main effects determined that the mean value for speed decreased significantly (p = 0.003) during geared mobility (0.66 m/s) in comparison to standard wheelchair mobility (0.86 m/s) regardless of level of slope. Push time and stroke distance also decreased significantly (p = 0.002) during geared manual wheelchair stroking (50.43 %, 0.7 m) in comparison to standard manual wheelchair (56.03 %, 0.9 m). Wheel type did not cause any significant changes on stroke time.

This picture shows three separate graphs comparing the average glenohumeral joint trajectories between geared and standard manual wheelchairs in the sagittal, coronal and transverse planes when propelling on tiled level floor. Each graph displays one complete stroke cycle. For all three graphs, a solid red line is used to show the glenohumeral joint trajectory when using the standard wheel and a solid blue line is used to show the glenohumeral joint trajectory when using the geared wheel. The standard deviation for each wheel is also shown; a red dotted line corresponding to the glenohumeral joint trajectory plus/minus one standard deviation for the standard wheel and a blue dotted line corresponding to the glenohumeral joint trajectory plus/minus one standard deviation for the geared wheel. The first graph displays flexion and extension of the glenohumeral joint in the sagittal plane on tiled level floor. In this graph, both solid lines are bell shaped. The glenohumeral joint using the geared wheel is in flexion until it peaks at 43% of the stroke cycle at 42 degrees and the glenohumeral joint using the standard wheel is in flexion until it peaks at 50% of the stroke cycle at 42 degrees. The peaks correspond to the end of the push phase. Throughout this graph, the trajectories between the two wheels are similar. The second graph displays adduction and abduction of the glenohumeral joint in the coronal plane on tiled level floor. In this graph, both solid lines resemble a sine wave. The glenohumeral joint trajectory using the geared wheel peaks at 42% of the stroke cycle at 28 degrees while the glenohumeral joint trajectory using the standard wheel peaks at 58% of the stroke cycle at 25 degrees. Again, the peaks correspond to the end of the push phase and the trajectories between the two wheels are similar. The third graph displays internal rotation and external rotation of the glenohumeral joint in the coronal plane on tiled level floor. In this graph, both solid lines resemble a bell shape. The glenohumeral joint trajectory using the geared wheel peaks at 40% of the stroke cycle at 25 degrees while the glenohumeral joint trajectory using the standard wheel peaks at 45% of the stroke cycle at 28 degrees. The range of motion of the standard wheel joint is greater than that of the geared wheel joint. The peaks correspond to the end of the push phase. Throughout this graph, the trajectories between the two wheels are similar.
Figure 3: GH joint trajectories in sagittal, coronal and transverse planes. Group mean profile (solid line) and +/- one standard deviation (dotted line) of six able-bodied subjects (dominant side) for geared and standard manual wheelchairs propulsion on tiled level-floor
The effect of wheel type on stroke frequency was not the same regardless of slope (p = 0.028), there was also significant interaction between wheel and slope factors (p = 0.013) for normalized stroke frequency. Therefore, simple effects were investigated for these independent variables (stroke frequency and normalized stroke frequency). The effect of wheel type on stroke frequency during level stroking and upslope stroking was not statistically significant. During level stroking, normalized stroke frequency was not statistically different between geared wheel and

standard wheel conditions, but during upslope stroking normalized stroke frequency increased significantly (49%, p = 0.05) during geared manual wheelchair mobility. The results for normalized stroke frequency indicated that for travelling the same distance a higher number of strokes is required while using geared manual wheelchairs.

GH Joint Kinematics

There was no significant interaction between the factors (wheel and slope), and GH joint kinematics of six subjects were not significantly different between geared wheels and standard wheels. GH joint angle mean ranges of motion in the sagittal, coronal and transverse plane are presented (Table 2). Figure 2-3 illustrate the kinematic trajectories of GH joint in three planes and for geared and standard manual wheelchair during upslope stroking and level stroking.

Study Limitations

Small sample size and testing able-bodied subjects instead of experienced manual wheelchair users were the main limitations of this study. Further investigation is underway with a larger population of able-bodied persons and manual wheelchair users with spinal cord injury.

CONCLUSION

Previous studies on geared manual wheelchair mobility had reported potential benefits in terms of muscle activity and pain reduction. The results of this study showed that using the geared manual wheelchair did not alter GH joint kinematics, but it caused significant changes in stroke cycle characteristics particularly during demanding tasks such as ramp ascent. The significant increase in number of required strokes for travelling a specific distance can be the main drawback of geared manual wheelchairs. The results from this study have clinical implications for development of manual wheelchair prescription guidelines. These results will help us determine the types of mobility tasks and populations of users for which geared manual wheelchairs are beneficial. Ultimately, this work will lead to new multi-geared wheel designs for manual wheelchairs.

REFERENCES

Alm, M., Saraste, H., & Norrbrink, C. (2008). Shoulder pain in persons with thoracic spinal cord injury: prevalence and characteristics. Journal of rehabilitation medicine, 40(4), 277-283.

Chow, J. W., Millikan, T. A., Carlton, L. G., Chae, W. S., Lim, Y. T., & Morse, M. I. (2009). Kinematic and electromyographic analysis of wheelchair propulsion on ramps of different slopes for young men with paraplegia. Archives of physical medicine and rehabilitation, 90(2), 271-278.

Finley, M. A., & Rodgers, M. M. (2007). Effect of 2-speed geared manual wheelchair propulsion on shoulder pain and function. Archives of physical medicine and rehabilitation, 88(12), 1622-1627.

Howarth, S. J., Pronovost, L. M., Polgar, J. M., Dickerson, C. R., & Callaghan, J. P. (2010). Use of a geared wheelchair wheel to reduce propulsive muscular demand during ramp ascent: Analysis of muscle activation and kinematics. Clinical Biomechanics, 25(1), 21-28.

Jahanian, O., Schnorenberg, A. J., Hawi, L., & Slavens, B. A. Upper extremity joint dynamics and electromyography (EMG) during standard and geared manual wheelchair propulsion, Proceeding of the 39th Annual Meeting of American Society of Biomechanics, Columbus, OH.

Schnorenberg, A. J., Slavens, B. A., Wang, M., Vogel, L. C., Smith, P. A., & Harris, G. F. (2014). Biomechanical model for evaluation of pediatric upper extremity joint dynamics during wheelchair mobility. Journal of biomechanics, 47(1), 269-276.

van der Woude, L. H., & de Groot, S. (2005). Wheelchair propulsion: a straining form of ambulation. Indian Journal of Medical Research, 121(6), 719.

ACKNOWLEDGEMENT

The content of this work were developed under a student research grant from UW-Milwaukee College of Health Sciences (CHS) and a SBIR grant awarded by the National Institutes of Health, grant number 2R44HD071653-02.  However, the contents of this work do not necessarily represent the policy of the UWM CHS and the NIH.