Elbow kinematics during overground manual wheelchair propulsion in individuals with tetraplegia

Purpose.?The purpose of this study was to describe horizontal and vertical translation of the elbow and elbow angle in two planes and three speeds during manual wheelchair overground propulsion in individuals with tetraplegia.

Methods.?Seven individuals with tetraplegia who used manual wheelchairs wheeled overground at three different speeds were recruited for the study. Video motion capture methods quantified their movements. Video data were tracked and used to calculate variables describing three-dimensional elbow translation and angular orientation. Repeated measures ANOVA were used to determine effects of speed on elbow translation and elbow angle. Paired t-tests were used to evaluate left to right differences.

Results.?Right elbow anterior-posterior translation was found to be significantly different during slow and fast and slow and normal speeds. Vertical and medial-lateral translation of the right elbow was significantly different between slow and fast speeds. No significant effects for speed during left elbow movement or side-to-side movement were found. No significant effects were found for elbow angle across speeds or from side-to-side. Three patterns of elbow movement emerged for anterior-posterior and medial-lateral translation and for elbow angle.

Conclusions.?Results indicated that elbow translation was related to propulsion speed. Work involving this population is needed for further understanding of upper extremity kinematic patterns.     

Oxygen uptake during peak graded exercise and single-stage fatigue tests of wheelchair propulsion in manual wheelchair users and the able-bodied.

OBJECTIVE: To determine if a single-stage, submaximal fatigue test on a wheelchair ergometer would result in higher than expected energy expenditure. DESIGN: An experimental survey design contrasting physiologic responses during peak graded exercise tests and fatigue tests. SETTING: A rehabilitation science laboratory that included a prototypical wheelchair ergometer, open-circuit spirometry system, and heart rate monitor. PARTICIPANTS: Nine able-bodied non-wheelchair users (the NWC group: 6 men and 3 women, mean +/- SD age 30 +/- 7yrs) and 15 manual wheelchair users (the WC group: 12 men and 3 women, age 40 +/- 9yrs, time in wheelchair 16 +/- 9yrs). No subject had any disease, medication regimen, or upper body neurologic, orthopedic, or other condition that would limit wheelchair exercise. MAIN OUTCOME MEASURES: Peak oxygen uptake (VO2) for graded exercise testing and during fatigue testing, using a power output corresponding to 75% peak aerobic capacity on graded exercise test. RESULTS: In the WC group, VO2 at 6 minutes of fatigue testing was not significantly different from peak VO2. In the NWC group, VO2 was similar to the expected level throughout fatigue testing. CONCLUSION: Energy expenditure was higher than expected in the WC group but not in the NWC group. Fatigue testing may provide a useful evaluation of cardiorespiratory status in manual wheelchair users.     

Scapular kinematics in professional wheelchair tennis players

BackgroundParticipating in wheelchair tennis increases the demands placed on the shoulder and could increase the risk of developing shoulder pain and injury that might be associated with differences in scapular kinematics. The aim of the study was to examine the presence of shoulder pain and scapular kinematics in professional wheelchair tennis players.MethodScapular kinematics were obtained in 11 professional wheelchair tennis players, 16 people with shoulder impingement and 16 people without shoulder impingement during humeral elevation and lowering. Clinical examination of the wheelchair tennis players was undertaken using the Wheelchair Users Shoulder Disability Index (WUSPI) and clinical signs of shoulder impingement.FindingsThe WUSPI questionnaire (mean = 28 SD 13.8) demonstrated wheelchair tennis participants experienced little shoulder pain and clinical examination revealed negative impingement tests. Wheelchair tennis players had greater scapular posterior tilt during humeral elevation (3.9° SE 1.71; P = 0.048) and lowering (4.3° SE 1.8; P = 0.04) on the dominant compared to non-dominant side. The dominant scapulae of wheelchair tennis players were significantly (P = 0.014) more upwardly rotated (21° SD 6.7) than the scapulae of people with shoulder impingement (14.1° SD 7.0) during scapular plane humeral elevation.InterpretationThis first study of scapular kinematics in professional wheelchair tennis athletes demonstrated bilateral asymmetries and differences to able-bodied participants with shoulder impingement. Understanding the role of sport participation on shoulder function in wheelchair users would assist in the development of preventative and treatment exercise programmes for wheelchair users at risk of shoulder injury and pain.     

Upper limb joint dynamics during manual wheelchair propulsion

Background

Inverse dynamic methods have been widely used to estimate joint loads during manual wheelchair propulsion. However, the interpretation of 3D net joint moments and powers is not always straightforward. It has been suggested to use joint coordinate systems (expression of joint moment on anatomical axes) and the 3D angle between joint moment and angular velocity vectors (propulsion, resistance or stabilization joint configuration) for a better understanding of joint dynamics.

Methods

Nine spinal cord injured subjects equipped with reflective markers propelled in a wheelchair with an instrumented wheel. Inverse dynamic results were interpreted using joint coordinate systems, 3D joint power and the 3D angle between the joint moment and joint angular velocity vectors at the three upper limb joints. The 3D angle was used to determine if the joints were predominantly driven (angle close to 0 or 180 degrees) or stabilized (angle close to 90°).

Findings

The wrist and elbow joints are mainly in a stabilization configuration (angle close to 90°) with a combination of extension and ulnar deviation moments and an adduction moment respectively. The shoulder is in a propulsion configuration, but close to stabilization (angle hardly below 60°) with a combination of flexion and internal rotation moments.

Interpretation

Stabilization configuration at the joints could partly explain the low mechanical efficiency of manual wheelchair propulsion and could give insight about injury risk at the wrist, elbow and shoulder joints.     

Scapula kinematics and associated impingement risk in manual wheelchair users during propulsion and a weight relief lift

Background

Shoulder impingement syndrome is a common upper extremity pathology in manual wheelchair users. Central to impingement is the orientation of the scapula and humerus as they determine the available subacromial space. The purpose of this study was to examine the scapulothoracic and glenohumeral internal/external rotation kinematics during the time of peak shoulder loading of propulsion and weight relief lift conditions to assess possible risk of impingement.

Methods

Scapula, humerus and trunk kinematics were measured for twelve manual wheelchair users over three conditions: level propulsion, ramp propulsion, and a weight relief lift. Scapulothoracic and glenohumeral kinematic variables were characterized for the full cycle of each condition as well as at the period of peak loading.

Findings

Common to all activities was an externally rotated glenohumeral joint and an anteriorly tilted and internally rotated scapula. At peak loading, glenohumeral internal/external rotation showed a significant difference between conditions, and post hoc analysis revealed that the weight relief lift displayed significantly less external rotation at peak loading when compared to level and ramp propulsion.

Interpretation

All activities placed the scapula in a potentially dangerous orientation for development of shoulder impingement. The weight relief lift, with a decrease in glenohumeral external rotation and large superior forces at the shoulder, potentially places the shoulder of the manual wheelchair user at the greatest risk for impingement soft tissue injury. Preventative strength training and activity modification may provide measures to slow progression of impingement development and associated pain in the manual wheelchair user.     

Comparing the shoulder impingement kinematics between circular and pumping strokes in manual wheelchair propulsion

Purpose.?The study aimed to investigate the glenohumeral kinematic difference between the circular and pumping strokes in manual wheelchair users.

Method.?This is a repeated measures design with randomised testing conditions. We recruited 10 manual wheelchair users and asked them to perform both the pumping and circular strokes on a stationary roller system. We used the Zebris motion analysis system to collect the 3-dimension glenohumeral motion data.

Results.?The pumping and the circular strokes were similar in the starting and ending positions in the sagittal plane. However, the pumping stroke started at a significantly larger abduction and internal rotation and ended with a significantly larger abduction and even larger internal rotation, it also traveled more ranges in all three planes and stayed longer in the combined positions of rotation/flexion and rotation/abduction as compared to the circular stroke.

Conclusions. The circular stroke appeared more advantageous than the pumping technique in the injury prevention prospect because the latter involved more flexion, abduction and internal rotation of the shoulder, which could add more impingement stresses to the joint. Clinicians may need to prescribe proper wheelchair propulsion techniques for their clients to avoid accumulating impingement stresses in the shoulder joints.     

Shoulder kinematics and kinetics during two speeds of wheelchair propulsion

The primary objective of this study was to examine the kinematics and kinetics of the shoulder during wheelchair propulsion at a slow and moderate speed. Twenty-seven individuals with paraplegia propelled their wheelchairs at speeds of 0.9 m/s and 1.8 m/s while a motion analysis system captured movements of their upper limbs and SMART(Wheel)s simultaneously recorded their pushrim kinetics. Intraclass R correlation and Cronbach's coefficient alpha statistics revealed that all shoulder parameters were stable and consistent between strokes and speeds. The shoulder exhibited a greater range of motion, and forces and moments at the shoulder were 1.2 to 2.0 times greater (p < 0.05) during the 1.8 m/s speed trial. Peak posterior forces occurred near the end of the propulsion phase, and at the same time, the shoulder was maximally flexed and minimally abducted (p > 0.1). Shoulder positioning and the associated peak shoulder loads during propulsion may be important indicators for identifying manual wheelchair users at risk for developing shoulder pain and injury.     

Pelvic movement and interface pressure distribution during manual wheelchair propulsion

OBJECTIVE: To investigate the movement of the ischial tuberosities and the redistribution of interface pressure during manual wheelchair propulsion. DESIGN: Measurement of ischial tuberosity positions and comparison with corresponding position of the zones of peak pressure by using independent samples t tests. Analysis of variance was used to compare peak and average pressures under static and dynamic conditions. SETTING: Human locomotion laboratory. PARTICIPANTS: Ten subjects with spinal cord injury (SCI) and 10 individuals with no disabilities. INTERVENTIONS: Manual wheelchair propulsion on a stationary wheelchair ergometer at the subject's maximum propulsion speed. MAIN OUTCOME MEASURES: Seat interface pressure and the 3-dimensional position of the pelvis were measured with a pressure mat and an optical motion analysis system. RESULTS: During wheelchair sprinting, the ischia were located at 19.2+/-11.7 mm behind the corresponding peak pressure locations. The anteroposterior rocking of the pelvis was 11.2 degrees and 5.2 degrees for the normal and SCI group, respectively. The average interface pressure over the ischial tuberosity area was lower under dynamic conditions. It was also observed in the SCI group that there was a concentration of high-pressure gradients around the peak pressure areas of the buttock during dynamic propulsion. CONCLUSION: Peak pressure locations did not concur exactly with the ischial tuberosities during propulsion. The movements of the ischial bone and the cyclic loading imposed on the tissue underneath the ischial tuberosities during dynamic conditions may have implications for the etiology of decubitus ulcers.     

Adaptations in physiology and propulsion techniques during the initial phase of learning manual wheelchair propulsion

OBJECTIVE: The purpose of this study was to analyze adaptations in gross mechanical efficiency and wheelchair propulsion technique in novice able-bodied subjects during the initial phase of learning hand-rim wheelchair propulsion. DESIGN: Nine able-bodied subjects performed three 4-min practice blocks on a wheelchair ergometer. The external power output and velocity of all blocks was, respectively, 0.25 W/kg and 1.11 m/sec. Gross mechanical efficiency, force application, timing, and intercycle variability were measured. RESULTS: No change in gross mechanical efficiency was found. However, a decrease in push frequency occurred, which was accompanied by an increase in work per cycle and a decrease in percentage push time. The increase in work per cycle was associated with a higher peak torque. No changes in intercycle variability were visible over time. CONCLUSIONS: The timing variables had already changed during the initial phase of learning manual wheelchair propulsion. However, for other variables, such as force production, gross mechanical efficiency, and intercycle variability, a longer practice period might be necessary to induce a change. The effective force direction seemed to be optimized from the start of the learning process onward.     

Variability of peak shoulder force during wheelchair propulsion in manual wheelchair users with and without shoulder pain

BackgroundManual wheelchair users report a high prevalence of shoulder pain. Growing evidence shows that variability in forces applied to biological tissue is related to musculoskeletal pain. The purpose of this study was to examine the variability of forces acting on the shoulder during wheelchair propulsion as a function of shoulder pain.MethodsTwenty-four manual wheelchair users (13 with pain, 11 without pain) participated in the investigation. Kinetic and kinematic data of wheelchair propulsion were recorded for 3 min maintaining a constant speed at three distinct propulsion speeds (fast speed of 1.1 m/s, a self-selected speed, and a slow speed of 0.7 m/s). Peak resultant shoulder forces in the push phase were calculated using inverse dynamics. Within individual variability was quantified as the coefficient of variation of cycle to cycle peak resultant forces.FindingsThere was no difference in mean peak shoulder resultant force between groups. The pain group had significantly smaller variability of peak resultant force than the no pain group (P < 0.01, η² = 0.18).InterpretationThe observations raise the possibility that propulsion variability could be a novel marker of upper limb pain in manual wheelchair users.     

Biomechanic evaluation of upper-extremity symmetry during manual wheelchair propulsion over varied terrain

Hurd WJ, Morrow MM, Kaufman KR, An K-N. Biomechanic evaluation of upper-extremity symmetry during manual wheelchair propulsion over varied terrain.

Objective

To evaluate upper-extremity symmetry during wheelchair propulsion across multiple terrain surfaces.

Design

Case series.

Setting

A biomechanics laboratory and the general community.

Participants

Manual wheelchair users (N=12).

Interventions

Not applicable.

Main Outcome Measures

Symmetry indexes for the propulsion moment, total force, tangential force, fractional effective force, time-to-peak propulsion moment, work, length of push cycle, and power during wheelchair propulsion over outdoor and indoor community conditions, and in laboratory conditions.

Results

Upper-extremity asymmetry was present within each condition. There were no differences in the magnitude of asymmetry when comparing laboratory with indoor community conditions. Outdoor community wheelchair propulsion asymmetry was significantly greater than asymmetry measured during laboratory conditions.

Conclusions

Investigators should be aware that manual wheelchair propulsion is an asymmetrical act, which may influence interpretation when data is collected from a single limb or averaged for both limbs. The greater asymmetry identified during outdoor versus laboratory conditions emphasizes the need to evaluate wheelchair biomechanics in the user's natural environment.     

Propulsion patterns and pushrim biomechanics in manual wheelchair propulsion

OBJECTIVES: To classify stroke patterns of manual wheelchair users and to determine if different patterns of propulsion lead to different biomechanics. DESIGN: Case series. SETTING: Biomechanics laboratory. PARTICIPANTS: Thirty-eight individuals with paraplegia who use manual wheelchairs for mobility. INTERVENTION: Subjects propelled their own wheelchair on a dynamometer at 2 different steady state speeds. Bilateral biomechanical data were obtained by using a force and moment sensing pushrim and a motion analysis system. MAIN OUTCOME MEASURES: The propulsive stroke of each participant for each speed and side was classified as following 1 of 4 patterns. These 4 patterns were then compared by using a mixed-model analysis of variance. The biomechanical variables that were compared were cadence, peak and rate of rise of the resultant force, mechanical effective force, push angle, and ratio of time spent pushing to time in recovery. RESULTS: The most common propulsive stroke involved the user lifting the hand over the pushrim during the recovery phase. The stroke pattern was independent of axle position and varied from side to side and between speeds. After controlling for subject characteristics, significant differences were observed between stroke patterns in cadence and ratio of time spent pushing to time in recovery. A stroke pattern that involves using a semicircular motion with the hand below the pushrim during the recovery phase of the propulsion stroke was associated with a lower cadence and more time spent in the push phase relative to the recovery phase. CONCLUSION: The semicircular motion of propulsion displayed characteristics consistent with reduced repetition and more efficient propulsion. Use of this propulsion style may reduce trauma to the upper extremities. Clinicians should consider training individuals in this propulsion style.     

Relation between median and ulnar nerve function and wrist kinematics during wheelchair propulsion

OBJECTIVE: To investigate the relation between median and ulnar nerve health and wrist kinematics in wheelchair users. DESIGN: Case series. SETTING: Biomechanics laboratory and electrodiagnostic laboratory at a Veterans Health Administration medical center and a university hospital, respectively. PARTICIPANTS: Thirty-five people with spinal cord injury who use manual wheelchairs. INTERVENTION: Subjects propelled their own wheelchair on a dynamometer at 0.9 and 1.8m/s. Bilateral biomechanic data were obtained by using force and moment sensing pushrims and a kinematic system. Bilateral median and ulnar nerve conduction studies were also completed. MAIN OUTCOME MEASURES: Wrist flexion, extension, radial and ulnar deviation peaks, and ranges of motion (ROMs) as related to median and ulnar motor and sensory amplitudes. A secondary analysis included peak pushrim forces and moments and stroke frequency. RESULTS: There was a significant, positive correlation between flexion and extension ROM and both ulnar motor amplitude (r=.383, P<.05) and median motor amplitude (r=.361, P<.05). CONCLUSIONS: Contrary to our hypothesis, subjects using a greater ROM showed better nerve function than subjects propelling with a smaller ROM. Subjects using a larger ROM used less force and fewer strokes to propel their wheelchairs at a given speed. It is possible that long, smooth strokes may benefit nerve health in manual wheelchair users.     

The effect of rear wheel camber in manual wheelchair propulsion

Eight nonimpaired subjects participated in a wheelchair exercise test using a motor-driven treadmill in order to study the effect of rear wheel camber on wheelchair ambulation. The test consisted of four runs with rear wheels in 0, 3, 6, and 9 degrees camber at four speed steps of 2, 3, 4, and 5 km/hr. There were no significant effects upon oxygen cost, heart rate, and mechanical efficiency. The kinematic parameters of push time, push angle, and abduction showed differences between 3 and 6 degrees camber. The relationship between the findings, using surface EMG results for six shoulder muscles, is discussed. For one subject, data were extended to study the angular velocities of shoulder and elbow.     

Glenohumeral joint kinematics and kinetics for three coordinate system representations during wheelchair propulsion.

The shoulder plays a very important role during manual wheelchair propulsion. Unfortunately, substantial numbers of manual wheelchair users eventually develop shoulder injury or pain. Recently, studies have begun to investigate the etiology of wheelchair user shoulder injuries. This study compared three coordinate systems used to represent the shoulder during wheelchair propulsion. Our results show statistically significant differences between the three shoulder representations analyzed. Differences are seen for individuals and for the subjects as a group. Based upon our results, the fixed-z model appears preferable over the other representations due to its simplicity, low hardware requirements, and the similarity of the results to the free representation. This article also provides some insight into maximal shoulder joint forces and moments recorded during manual wheelchair propulsion. Future work should include more sophisticated models of the shoulder complex.