Paralyzed Veterans of America Consortium for Spinal Cord Medicine. Preservation of upper limb function following spinal cord injury: a clinical practice guideline for health-care professionals

Effect of wheelchair frame material on users' mechanical work and transmitted vibration

Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO 2631-1:1997. Reducing the mechanical work required to travel a given distance (WN-WPM, weight-normalized work-per-meter) can help reduce the risk of shoulder injury, while reducing the vibration transmissibility (VT) of the wheelchair frame can reduce whole-body vibration. New materials such as titanium and carbon are used in today's wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs (1 titanium, 1 carbon, and 4 aluminium). Ten able-bodied users propelled the six wheelchairs on three ground surfaces. Although no significant difference of WN-WPM was found between wheelchairs (P < 0.1), significant differences of VT were found (P < 0.05). The carbon wheelchair had the lowest VT. Contrarily to current belief, the titanium wheelchair VT was similar to aluminium wheelchairs. A negative correlation between VT and WN-WPM was found, which means that reducing VT may be at the expense of increasing WN-WPM. Based on our results, use of carbon in wheelchair construction seems promising to reduce VT without increasing WN-WPM.

Wheelchair appropriateness in patients with spinal cord injury: a Turkish experience

STUDY DESIGN

Descriptive.

OBJECTIVE

To determine the wheelchair appropriateness in patients with spinal cord injury (SCI).

SETTING

National Rehabilitation Center in Ankara, Turkey.

METHODS

Twenty-seven (25 male, 2 female) SCI patients were included. Demographic and clinical characteristics of the patients were noted. All wheelchairs were evaluated considering each part (seat length, seat depth, seat height, back height, armrest, headrest, wheels and seat belt) by a physiatrist who had attended the wheelchair-training course. The wheelchair was declared as inappropriate if at least three parts of wheelchair were not appropriate.

RESULTS

The mean age of the patients was 32.9±9.3 years and mean duration of wheelchair use was 19.63±23.02 months. Among the patients, 21 (77.8%) were American Spinal Injury Association Impairment Scale (AIS) A, 4 (3.7%) AIS B, 1 (3.7%) AIS C and 1 (3.7%) AIS D. Five (18.5%) wheelchairs were motorized and 22 (81.5%) were manual. Overall, 15 (55.6%) wheelchairs were inappropriate. Seat height, cushion and back height were the most common inappropriate parts.

CONCLUSION

In light of our first and preliminary results, we can argue that 55% of the patients with SCI use inappropriate wheelchairs. In order to achieve better mobility; personally designed wheelchairs should be prescribed by the clinicians.

The relationship between independent transfer skills and upper limb kinetics in wheelchair users

Transfers are one of the most physically demanding wheelchair activities. The purpose of this study was to determine if using proper transfer skills as measured by the Transfer Assessment Instrument (TAI) is associated with reduced loading on the upper extremities. Twenty-three wheelchair users performed transfers to a level-height bench while a series of forces plates, load cells, and a motion capture system recorded the biomechanics of their natural transferring techniques. Their transfer skills were simultaneously evaluated by two study clinicians using the TAI. Logistic regression and multiple linear regression models were used to determine the relationships between TAI scores and the kinetic variables on both arms across all joints. The results showed that the TAI measured transfer skills were closely associated with the magnitude and timing of joint moments (P < .02, model R(2) values ranged from 0.27 to 0.79). Proper completion of the skills which targeted the trailing arm was associated with lower average resultant moments and rates of rise of resultant moments at the trailing shoulder and/or elbow. Some skills involving the leading side had the effect of increasing the magnitude or rate loading on the leading side. Knowledge of the kinetic outcomes associated with each skill may help users to achieve the best load-relieving effects for their upper extremities.

Effects of repetitive shoulder activity on the subacromial space in manual wheelchair users

This study investigated (1) the effect of repetitive weight-relief raises (WR) and shoulder external rotation (ER) on the acromiohumeral distance (AHD) among manual wheelchair users (MWUs) and (2) the relationship between shoulder pain, subject characteristics, and AHD changes. Twenty-three MWUs underwent ultrasound imaging of the nondominant shoulder in an unloaded baseline position and while holding a WR position before and after the WR/ER tasks. Paired t-tests and Spearman correlational analysis were used to assess differences in the AHD before and after each task and the relationships between pain, subject characteristics, and the AHD measures. A significant reduction in the subacromial space (P<0.01) occurred when subjects performed a WR position compared to baseline. Individuals with increased years of disability had greater AHD percentage narrowing after WR (P=0.008). Increased shoulder pain was associated with AHD percentage narrowing after ER (P≤0.007). The results support clinical practice guidelines that recommend MWUs limit WR to preserve shoulder function. The isolated repetitive shoulder activity did not contribute to the changes of subacromial space in MWUs. The ultrasonographic measurement of the AHD may be a target for identifying future interventions that prevent pain.

Temporal parameters estimation for wheelchair propulsion using wearable sensors

Due to lower limb paralysis, individuals with spinal cord injury (SCI) rely on their upper limbs for mobility. The prevalence of upper extremity pain and injury is high among this population. We evaluated the performance of three triaxis accelerometers placed on the upper arm, wrist, and under the wheelchair, to estimate temporal parameters of wheelchair propulsion. Twenty-six participants with SCI were asked to push their wheelchair equipped with a SMART^Wheel. The estimated stroke number was compared with the criterion from video observations and the estimated push frequency was compared with the criterion from the SMART^Wheel. Mean absolute errors (MAE) and mean absolute percentage of error (MAPE) were calculated. Intraclass correlation coefficients and Bland-Altman plots were used to assess the agreement. Results showed reasonable accuracies especially using the accelerometer placed on the upper arm where the MAPE was 8.0% for stroke number and 12.9% for push frequency. The ICC was 0.994 for stroke number and 0.916 for push frequency. The wrist and seat accelerometer showed lower accuracy with a MAPE for the stroke number of 10.8% and 13.4% and ICC of 0.990 and 0.984, respectively. Results suggested that accelerometers could be an option for monitoring temporal parameters of wheelchair propulsion.

Evaluation of lightweight wheelchairs using ANSI/RESNA testing standards

Lightweight wheelchairs are characterized by their low cost and limited range of adjustment. Our study evaluated three different folding lightweight wheelchair models using the American National Standards Institute/Rehabilitation Engineering Society of North America (ANSI/RESNA) standards to see whether quality had improved since the previous data were reported. On the basis of reports of increasing breakdown rates in the community, we hypothesized that the quality of these wheelchairs had declined. Seven of the nine wheelchairs tested failed to pass the multidrum test durability requirements. An average of 194,502 +/- 172,668 equivalent cycles was completed, which is similar to the previous test results and far below the 400,000 minimum required to pass the ANSI/RESNA requirements. This was also significantly worse than the test results for aluminum ultralight folding wheelchairs. Overall, our results uncovered some disturbing issues with these wheelchairs and suggest that manufacturers should put more effort into this category to improve quality. To improve the durability of lightweight wheelchairs, we suggested that stronger regulations be developed that require wheelchairs to be tested by independent and certified test laboratories. We also proposed a wheelchair rating system based on the National Highway Transportation Safety Administration vehicle crash ratings to assist clinicians and end users when comparing the durability of different wheelchairs.

Aspects of manual wheelchair configuration affecting mobility: a review

Many aspects relating to equipment configuration affect users' actions in a manual wheelchair, determining the overall mobility performance. Since the equipment components and configuration determine both stability and mobility efficiency, configuring the wheelchair with the most appropriate set-up for individual users' needs is a difficult task. Several studies have shown the importance of seat/backrest assembly and the relative position of the rear wheels to the user in terms of the kinetics and kinematics of manual propulsion. More recently, new studies have brought to light evidence on the inertial properties of different wheelchair configurations. Further new studies have highlighted the handrim as a key component of wheelchair assembly, since it is the interface through which the user drives the chair. In light of the new evidence on wheelchair mechanics and propulsion kinetics and kinematics, this article presents a review of the most important aspects of wheelchair configuration that affect the users' actions and mobility.

Inter-individual differences in the initial 80 minutes of motor learning of handrim wheelchair propulsion

Handrim wheelchair propulsion is a cyclic skill that needs to be learned during rehabilitation. Yet it is unclear how inter-individual differences in motor learning impact wheelchair propulsion practice. Therefore we studied how early-identified motor learning styles in novice able-bodied participants impact the outcome of a low-intensity wheelchair-practice intervention. Over a 12-minute pre-test, 39 participants were split in two groups based on a relative 10% increase in mechanical efficiency. Following the pretest the participants continued one of four different low-intensity wheelchair practice interventions, yet all performed in the same trial-setup with a total 80-minute dose at 1.11 m/s at 0.20 W/kg. Instead of focusing on the effect of the different interventions, we focused on differences in motor learning between participants over the intervention. Twenty-six participants started the pretest with a lower mechanical efficiency and a less optimal propulsion technique, but showed a fast improvement during the first 12 minutes and this effect continued over the 80 minutes of practice. Eventually these initially fast improvers benefitted more from the given practice indicated by a better propulsion technique (like reduced frequency and increased stroke angle) and a higher mechanical efficiency. The initially fast improvers also had a higher intra-individual variability in the pre and posttest, which possibly relates to the increased motor learning of the initially fast improvers. Further exploration of the common characteristics of different types of learners will help to better tailor rehabilitation to the needs of wheelchair-dependent persons and improve our understanding of cyclic motor learning processes.

Prevalence of carpal tunnel syndrome and wrist osteoarthritis in long-term paraplegic patients compared with controls

We compared functional and structural changes in the hands, in particular the prevalence of carpal tunnel syndrome, in 56 paraplegic patients who had been wheelchair dependent for over 25 years with a group of able-bodied volunteers (with matching criteria for gender and age). The hands were assessed by clinical examination, electrophysiology, disabilities of the arm shoulder and hand score and magnetic resonance imaging. Hand function was worse and wrist pain was experienced more often in the paraplegic patients, and they also had a significantly higher prevalence of carpal tunnel syndrome both clinically and electrophysiologically. The prevalence of wrist and trapeziometacarpal osteoarthritis was significantly higher in the right hand.

Using a mobility assistance dog reduces upper limb effort during manual wheelchair ramp ascent in an individual with spinal cord injury

OBJECTIVE

To compare the mechanical and muscular efforts generated in the non-dominant upper limb (U/L) when ascending a ramp with and without the use of a mobility assistance dog (AD(Mob)) in a manual wheelchair user with a spinal cord injury.

METHOD

The participant ascended a ramp at natural speed using his personal wheelchair with (three trials) and without (three trials) his AD(Mob). Movement parameters of the wheelchair, head, trunk, and non-dominant U/L (i.e. hand, forearm, and arm segments) were recorded with a motion analysis system. The orthogonal force components applied on the hand rims by the U/Ls were computed with instrumented wheels. Muscular activity data of the clavicular fibers of the pectoralis major, the anterior fibers of the deltoid, the long head of the biceps brachii, and the long head of the triceps brachii were collected at the non-dominant U/L.

RESULTS

During uphill propulsion with the AD(Mob), the total and tangential forces applied at the non-dominant handrim, along with the rate of rise of force, were reduced while mechanical efficiency was improved compared to uphill propulsion without the AD(Mob). Similarly, the resultant net joint movements (wrist, elbow, and shoulder) and the relative muscular demands (biceps, triceps, anterior deltoid, pectoralis major) decreased during uphill propulsion with an AD(Mob) versus without an AD(Mob).

CONCLUSION

Propelling uphill with the assistance of an AD(Mob) reduces U/L efforts and improves efficiency compared to propelling uphill without its assistance in a manual wheelchair user with a spinal cord injury.

Ascending curbs of progressively higher height increases forward trunk flexion along with upper extremity mechanical and muscular demands in manual wheelchair users with a spinal cord injury

High upper extremity (U/E) demands are required when manual wheelchair users (MWUs) with spinal cord injury (SCI) ascend curbs; this may contribute to the risk of developing U/E musculoskeletal impairments. The aim of this study was to compare movement strategies (kinematics), mechanical loads (kinetics) and muscular demand (EMG) at the non-dominant U/E among 15 MWUs with SCI when ascending curbs of 4 cm (3 trials), 8 cm (3 trials) and 12 cm high (3 trials) from a starting line set 3 m before the curb. Biomechanical data was collected during three trials for each height. The curb ascent task was divided into three adjustment phases: caster pop, rear-wheel ascent and post-ascent. The greatest effort was generated by the shoulder flexors and internal rotators as well as the elbow flexors. A significant difference (p < 0.0167) between the curb heights was found for most outcome measures studied: movement excursion, net joint moments and muscular utilization ratio (MUR) of the main muscles increased with the higher curb heights, mainly around the shoulder joint. These results provide insight that aside from adhering to a highly structured training method for wheelchair curb ascent, rehabilitation professionals need to propose task-specific strength training programs based on the demands documented in this study and continue to advocate for physically accessible environments.

Patterns of shoulder muscle coordination vary between wheelchair propulsion techniques

This study investigated changes in the coordination patterns of shoulder muscles and wheelchair kinetics with different propulsion techniques by comparing wheelchair users' self-selected propulsion patterns with a semicircular pattern adopted after instruction. Wheelchair kinetics data were recorded by Smart(Wheel) on an ergometer, while EMG activity of seven muscles was recorded with surface electrodes on 15 able-bodied inexperienced participants. The performance data in two sessions, first using a self-selected and then the learned semicircular pattern, were compared with a paired t-test. Muscle coordination patterns across seven muscles were analyzed by principal component analysis. The semicircular pattern was characterized by significantly lower push frequency, significantly longer push length, push duration and push distance (p < 0.05, all cases) without a significant increase in push force, when compared with the self-selected pattern. In addition, our results show that in the semicircular propulsion technique, synergistic muscles were recruited in distinct phases and displayed a clearer separation between activities in the push phase and recovery phase muscles. An instruction session in semicircular propulsion technique is recommended for the initial use of a wheelchair after an injury.

Physical activity classification utilizing SenseWear activity monitor in manual wheelchair users with spinal cord injury

STUDY DESIGN

Validation.

OBJECTIVES

The primary aim of this study was to develop and evaluate activity classification algorithms for a multisensor-based SenseWear (SW) activity monitor that can recognize wheelchair-related activities performed by manual wheelchair users (MWUs) with spinal cord injury (SCI). The secondary aim was to evaluate how the accuracy in activity classification affects the estimation of energy expenditure (EE) in MWUs with SCI.

SETTING

University-based laboratory.

METHODS

Forty-five MWUs with SCI wore a SW on their upper arm and participated in resting, wheelchair propulsion, arm-ergometery and deskwork activities. The investigators annotated the start and end of each activity trial while the SW collected multisensor data and a portable metabolic cart collected criterion EE. Three methods including linear discriminant analysis, quadratic discriminant analysis (QDA), and Naïve Bayes (NB) were used to develop classification algorithms for four activities based on the training data set from 36 subjects.

RESULTS

The classification accuracy was 96.3% for QDA and 94.8% for NB when the classification algorithms were tested on the validation data set from nine subjects. The average EE estimation errors using the activity-specific EE prediction model were 5.3±21.5% and 4.6±22.8% when the QDA and NB classification algorithms were applied, respectively, as opposed to 4.9±20.7% when 100% classification accuracy was assumed.

CONCLUSION

The high classification accuracy and low EE estimation errors suggest that the SW can be used by researchers and clinicians to classify and estimate the EE for the four activities tested in this study among MWUs with SCI.

A theoretical analysis of the influence of wheelchair seat position on upper extremity demand

BACKGROUND

The high physical demands placed on the upper extremity during manual wheelchair propulsion can lead to pain and overuse injuries that further reduce user independence and quality of life. Seat position is an adjustable parameter that can influence the mechanical loads placed on the upper extremity. The purpose of this study was to use a musculoskeletal model and forward dynamics simulations of wheelchair propulsion to identify the optimal seat position that minimizes various measures of upper extremity demand including muscle stress, co-contraction and metabolic cost.

METHODS

Forward dynamics simulations of wheelchair propulsion were generated across a range of feasible seat positions by minimizing the change in handrim forces and muscle-produced joint moments. Resulting muscle stress, co-contraction and metabolic cost were examined to determine the optimal seat position that minimized these values.

FINDINGS

Muscle stress and metabolic cost were near minimal values at superior/inferior positions corresponding to top-dead-center elbow angles between 110 and 120° while at an anterior/posterior position with a hub-shoulder angle between -10 and -2.5°. This coincided with a reduction in the level of muscle co-contraction, primarily at the glenohumeral joint.

INTERPRETATION

Deviations from this position lead to increased co-contraction to maintain a stable, smooth propulsive stroke, which consequentially increases upper extremity demand. These results agree with previous clinical guidelines for positioning the seat to reduce upper extremity overuse injuries and pain for wheelchair users.

Pushrim kinetics during advanced wheelchair skills in manual wheelchair users with spinal cord injury

OBJECTIVE

To assess the peak force during wheelchair propulsion of individuals with spinal cord injury propelling over obstacles from the Wheelchair Skills Test.

PARTICIPANTS/METHODS

Twenty-three individuals with spinal cord injury (SCI) who are full-time manual wheelchair users were included in this prospective study. A SmartWheel (Three Rivers Holdings, LLC) was used to analyze each push while subjects negotiated standardized obstacles used in the Wheelchair Skills Test, including tile, carpet, soft surface, 5° and 10° ramps, 2 cm, 5 cm, and 15 cm curbs.

RESULTS

When the peak forces of the advanced skills were compared to level 10 m tile/10 m carpet, there was a statistically significant increase in all peak forces (P value ranged from .0001 to .0268).

DISCUSSION

It is well documented that a large number of individuals with SCI develop upper limb pain. One of the recommendations to preserve the upper limb is to minimize force during repetitive tasks.

CONCLUSION

Advanced wheelchair skills require an increase in force to accomplish. The increase in forces ranged from 18% to 130% over that required for level 10 m tile/10 m carpet.

Recommendations for mobility in children with spinal cord injury

BACKGROUND

Mobility is an important aspect of the rehabilitation of children with spinal cord injury (SCI), is a necessary component of life, and is critical in a child's development. Depending upon the individual's age and degree of neurological impairment, the nature of mobility may vary.

OBJECTIVES

The objective of this article is to establish recommendations surrounding the selection of mobility for children with SCI.

METHODS

Extensive literature review and multidisciplinary peer review.

RESULTS

Types of mobility including power, manual, upright, and community are discussed, and recommendations are made based on medical necessity, neurological level, ASIA Impairment Scale score, and developmental considerations and challenges.

CONCLUSION

Mobility is critical for proper development to occur in the pediatric population, and it may be challenging to make recommendations for mobility in children with SCI. It is essential for clinicians providing care to children with SCI to address mobility in a comprehensive and longitudinal manner across the children's environments.

The influence of wheelchair propulsion technique on upper extremity muscle demand: a simulation study

BACKGROUND

The majority of manual wheelchair users will experience upper extremity injuries or pain, in part due to the high force requirements, repetitive motion and extreme joint postures associated with wheelchair propulsion. Recent studies have identified cadence, contact angle and peak force as important factors for reducing upper extremity demand during propulsion. However, studies often make comparisons between populations (e.g., able-bodied vs. paraplegic) or do not investigate specific measures of upper extremity demand. The purpose of this study was to use a musculoskeletal model and forward dynamics simulations of wheelchair propulsion to investigate how altering cadence, peak force and contact angle influence individual muscle demand.

METHODS

Forward dynamics simulations of wheelchair propulsion were generated to emulate group-averaged experimental data during four conditions: 1) self-selected propulsion technique, and while 2) minimizing cadence, 3) maximizing contact angle, and 4) minimizing peak force using biofeedback. Simulations were used to determine individual muscle mechanical power and stress as measures of muscle demand.

RESULTS

Minimizing peak force and cadence had the lowest muscle power requirements. However, minimizing peak force increased cadence and recovery power, while minimizing cadence increased average muscle stress. Maximizing contact angle increased muscle stress and had the highest muscle power requirements.

INTERPRETATION

Minimizing cadence appears to have the most potential for reducing muscle demand and fatigue, which could decrease upper extremity injuries and pain. However, altering any of these variables to extreme values appears to be less effective; instead small to moderate changes may better reduce overall muscle demand.

Persistent polyuria in a rat spinal contusion model

Polyuria contributes to bladder overdistention, which confounds both lower and upper urinary tract management in individuals having a spinal cord injury (SCI). Bladder overdistention post-SCI is one of the most common triggers for autonomic dysreflexia, a potentially life-threatening condition. Post-SCI polyuria is thought to result from loss of vascular tone in the lower extremities, leading to edema and subsequent excess fluid, resulting in polyuria. Mild SCIs that have near complete recovery would therefore be expected to have little to no polyuria, while severe injuries resulting in flaccid limbs and lower extremity edema would be expected to exhibit severe polyuria. Since interventions that may decrease lower extremity edema are recommended to lessen the severity of polyuria, step training (which promotes vascular circulation) was evaluated as a therapy to reduce post-SCI polyuria. In the present study, polyuria was evaluated in mild, moderate, and severe contusive SCI in adult male rats. The animals were housed in metabolic cages for 24-hour periods pre- and post-SCI (to 6 weeks). Urine, feces, food, water, and body weights were collected. Other assessments included residual expressed urine volumes, locomotor scoring, in-cage activity, and lesion histology. SCI produced an immediate increase in 24-hour urine collection, as early as 3 days post-SCI. Approximately 2.6-fold increases in urine collection occurred from weeks 1-6 post-SCI for all injury severities. Even with substantial gains in locomotor and bladder function following a mild SCI, polyuria remained severe. Step training (30 min/day, 6 days/week) did not alleviate polyuria in the moderate SCI contusion group. These results indicate that (1) mild injuries retaining weight-bearing locomotion that should have mild, if any, edema/loss of vascular tone still exhibit severe polyuria, and (2) step training was unable to reduce post-SCI polyuria. Taken together, these results indicate that the current mechanistic hypothesis of post-SCI polyuria may be incomplete.

Increases in wheelchair breakdowns, repairs, and adverse consequences for people with traumatic spinal cord injury

OBJECTIVE

The aims of this study were to report the current incidence of wheelchair breakdowns, repairs, and consequences and to compare current data with historical data.

DESIGN

A convenience sample survey of 723 participants with spinal cord injury who use a wheelchair for more than 40 hrs/wk treated at a Spinal Cord Injury Model Systems center was conducted.

RESULTS

Significant increases were found in the number of participants reporting repairs (7.8%) and adverse consequences (23.5%) in a 6-mo period (2006-2011) compared with historical data (2004-2006) (P < 0.001). When examining current data, minorities experienced a greater frequency and higher number of reported consequences (P = 0.03). Power wheelchair users reported a higher number of repairs and consequences than did manual wheelchair users (P < 0.001). Wheelchairs equipped with seat functions were associated with a greater frequency of adverse consequences (P = 0.01). Repairs did not vary across funding source, but individuals with wheelchairs provided by Medicare and Medicaid reported a higher frequency of consequences than did the combined group of the Department of Vocational Rehabilitation, Worker's Compensation, and the Veterans Administration (P = 0.034 and P = 0.013, respectively).

CONCLUSIONS

The incidence and consequences of repairs are increasing from what was already a very high statistic in this United States population. Further investigation into causality is required, and intervention is needed to reverse this potential trend.

Development of an automated method to detect sitting pivot transfer phases using biomechanical variables: toward a standardized method

Background

Sitting pivot transfer (SPT) is one of the most important, but at the same time strenuous at the upper extremity, functional task for spinal cord injured individuals. In order to better teach this task to those individuals and to improve performance, a better biomechanical understanding during the different SPT phases is a prerequisite. However, no consensus has yet been reached on how to depict the different phases of the SPT. The definition of the phases of the SPT, along with the events characterizing these phases, will facilitate the interpretation of biomechanical outcome measures related to the performance of SPTs as well as strengthen the evidence generated across studies.

Methods

Thirty-five individuals with a spinal cord injury performed two SPTs between seats of similar height using their usual SPT technique. Kinematics and kinetics were recorded using an instrumented transfer assessment system. Based on kinetic and kinematic measurements, a relative threshold-based algorithm was developed to identify four distinct phases: pre-lift, upper arm loading, lift-pivot and post-lift phases. To determine the stability of the algorithm between the two SPTs, Student t-tests for dependent samples were performed on the absolute duration of each phase.

Results

The mean total duration of the SPT was 2.00 ± 0.49 s. The mean duration of the pre-lift, upper arm loading, lift-pivot and post-lift phases were 0.74 ± 0.29 s, 0.28 ± 0.13 s, 0.72 ± 0.24 s, 0.27 ± 0.14 s whereas their relative contributions represented approximately 35%, 15%, 35% and 15% of the overall SPT cycle, respectively. No significant differences were found between the trials (p = 0.480-0.891).

Conclusion

The relative threshold-based algorithm used to automatically detect the four distinct phases of the SPT, is rapid, accurate and repeatable. A quantitative and thorough description of the precise phases of the SPT is prerequisite to better interpret biomechanical findings and measure task performance. The algorithm could also become clinically useful to refine the assessment and training of SPTs.

The effects of four different stroke patterns on manual wheelchair propulsion and upper limb muscle strain

PURPOSE

To evaluate the effects of stroke pattern on handrim biomechanics and upper limb electromyography (EMG) in experienced wheelchair users.

METHOD

Subjects propelled their own wheelchair on a level, motor-driven treadmill using each of four identified stroke patterns: arcing, double loop (DL), semi-circular (SC) and single loop (SL). Upper limb EMG and measurements taken from an instrumented wheelchair wheel were compared for each pattern. A one-way ANOVA with Bonferroni correction (p < 0.05) was used to check for significant differences.

RESULTS

The DL and SC patterns produced the best overall results. The DL pattern led to a significantly longer contact angle and significantly less braking moment than the SL and arcing patterns, and a significantly lower cadence than the SL pattern. The SC pattern led to a significantly longer contact angle than the SL pattern and the lowest peak force and impact of any pattern. There were no significant differences in integrated EMG (IEMG); however, the DL and arcing patterns produced lower combined IEMG values.

CONCLUSIONS

When traversing level terrain, wheelchair users should push with either the DL or SC patterns. Between the two, the DL pattern required less muscle activity and may be a better choice for experienced wheelchair users.

Wheelchair propulsion kinematics in beginners and expert users: influence of wheelchair settings

BACKGROUND

Biomechanical studies have linked the handrim wheelchair propulsion with a prevalence of upper limb musculoskeletal disorders. The purpose of this study was to examine the influence of the wheelchair settings on upper limb kinematics during wheelchair propulsion. Recordings were made under various wheelchair configuration conditions to understand the effect of wheelchair settings on kinematics parameters such shoulder, elbow and wrist angles.

METHODS

Ten experts and ten beginners' subjects propelled an experimental wheelchair on a roller ergometer system at a comfortable speed. Twelve wheelchair configurations were tested. Kinematics were recorded for each configuration. Based on the hand position relatively to the handrim, the main kinematic parameters of wheelchair propulsion were investigated on the whole propulsion cycle and a key event such as handrim contact and release.

FINDINGS

Compared to the beginner subjects, all the experts' subjects generally present higher joint amplitude and propulsion speeds. Seat height and antero-posterior axle position influence usage of the hand-rim, timing parameters and configurations of upper limb joints. Results seem to confirm that low and backward seat position allow a greater efficiency. Nevertheless, according that proximity of joint limit is a well known factor of musculoskeletal disorders, our results let us think that too low and backward seat position, increasing joints positions and amplitudes, could increase the risk of upper limb injuries in relation with manual wheelchair propulsion.

INTERPRETATION

Kinematic differences highlight that future studies on wheelchair propulsion should only be done with impaired experienced subjects. Furthermore, this study provides indications on how wheelchair settings can be used for upper limb injury prevention.

Resolution of tracheostomy complications by decanulation and conversion to noninvasive management for a patient with high-level tetraplegia

OBJECTIVES

To report conversion from tracheostomy (TIV) to noninvasive intermittent positive pressure ventilation (NIV) for a continuously ventilator-dependent patient with high-level spinal cord injury (SCI) with no measurable vital capacity (VC = 0 mL) to resolve tracheostomy-associated complications.

METHODS

A case report of a 38-year-old female in a chronic care facility in Japan with a 10-year history of ventilator-dependent tetraplegia (C1 ASIA-A) presented for increasing difficulty vocalizing. She had been using a fenestrated cuffed tracheostomy tube to produce speech with the cuff deflated. Speech was increasingly hypophonic, because of tracheostoma enlargement, tube migration, and tracheal granulation.

RESULTS

The NIV was provided via nasal and oral interfaces, the ostomy was surgically closed, and vocalization resumed. Airway secretions were expulsed using manually assisted coughing. The patient returned to the community.

CONCLUSION

Conversion to NIV should be considered for ventilator-dependent patients with SCI who have adequate bulbar-innervated muscle function to permit effective speech and assisted coughing.

A new design for an old concept of wheelchair pushrim

PURPOSE

Report on the development of an ergonomic manual wheelchair pushrim and evaluate the user's perception of the quality of the device.

METHOD

Based on anthropometric features and ergonomic concepts, a new wheelchair pushrim was designed, and a prototype was manufactured in polyurethane, using the rapid prototyping technique and serial production of parts by molding. The prototype was tested by a sample of wheelchair users, who rated the perceived quality of the device after testing both the new and conventional pushrims in a wheelchair propulsion experimental protocol.

RESULTS

The new ergonomic pushrim was found to be, in general, better than the conventional round tube pushrim. Specifically, experienced wheelchair users found the new wheelchair pushrim better in terms of easy and comfortable propulsion, braking and maneuvering of the wheelchair, and appearance.

CONCLUSIONS

The new wheelchair pushrim provides a proper fit for the hands due to its ergonomic design and its polyurethane composition, making wheelchair propulsion easier and more comfortable than the conventional wheelchair pushrim. Assistive technology devices should be design based on ergonomic concepts that involve less effort and offer greater comfort for the user. [Box: see text].

Is carpal tunnel release under-utilized in veterans with spinal cord injury?

OBJECTIVE

Carpal tunnel syndrome (CTS) is a common disorder among individuals with spinal cord injury (SCI). Although carpal tunnel release is highly effective, the procedure may be under-utilized in this population. This study attempts to identify if CTS is under-treated in Veterans with SCI.

DESIGN

The Veterans Affairs (VA) National Patient Care Database was used for data compilation within fiscal years 2007 and 2008. Using ICD-9-CM diagnoses codes, individuals with SCIs were identified, including those diagnosed with CTS. Current procedural terminology (CPT) codes further showed those who had undergone surgical intervention including open and endoscopic release of the transverse carpal ligament. The VA SCI cohort was compared to the general VA population with regard to demographics, diagnosis, surgical intervention, and treatment location.

RESULTS

A total of 19 296 veterans with SCI were identified within the 2-year period. The prevalence of CTS within this cohort was 3.5%, compared to 2.1% in the general VA population. The rate of transverse carpal ligament release was similar between the VA SCI cohort and general population (0.24 and 0.17%, respectively). The majority of surgical treatment (89%) occurred within the VA 'hub-and-spoke' system of SCI care.

CONCLUSION

CTS appears to be under-diagnosed and under-treated in veterans with SCI.

A synthesis of best evidence for the restoration of upper-extremity function in people with tetraplegia

PURPOSE

Because upper-limb function represents overall function for individuals with tetraplegia, the restoration of upper-extremity function is exceedingly important for this population. The purpose of this review was to identify interventions that optimize upper-limb function after tetraplegia based on best available evidence.

METHODS

A search of MEDLINE, AMED, and PubMed with the search terms "hand function AND tetraplegia" and "upper limb function AND tetraplegia" found 384 articles. After elimination of duplicates and review of titles and abstracts, 43 studies were found to be applicable. Study quality of all applicable studies was assessed with a modified version of the Scottish Intercollegiate Guidelines Network for Cohort Studies methodology.

RESULTS

The applicable studies were organized into three categories: conventional therapies (CT), electrical stimulation therapies (ES), and surgical interventions (SI). The proportion of papers in each category that presented with sufficient methodological quality to contribute to best evidence was as follows: CT: 0/2; ES: 10/21; SI: 6/20.

CONCLUSIONS

ES therapies are beneficial as assistive technologies and as therapeutic intervention in the subacute phase of recovery. SIs are suitable for individuals who meet very specific criteria for tendon-transfer surgery. Further clinical trials are warranted for ES and SI therapies to substantiate prescription of therapeutics.

Future directions for spinal cord injury research: recent developments and model systems contributions

The authors look forward and discuss future directions in spinal cord injury (SCI) from a perspective of biomedical, psychosocial and technologic research. This discussion is based both on recent developments from various fields of knowledge and, more specifically, on SCI Model Systems' research contributions to medical rehabilitation. Biomedical research, as described here, includes (1) the process of moving from the "bench to bedside" and harnessing knowledge from basic science to produce new clinical treatment options for SCI during the life span; (2) the rapid proliferation of clinical trials aimed at neurologic recovery; (3) the growth of new technologies to restore and improve function; and (4) the challenges of developing relevant outcome measures to evaluate efficacy and effectiveness of interventions. Recent progress in psychosocial research has contributed significantly to understanding of the many factors associated with disability during the life course, the importance of quality of life issues, and the value of activity, participation, and the environment in promoting successful rehabilitation outcomes following SCI. Technology and bioengineering advances are discussed in relation to access to high-quality technology; restoration and replacement of movement; and technology to enhance rehabilitation outcomes.

Comparing handrim biomechanics for treadmill and overground wheelchair propulsion

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To compare handrim biomechanics recorded during overground propulsion with those recorded during propulsion on a motor-driven treadmill.

SETTING

Biomechanics laboratory.

METHODS

In all, 28 manual wheelchair users propelled their own wheelchairs, at a self-selected speed, on a low-pile carpet and on a wheelchair accessible treadmill. Handrim biomechanics were recorded with an OptiPush instrumented wheelchair wheel.

RESULTS

Across the two conditions, all handrim biomechanics were found to be similar and highly correlated (r>0.85). Contact angle, peak force, average force and peak axle moment differed by 1.6% or less across the two conditions. Although not significant, power output and cadence tended to be slightly higher for the treadmill condition (3.5 and 3.6%, respectively), owing to limitations in adjusting the treadmill grade.

CONCLUSION

Based on the results of this study, a motor-driven treadmill can serve as a valid surrogate for overground studies of wheelchair propulsion.

Effect of an intense wheelchair propulsion task on quantitative ultrasound of shoulder tendons

OBJECTIVE

To investigate acute ultrasound changes of biceps and supraspinatus tendon appearance after an intense wheelchair propulsion task, and how these changes relate to demographic and biomechanical risk factors.

DESIGN

A survey.

SETTING

Research laboratory and research space at the National Veterans Wheelchair Games.

PARTICIPANTS

A convenience sample of 60 manual wheelchair users were recruited through research registries and rehabilitation clinics as well as from participants at the 2007 and 2008 National Veterans Wheelchair Games. The subjects were between 18 and 65 years of age at least 1 year after injury and did not have progressive disabilities.

MAIN OUTCOME MEASURES

Quantitative ultrasound (QUS) measures of biceps and supraspinatus tendon appearance, stroke frequency, resultant force, tendinopathy score, and duration of wheelchair use.

RESULTS

Biceps tendon appearance after an intense propulsion task was significantly related to chronic biceps tendinopathy, duration of wheelchair use, stroke frequency, and resultant force. The subjects with a higher stroke frequency or resultant force tended to have a brighter, more organized tendon appearance compared with the prepropulsion imaging session (baseline). The subjects with tendinopathy or a longer duration of wheelchair use were more likely to have a darker, diffuse tendon appearance immediately after the propulsion task. Supraspinatus tendon appearance after propulsion was only significantly predicted by baseline QUS measures.

CONCLUSIONS

QUS has proven to be sensitive to risk factors for tendon pathology. Future studies can apply grayscale-based QUS to study the development and prevention of repetitive strain injuries, particularly on an individual basis.

Long-term outcomes of adults with pediatric-onset spinal cord injuries as a function of neurological impairment

OBJECTIVE

To identify outcomes of participation, life satisfaction, and medical complications as a function of impairment in adults with pediatric-onset spinal cord injury (SCI).

METHODS

Study participants were adults who sustained SCI at age 18 years or younger and were interviewed at age 24 years or older (M = 26.9, SD = 3.5). The telephone interview included a questionnaire and several standardized measures: FIM instrument (FIM), Craig Handicap Assessment and Reporting Technique (CHART), SF-12 Health Survey, and Satisfaction with Life Scale. Using the International Standards for Neurological Classification of Spinal Cord Injury and the American Spinal Injury Association (ASIA) Impairment Scale (AIS), subjects were grouped into four impairment categories: C1-C4 ABC, C5-C8 ABC, T1-L4 ABC, and AIS D.

RESULTS

Of the 410 participants, 62% were male, 54% had tetraplegia, 70% had AIS A lesions, and average age at injury was 14 years (SD = 4.3). Of the 407 subjects who had complete neurological information, 59 had C1-C4 ABC, 140 had C5-C8 ABC, 168 had T1-L4 ABC, and 40 had AIS D lesions. The outcomes were delineated for education, employment, independent living and driving, marriage, participation, medical complications, health-related quality of life, and global life satisfaction, in addition to the ASIA motor score and FIM motor scores, for each of the four impairment groups.

CONCLUSIONS

This information should help focus interventions that facilitate positive outcomes in relationship to the severity of impairment. In addition, these data can provide a level of expectation about long-term outcomes for newly injured children and their parents.

Hand rim wheelchair propulsion training using biomechanical real-time visual feedback based on motor learning theory principles

BACKGROUND/OBJECTIVE

As considerable progress has been made in laboratory-based assessment of manual wheelchair propulsion biomechanics, the necessity to translate this knowledge into new clinical tools and treatment programs becomes imperative. The objective of this study was to describe the development of a manual wheelchair propulsion training program aimed to promote the development of an efficient propulsion technique among long-term manual wheelchair users.

METHODS

Motor learning theory principles were applied to the design of biomechanical feedback-based learning software, which allows for random discontinuous real-time visual presentation of key spatiotemporal and kinetic parameters. This software was used to train a long-term wheelchair user on a dynamometer during 3 low-intensity wheelchair propulsion training sessions over a 3-week period. Biomechanical measures were recorded with a SmartWheel during over ground propulsion on a 50-m level tile surface at baseline and 3 months after baseline.

RESULTS

Training software was refined and administered to a participant who was able to improve his propulsion technique by increasing contact angle while simultaneously reducing stroke cadence, mean resultant force, peak and mean moment out of plane, and peak rate of rise of force applied to the pushrim after training.

CONCLUSIONS

The proposed propulsion training protocol may lead to favorable changes in manual wheelchair propulsion technique. These changes could limit or prevent upper limb injuries among manual wheelchair users. In addition, many of the motor learning theory-based techniques examined in this study could be applied to training individuals in various stages of rehabilitation to optimize propulsion early on.

Effects of hand cycle training on physical capacity in individuals with tetraplegia: a clinical trial

BACKGROUND

Regular physical activity is important for people with tetraplegia to maintain fitness but may not always be easily integrated into daily life. In many countries, hand cycling has become a serious option for daily mobility in people with tetraplegia. However, little information exists regarding the suitability of this exercise mode for this population.

OBJECTIVE

The purpose of this study was to evaluate the effects of a structured hand cycle training program in individuals with chronic tetraplegia.

DESIGN

Pretraining and posttraining outcome measurements of physical capacity were compared.

SETTING

Structured hand cycle interval training was conducted at home or in a rehabilitation center in the Netherlands.

PARTICIPANTS

Twenty-two patients with tetraplegia (American Spinal Injury Association Impairment Scale classification A-D) at least 2 years since injury participated.

INTERVENTION

The intervention was an 8- to 12-week hand cycle interval training program.

MEASURES

Primary outcomes of physical capacity were: peak power output (POpeak) and peak oxygen uptake (Vo(2)peak), as determined in hand cycle peak exercise tests on a motor-driven treadmill. Secondary outcome measures were: peak muscle strength (force-generating capacity) of the upper extremities (as assessed by handheld dynamometry), respiratory function (forced vital capacity and peak expiratory flow) and participant-reported shoulder pain.

RESULTS

Significant improvements following a mean of 19 (SD=3) sessions of hand cycle training were found in POpeak (from 42.5 W [SD=21.9] to 50.8 W [SD=25.4]), Vo(2)peak (from 1.32 L.min(-1) [SD=0.40] to 1.43 L.min(-1) [SD=0.43]), and mechanical efficiency, as reflected by a decrease in submaximal oxygen uptake. Except for shoulder abduction strength, no significant effects were found on the secondary outcomes.

LIMITATIONS

Common health complications, such as urinary tract infections, bowel problems, and pressure sores, led to dropout and nonadherence.

CONCLUSION

Patients with tetraplegia were able to improve their physical capacity through regular hand cycle interval training, without participant-reported shoulder-arm pain or discomfort.

SMARTWheel: From concept to clinical practice

Wheelchair prescription is complex with thousands of choices and options. Theoretically, a higher quality or innovative wheelchair that is appropriately matched to the user and their unique needs will increase participation. It is well accepted that there is an alarmingly high incidence of carpal tunnel syndrome, and rotator cuff injuries among manual wheelchair users. Since the initial conceptualization, the SMART(Wheel) was intended to better understand the physiological and physical effects of wheelchair propulsion on the body. Initially, little was known about wheelchair propulsion and the SMART(Wheel) transformed the nascent field of wheelchair propulsion biomechanics. Although still an important area of clinical research, the SMART(Wheel) has been critical to the study of the relationship between the type of wheelchair, set-up, activity, technique, anatomy, and physiology and repetitive strain injury. There has been growing evidence that the wheelchair-user interaction explains a substantial portion of the risk of developing a degenerative injury and on community participation. A noteworthy contribution of this work was the release of the clinical practice guideline, entitled, Preservation of Upper Limb Function Following Spinal Cord Injury in 2005. The SMART(Wheel) has been used by other scientists in areas that were not originally envisioned to be applications. It has been used to support the design of tools for developing a trail mapping rating and description system. It has also supported the design of accessible pedestrian walkways standards, accessible playground surfaces, and to evaluate carpets for wheelchair accessibility. It is likely that there are more new areas of exploration to emerge. This article describes the evolution of the SMART(Wheel) as new technologies became available and its applications in the field of wheelchair biomechanics and clinical service delivery.

Protection and repair of the injured spinal cord: a review of completed, ongoing, and planned clinical trials for acute spinal cord injury

Over the past 2 decades, advances in understanding the pathophysiology of spinal cord injury (SCI) have stimulated the recent emergence of several therapeutic strategies that are being examined in Phase I/II clinical trials. Ten randomized controlled trials examining methylprednisolone sodium succinate, tirilizad mesylate, monosialotetrahexosylganglioside, thyrotropin releasing hormone, gacyclidine, naloxone, and nimodipine have been completed. Although the primary outcomes in these trials were laregely negative, a secondary analysis of the North American Spinal Cord Injury Study II demonstrated that when administered within 8 hours of injury, methylprednisolone sodium succinate was associated with modest clinical benefits, which need to be weighed against potential complications. Thyrotropin releasing hormone (Phase II trial) and monosialotetrahexosylganglioside (Phase II and III trials) also showed some promise, but we are unaware of plans for future trials with these agents. These studies have, however, yielded many insights into the conduct of clinical trials for SCI. Several current or planned clinical trials are exploring interventions such as early surgical decompression (Surgical Treatment of Acute Spinal Cord Injury Study) and electrical field stimulation, neuroprotective strategies such as riluzole and minocycline, the inactivation of myelin inhibition by blocking Nogo and Rho, and the transplantation of various cellular substrates into the injured cord. Unfortunately, some experimental and poorly characterized SCI therapies are being offered outside a formal investigational structure, which will yield findings of limited scientific value and risk harm to patients with SCI who are understandably desperate for any intervention that might improve their function. Taken together, recent advances suggest that optimism for patients and clinicians alike is justified, as there is real hope that several safe and effective therapies for SCI may become available over the next decade.

Redefining the manual wheelchair stroke cycle: identification and impact of nonpropulsive pushrim contact

OBJECTIVES

To create a comprehensive definition of the manual wheelchair stroke cycle, which includes multiple periods of pushrim contact, and to show its improved clinical benefit to wheelchair propulsion analyses.

DESIGN

Cross-sectional biomechanics study.

SETTING

Three motion analysis laboratories.

PARTICIPANTS

Persons (N=54) with paraplegia who use a manual wheelchair.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Pushrim forces, axle moments, and contact angles measured during wheelchair propulsion.

RESULTS

Total force on the pushrim was used to define pushrim contact and positive axle moment was used to identify the included period of propulsive contact. During most strokes, periods of nonpropulsive contact existed before and after propulsive contact. Within these periods, braking moments were applied to the pushrim, resulting in negative power output, or power loss. Including nonpropulsive data decreased mean stroke moment and power. The magnitude and the angle over which braking moments and power loss occurred increased with wheel speed. Mean braking moment and power loss within the initial contact period were significantly (P<.001) related to stroke pattern.

CONCLUSIONS

The proposed definition of the stroke cycle provides a thorough and practical description of wheelchair propulsion. Researchers and clinicians should use this definition to understand and minimize the impact of nonpropulsive contact throughout the stroke.

Shoulder biomechanics during the push phase of wheelchair propulsion: a multisite study of persons with paraplegia

OBJECTIVES

To present a descriptive analysis and comparison of shoulder kinetics and kinematics during wheelchair propulsion at multiple speeds (self-selected and steady-state target speeds) for a large group of manual wheelchair users with paraplegia while also investigating the effect of pain and subject demographics on propulsion.

DESIGN

Case series.

SETTING

Three biomechanics laboratories at research institutions.

PARTICIPANTS

Volunteer sample of 61 persons with paraplegia who use a manual wheelchair for mobility.

INTERVENTION

Subjects propelled their own wheelchairs on a dynamometer at 3 speeds (self-selected, 0.9m/s, 1.8m/s) while kinetic and kinematic data were recorded.

MAIN OUTCOME MEASURES

Differences in demographics between sites, correlations between subject characteristics, comparison of demographics and biomechanics between persons with and without pain, linear regression using subject characteristics to predict shoulder biomechanics, comparison of biomechanics between speed conditions.

RESULTS

Significant increases in shoulder joint loading with increased propulsion velocity were observed. Resultant force increased from 54.4+/-13.5N during the 0.9m/s trial to 75.7+/-20.7N at 1.8m/s (P<.001). Body weight was the primary demographic variable that affected shoulder forces, whereas pain did not affect biomechanics. Peak shoulder joint loading occurs when the arm is extended and internally rotated, which may leave the shoulder at risk for injury.

CONCLUSIONS

Body-weight maintenance, as well as other interventions designed to reduce the force required to propel a wheelchair, should be implemented to reduce the prevalence of shoulder pain and injury among manual wheelchair users.

Effects of circuit resistance training on fitness attributes and upper-extremity pain in middle-aged men with paraplegia

OBJECTIVE

To examine the effects of circuit resistance exercise (CRT) training on muscle strength, endurance, anaerobic power, and shoulder pain in middle-aged men with paraplegia.

DESIGN

Repeated testing.

SETTING

Academic medical center.

PARTICIPANTS

Seven men (age range, 39-58y) with motor-complete paraplegia from T5 to T12 and confirmed shoulder pain occurring during daily activities.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Subjects underwent a 4-month CRT program using alternating resistance maneuvers and high-speed, low-resistance arm exercise. One-repetition maximal force was measured before training and monthly thereafter. Pretraining and posttraining peak oxygen uptake (Vo(2)peak) was measured by graded arm testing. Anaerobic power was measured before and after training using a 30-second Wingate Anaerobic Test. Shoulder pain was self-evaluated by an index validated for people with spinal cord injury (Wheelchair Users Shoulder Pain Index [WUSPI]).

RESULTS

Strength increases ranging from 38.6% to 59.7% were observed for all maneuvers (P range, .005-.008). Vo(2)peak increased after training by 10.4% (P=.01), and peak and average anaerobic power increased by 6% (P=.001) and 8.6% (P=.005), respectively. WUSPI scores +/- standard deviation were lowered from 31.9+/-24.8 to 5.7+/-5.9 (P=.008), with 3 of 7 subjects reporting complete resolution of shoulder pain.

CONCLUSIONS

CRT improves muscle strength, endurance, and anaerobic power of middle-aged men with paraplegia while significantly reducing their shoulder pain.