Quantification of reaction forces during sitting pivot transfers performed by individuals with spinal cord injury

Mapping wheelchair functions and their associated functional elements for stair climbing accessibility: a systematic review

PURPOSE

Wheelchair (WC) design elements are subjected to the accessibility and assistive needs of a person with locomotor disability. In order to pursue a holistic design for a stairclimbing WC, there is a need for literature review on WC functions reported for both stair climbing and plane surface movement.

METHODS

A total of 112 Research articles are reviewed for the purpose of extracting the relationship between WC design elements and the functions associated with them. Stairclimbing technologies are reviewed for their technological assessment in terms of functional elements associated with stairclimbing. Cross-functional mapping between functional elements and their dominant function is performed. Heat map for primary user needs and associated design elements is generated from cross mapping.

CONCLUSIONS

A design gap for user's functional needs is indicated from the review of literature on prototypes and products of WC. The literature in stairclimbing technology is primarily focussed on stair climbing capability and not on the other functional needs, such as safety, ride comfort, seat comfort, manoeuvrability, etc.Implications for rehabilitationFor attaining the goal of an effective rehabilitation, it is important to design and develop an assistive technology that can provide maximum accessibility and functioning for a person with disability. In case of locomotor disability, wheelchair (WC) is the most empowering tool that can assist people in both accessibility and activities of daily living. This review of literature was conducted to draw out the functions fulfilled by a WC, such as safety, comfort, propulsion for its users and the associated WC elements like seat, wheels, backrest, etc., that are required to fulfil those functions.WC being the most important technological intervention in the life of a person who cannot walk should be designed with the highest level of empathy. Therefore, each and every aspect of the user's physical and emotional needs should be catered up to the limits of engineering design. The research on stair climbing technologies has also grown exponentially, fuelled by technological growth in engineering mechanisms, ambient awareness sensors, actuators, etc. The review attempts to envelop such technologies and consolidate them on the basis of their capabilities and efficacies.The virtue of stair climbing has been realized through some novel and innovative mechanisms reviewed in this article that can be integrated with the research in field of functional elements required to carry out primary functions of a disabled person, such as safety, comfort, intuitiveness, etc. This review can help in coupling both of them in a more rational way where a designer who is designing the technology is more empathetic towards the design for accessibility. It can also help user in becoming more confident towards adapting a new assistive technology.

Upper limb electromyographic analysis of manual wheelchair transfer techniques in individuals with spinal cord injury: A systematic review

BACKGROUND AND PURPOSE

The objective of this study is to determine the upper limb muscle electromyographic (EMG) activity required during various manual wheelchair transfers in the population of spinal cord injury (SCI).

METHODS

This review included observational studies reporting the (EMG) activity of upper limb muscles during wheelchair transfers in people with SCI. We searched electronic databases and reference lists of relevant literature between 1995 and March 2022 with English language limits, yielding 3870 total articles. Two independent researchers performed data extraction and conducted quality assessment using two checklists, the Modified Downs and Blacks and National Heart, Lung, and Blood Institute for observational cohort and cross-sectional studies.

RESULTS

After eligibility screening, seven studies were included in this review. The sample size ranged from 10 to 32 participants aged 31-47 years. They assessed four types of transfers and mostly evaluated six upper limb muscles were biceps, triceps, anterior deltoid, pectoralis major, latissimus dorsi and ascending fibres of the trapezius. The peak EMG value indicated that muscle recruitment varied in both upper limbs according to the task demand, and the highest activity was seen during the lift-pivot transfer phase. Because of the data heterogeneity, a meta-analysis of study results was not feasible.

CONCLUSION

There were various ways of reporting the upper limb EMG muscle activity profile across all the included studies with a limited sample size. The crucial role of upper limb muscles during different types of manual wheelchair transfers was interpreted in this review. This is essential for predicting functional independence of individuals with SCI and warranting optimal rehabilitation strategies for wheelchair transfer skills.

Reliability of home-based remote and self-assessment of transfers using the Transfer Assessment Instrument among wheelchair users with spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To evaluate the reliability of home-based remote and self-assessment of transfer quality using the Transfer Assessment Instrument (TAI) among wheelchair users with spinal cord injury (SCI).

SETTING

Participant's home environment.

METHODS

Eighteen wheelchair users with SCI transferred from their wheelchair to a surface of their choice (bed, sofa, or bench) in their homes. During a live video conference, the transfer was recorded and evaluated live using the TAI (rater 1). Participants completed a self-assessment of their transfer using the TAI- questionnaire (TAI-Q). Two additional raters (raters 2 & 3) completed asynchronous assessments by watching recorded videos. Interrater reliability was assessed using Intraclass Coefficient Correlations (ICC) to compare rater 1 with the average of raters 2 & 3 and TAI-Q. Intrarater reliability was assessed by rater 1 completing another TAI by watching the recorded videos after a 4-week delay. Assessments were compared using paired sample t-tests and level of agreement between TAI scores was evaluated using Bland-Altman plots.

RESULTS

Moderate to good interrater and good intrarater reliability were found for the total TAI score with ICCs: 0.57-0.90 and 0.90, respectively. Moderate to good intrarater and interrater reliability were found for all TAI subscores (ICC: 0.60-0.94) except for interrater reliability of flight/landing which was poor (ICC: 0.20). Bland-Altman plots indicate no systematic bias related to the measurement of error.

CONCLUSIONS

The TAI is a reliable outcome measure for assessing the wheelchair and body setup phases of home-based transfers remotely and through self-assessment among individuals with SCI.

The influence of shoulder pain and fear of falling on level and non-level transfer technique

BACKGROUND

Level and non-level transfers are essential tasks of daily living for wheelchair users. Minimal research has examined the role of shoulder pain and fear of falling on transfer quality. The purpose of this study is to (1) examine the association between shoulder pain, fear of falling (FoF) and transfer quality and (2) explore the feasibility of assessing non-level transfers to-and-from the floor.

METHODS

Cross-sectional design was used to explore shoulder pain, FoF, and transfer quality in 30 manual wheelchair users (aged 18-42; 15 males). Participant demographic information (age, sex, race, disability, and years using wheelchair), Spinal Cord Injury-Fall Concern Scale (SCI-FCS), and Wheelchair User Shoulder Pain Index (WUSPI) was collected. Three types of transfers: (1) level, (2) uphill, and (3) floor-to-table were graded by a trained researcher using the Transfer Assessment Instrument (TAI) 3.0. Kruskal-Wallis test was used to determine differences in transfer quality based on condition. Spearman correlation was used to determine associations between demographic data, WUSPI, SCI-FCS, and transfer quality scores.

RESULTS

All participants safely completed the uphill non-level transfer; 27 safely completed the floor-to-table non-level transfer. Statistical analysis revealed no difference in TAI score across transfer conditions. Spearman correlation revealed a significant correlation between WUSPI and SCI-FCS scores (r = .68, P = .01) and WUSPI and uphill TAI scores (r = -.45, P = .01).

CONCLUSION

Increases in shoulder pain are related to decreased uphill transfer quality and increased FoF. Non-level transfers to-and-from the floor are feasible within clinical or laboratory settings.

Treatment of shoulder pain in people with spinal cord injury who use manual wheelchairs: a systematic review and meta-analysis

STUDY DESIGN

Systematic review and meta-analysis OBJECTIVES: The objective was to summarise prior research regarding the efficacy of active physiotherapy interventions and prevention strategies on shoulder pain, decreased physical function and quality of life in people with a spinal cord injury (SCI).

METHODS

A systematic literature search was conducted in CENTRAL, EMBASE (via Ovid), CINAHL and MEDLINE (via Ovid). Randomised controlled trials investigating effects of active physiotherapy interventions on shoulder pain, physical function and quality of life were included. Further, prospective cohort studies investigating effects of active physiotherapy interventions in prevention of shoulder pain and reduced physical function were included. Mean difference (MD) for pain (15 items on a 0-10 scale) and standardised mean difference (SMD) for physical function were summarised in a random effects meta-analysis.

RESULTS

Four studies on treatment (totalling 167 participants), and no studies on prevention were included. Significant and clinically meaningful improvements on shoulder pain (MD 19.06, 95% CI 5.72-32.40; I² = 65%) (scale 0-150) and physical function (SMD 0.61, 95% CI 0.27-0.94; I² = 0%) were found for active physiotherapy interventions. Only one study included quality of life, making meta-analysis inappropriate.

CONCLUSIONS

Evidence from a sparse number of studies supports active physiotherapy interventions to decrease shoulder pain and increase physical function in people with SCI who use a manual wheelchair. No studies met the criteria for prevention, highlighting a lack of research investigating prevention of shoulder pain and decreased physical function and quality of life.

Effectiveness of a Web-Based Direct-to-User Transfer Training Program: A Randomized Controlled Trial

OBJECTIVE

To determine the effectiveness of a web-based, direct-to-user transfer training program in improving transfer quality and maintaining improvements for up to 1 month after training as compared with a control group.

DESIGN

Randomized controlled trial with participants randomized to an immediate intervention group (IIG) or waitlist control group (WLCG) that received the training after a 6-month delay.

SETTING

Wherever the participants accessed the web-based training, likely the home environment.

PARTICIPANTS

Convenience sample of full-time wheelchair users (N=72; IIG, n=34; WLCG, n=38 for between-group analysis, n=48 for combined within-group analysis) with spinal cord injury or disorder who were able to independently perform a lateral scoot transfer.

INTERVENTIONS

Self-paced, web-based transfer training module.

MAIN OUTCOME MEASURES

Transfer Assessment Instrument Questionnaire (TAI-Q) score at baseline, 1 month, and 6 months postbaseline (WLCG only), immediately posttraining, and 1 month posttraining. The TAI-Q is an 18-item self-assessment that covers several aspects of a quality transfer.

RESULTS

The IIG significantly increased particpants' baseline TAI-Q score from 6.91±0.98 to 7.79±1.12 (P<.001) by 1 month posttraining. The WLCG also increased from baseline to the 1-month postbaseline assessment (from 6.52±1.13 to 7.00±1.09; P=.014), potentially from learning effects secondary to self-assessment with the TAI-Q. The extent of change over time did not differ significantly between the IIG and WLCG from baseline to 1 month (P=.169). However, significant improvements in TAI-Q scores were still evident after the training for the WLCG (P<.001). Those with a lower pretraining TAI-Q score and more shoulder pain were most likely to benefit from the training.

CONCLUSIONS

Repeated TAI-Q self-assessments likely contributed to improved transfer quality, with web-based training having an additive effect. Wheelchair users are likely to benefit from transfer training and self-assessment of transfer quality in their home environments. This has the potential to decrease injury risk while avoiding barriers to in-person training.

Intra- and Interrater Reliability of Remote Assessment of Transfers by Wheelchair Users Using the Transfer Assessment Instrument (Version 4.0)

OBJECTIVE

To evaluate the reliability, standard error of measurement, minimum detectable change, and item-level consistency of the Transfer Assessment Instrument (TAI) version 4.0 when used to evaluate transfer quality remotely.

DESIGN

Participants transferred from their wheelchair to a mat table (transfer 1), repeated this after a 10-minute delay to assess intrarater reliability (transfer 2), and repeated this 1-2 days later to assess test-retest reliability (transfer 3). Each transfer was scored in person by 4 raters and asynchronously by a remote clinician rater.

SETTING

2017 National Veterans Wheelchair Games.

PARTICIPANTS

Convenience sample of 44 full-time wheelchair users (N=44).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

TAI total score, subscores (wheelchair setup, body setup, flight/landing), and item scores (15 items).

RESULTS

Moderate to excellent reliability was found when scoring remotely for TAI total and subscores for intrarater (intraclass correlation coefficient (ICC(3,1)=0.687-0.854), test-retest (ICC(3,1)=0.695-0.836), and interrater reliability (ICC(3,5)=0.746-0.962). Remote rater total score and flight/landing subscore were greater (indicating higher transfer quality) compared to the average in-person raters (P=.021 and P=.005, respectively). There were no differences between transfers 1-3 in remote rater scores. Item-level percentage agreement between the remote rater and in-person exceeded the 75% cutoff for clinical utility for all items.

CONCLUSIONS

The TAI is a reliable outcome measure for assessing transfer technique remotely.

Estimating upper extremity joint loads of persons with spinal cord injury walking with a lower extremity powered exoskeleton and forearm crutches

Lower extremity powered exoskeletons with crutch support can provide upright mobility to persons with complete spinal cord injury (SCI); however, crutch use for balance and weight transfer may increase upper extremity (UE) joint loads and injury risk. This research presented the first exoskeleton-human musculoskeletal model to estimate upper extremity biomechanics, driven by 3D motion data of persons with complete SCI walking with an exoskeleton and crutch assistance. Forearm crutches instrumented with strain gauges, force plates, and a 3D motion capture system were used to collect kinematic and kinetic data from five persons with complete SCI while walking with the ARKE exoskeleton. Model output estimated participant upper extremity kinematics, kinetics, and crutch forces. Compared to inverse dynamic biomechanical crutch model studies of persons with incomplete SCI, exoskeleton users walked with more anterior trunk tilt and twice the shoulder flexion angle. Anterior tilt increased forces and moments at the crutch, shoulder, and elbow. Crutch floor contact periods were 30-40% longer, resulting in upper extremity joint impulses 5 to 12 times greater than previously reported. Reducing UE joint loading is important to reduce overuse injuries associated with ambulatory assistive devices. Incorporating a variable assist ankle joint or more experience with exoskeleton walking may reduce UE joint loads, and minimise injury risk. Study outcomes provide a quantitative understanding of UE dynamics during exoskeleton walking that can be used to improve device design, training, and rehabilitation.

Accessibility facilitators and barriers affecting independent wheelchair transfers in the community

PURPOSE

The purpose of this study is to identify facilitators and barriers to wheelchair transfers in the community and to identify specific places and surfaces in the community where increasing transfer accessibility could enable greater participation.

METHODS

This study enrolled 112 wheeled mobility device users who completed a survey describing barriers to independent transfers. Descriptive statistics (means, standard deviations, and percentages) were used to report the survey results.

RESULTS

The majority of subjects (≥50% of the sample) who were impacted by the following features found them to be helpful while transferring: presence of transfer aids, presence of grab bars, large enough transfer surface size, storage space for a wheeled mobility device (WMD), large amounts of space and clearance for legs and feet, soft surfaces, and enough space next to the transfer surface. Ninety percent (90.5%) felt their participation was limited when surfaces higher than their WMD were encountered. Participants also reported feeling limited in their participation due to lack of transfer accessibility at a variety of community destinations, including medical facilities (35.1%), modes of transportation (38.5-52.1%), pools and hot tubs (45.4%), dressing rooms (50.0%), amusement parks (49.1%), and boating areas (52.1%).

CONCLUSION

Improving accessibility for independent transfers in the community may support greater participation and lead to a better quality of life. Study findings provide insight into changes that would make the built environment more accessible and safer for wheelchair users who independently transfer.Implications for rehabilitationTransferring independently is one of the most physically demanding tasks for wheelchair users, and physical and environmental factors may affect transferability in the community.Identifying environmental facilitators and barriers to transfers may improve accessibility for wheelchair users, allowing for greater community participation, reduced risk of falls and injuries, and improvements to quality of life.

Reliability and Validity of the Revised Transfer Assessment Instrument

Background: Proper transfer technique is associated with improved biomechanics and decreased pain and pathology. However, many users do not use proper technique, and appropriate assessment and training are needed to address these deficits. The transfer assessment instrument (TAI) 4.0 was designed to meet those needs and improve on past versions by removing the need for clinician training, shortening administration time, and simplifying question content. Objectives: Evaluate the psychometric properties of the TAI 4.0. Methods: A convenience sample of full-time wheelchair users was scored on multiple transfers by four raters to assess interrater, intrarater, and test-retest reliability and concurrent validity of the TAI 4.0. Each user also was scored using a visual analog scale (VAS). Results: For 44 participants, the mean TAI 4.0 and VAS across all transfers were 7.58 ± 1.12 and 7.44 ± 1.78, respectively, and scores were significantly correlated (r = 0.52-0.7). VAS scores were more strongly influenced by the flight/landing and body setup phases of the transfer. There were no significant associations between TAI 4.0 score and demographics. Intraclass correlation coefficients (ICC) ranged from 0.80 to 0.85 for interrater reliability, 0.60 to 0.76 for intrarater reliability, and 0.55 to 0.76 for test-retest reliability. The minimum detectable change (MDC) for the total score ranged from 1.02 to 1.30. Conclusion: The TAI 4.0 provides reliable and valid quantitative assessment of an individual's transfer without the need for comprehensive training, as is the case with the TAI 3.0. The tool can be completed in 3 minutes (average) in a clinical setting with only a ruler and goniometer.

Upper-limb biomechanical analysis of wheelchair transfer techniques in two toilet configurations

BACKGROUND

Using proper technique is important for minimizing upper limb kinetics during wheelchair transfers. The objective of the study was to 1) evaluate the transfer techniques used during toilet transfers and 2) determine the impact of technique on upper limb joint loading for two different toilet configurations.

METHODS

Twenty-six manual wheelchair users (23 men and 3 women) performed transfers in a side and front wheelchair-toilet orientation while their habitual transfer techniques were evaluated using the Transfer Assessment Instrument. A motion analysis system and force sensors were used to record biomechanical data during the transfers.

FINDINGS

More than 20% of the participants failed to complete five transfer skills in the side setup compared to three skills in the front setup. Higher quality skills overall were associated with lower peak forces and moments in both toilet configurations (-0.68 < r < -0.40, p < 0.05). In the side setup, participants who properly placed their hands in a stable position and used proper leading handgrips had lower shoulder resultant joint forces and moments than participants who did not perform these skills correctly (p ≤ 0.04). In the front setup, positioning the wheelchair within three inches of the transfer target was associated with reduced peak trailing forces and moments across all three upper limb joints (p = 0.02).

INTERPRETATION

Transfer skills training, making toilet seats level with the wheelchair seat, positioning the wheelchair closer to the toilet and mounting grab bars in a more ideal location for persons who do sitting pivot transfers may facilitate better quality toilet transfers.

Effect of technique and transfer board use on the performance of wheelchair transfers

Transferring to and from the wheelchair seat is a necessary skill for many wheelchair users who wish to be independent of their everyday life. The performance of wheelchair transfers has been associated with the risk of falling and developing upper limb injuries. Both present a risk to the independence of the individual. Previous studies on wheelchair transfers have focused mainly on the analysis of sitting transfers performed by individuals with spinal cord injury, which only represent a small portion of the wider wheelchair users’ population. The purpose of this study is to investigate the effect of different transferring techniques (sitting, standing) and transfer board use on the ground reaction forces under the hands during transfer performance and transfer quality measured using the transfer assessment instrument (TAI). Sitting transfers displayed generally higher peak and mean reaction forces underneath both leading and trailing hands compared with the other techniques, but the difference was only significant between sitting and standing transfers. Standing transfers had significantly lower TAI scores compared with sitting transfer, potentially indicating a decreased level of safety associated with their performance. Transfer boards were only partially effective in reducing the weight born by the upper limbs and they caused only a minor reduction in the overall TAI score in comparison to sitting transfers.

Car Transfer and Wheelchair Loading Techniques in Independent Drivers with Paraplegia

Car transfers and wheelchair (WC) loading are crucial for independent community participation in persons with complete paraplegia from spinal cord injury, but are complex, physically demanding, and known to provoke shoulder pain. This study aimed to describe techniques and factors influencing car transfer and WC loading for individuals with paraplegia driving their own vehicles and using their personal WCs. Sedans were the most common vehicle driven (59%). Just over half (52%) of drivers place their right leg only into the vehicle prior to transfer. Overall, the leading hand was most frequently placed on the driver’s seat (66%) prior to transfer and the trailing hand was most often place on the WC seat (48%). Vehicle height influenced leading hand placement but not leg placement such that drivers of higher profile vehicles were more likely to place their hand on the driver’s seat than those who drove sedans. Body lift time was negatively correlated with level of injury and age and positively correlated with vehicle height and shoulder abduction strength. Drivers who transferred with their leading hand on the steering wheel had significantly higher levels of shoulder pain than those who placed their hand on the driver’s seat or overhead. The majority of participants used both hands (62%) to load their WC frame, and overall, most loaded their frame into the back (62%) vs. the front seat. Sedan drivers were more likely to load their frame into the front seat than drivers of higher profile vehicles (53 vs. 17%). Average time to load the WC frame (10.7 s) was 20% of the total WC loading time and was not related to shoulder strength, frame weight, or demographic characteristics. Those who loaded their WC frame into the back seat had significantly weaker right shoulder internal rotators. Understanding car transfers and WC loading in independent drivers is crucial to prevent shoulder pain and injury and preserve community participation.

Upper limb joint kinetics of three sitting pivot wheelchair transfer techniques in individuals with spinal cord injury

STUDY DESIGN

Repeated measures design.

OBJECTIVE

This study compared the upper extremity (UE) joint kinetics between three transfer techniques.

SETTING

Research laboratory.

METHODS

Twenty individuals with spinal cord injury performed three transfer techniques from their wheelchair to a level tub bench. Two of the techniques involved a head-hips method with leading hand position close (HH-I) and far (HH-A) from the body, and the third technique with the trunk upright (TU) and hand far from body. Motion analysis equipment recorded upper body movements and force sensors recorded their hand and feet reaction forces during the transfers.

RESULTS

Several significant differences were found between HH-A and HH-I and TU and HH-I transfers indicating that hand placement was a key factor influencing the UE joint kinetics. Peak resultant hand, elbow, and shoulder joint forces were significantly higher for the HH-A and TU techniques at the trailing arm (P < 0.036) and lower at the leading arm (P < 0.021), compared to the HH-I technique.

CONCLUSION

Always trailing with the same arm if using HH-A or TU could predispose that arm to overuse related pain and injuries. Technique training should focus on initial hand placement close to the body followed by the amount of trunk flexion needed to facilitate movement.

Shoulder Strength and Physical Activity Predictors of Shoulder Pain in People With Paraplegia From Spinal Injury: Prospective Cohort Study

BACKGROUND

Shoulder joint pain is a frequent secondary complaint for people following spinal cord injury (SCI).

OBJECTIVE

The purpose of this study was to determine predictors of shoulder joint pain in people with paraplegia.

METHODS/DESIGN

A 3-year longitudinal study was conducted. Participants were people with paraplegia who used a manual wheelchair for at least 50% of their mobility and were asymptomatic for shoulder pain at study entry. Participants were classified as having developed shoulder pain if they experienced an increase of ≥10 points on the Wheelchair User's Shoulder Pain Index in the 3-year follow-up period. Measurements of maximal isometric shoulder torques were collected at study entry (baseline), 18 months, and 3 years. Daily activity was measured using a wheelchair odometer, and self-reported daily transfer and raise frequency data were collected by telephone every 6 weeks.

RESULTS

Two hundred twenty-three participants were enrolled in the study; 39.8% developed shoulder pain over the 3-year follow-up period. Demographic variables and higher activity levels were not associated with shoulder pain onset. Baseline maximal isometric torque (normalized by body weight) in all shoulder muscle groups was 10% to 15% lower in participants who developed shoulder pain compared with those who remained pain-free. Lower shoulder adduction torque was a significant predictor of shoulder pain development (log-likelihood test=11.38), but the model explained only 7.5% of shoulder pain onset and consequently is of limited clinical utility.

LIMITATIONS

Time since SCI varied widely among participants, and transfer and raise activity was measured by participant recall.

CONCLUSIONS

Participants who developed shoulder pain had decreased muscle strength, particularly in the shoulder adductors, and lower levels of physical activity prior to the onset of shoulder pain. Neither factor was a strong predictor of shoulder pain onset.

Trunk control impairment is responsible for postural instability during quiet sitting in individuals with cervical spinal cord injury

BACKGROUND

Individuals with cervical spinal cord injury usually sustain impairments to the trunk and upper and lower limbs, resulting in compromised sitting balance. The objectives of this study were to: 1) compare postural control of individuals with cervical spinal cord injury and able-bodied individuals; and 2) investigate the effects of foot support and trunk fluctuations on postural control during sitting balance.

METHODS

Ten able-bodied individuals and six individuals with cervical spinal cord injury were asked to sit quietly during two 60s trials. The forces exerted on the seat and the foot support surfaces were measured separately using two force plates. The global centre of pressure sway was obtained from the measurements on the two force plates, and the sway for each force plate was calculated individually.

FINDINGS

Individuals with spinal cord injury had at least twice as large global and seat sways compared to able-bodied individuals, while foot support sway was not significantly different between the two groups. Comparison between global and seat sways showed that anterior-posterior velocity of global sway was larger compared to the seat sway in both groups.

INTERPRETATION

Postural control of individuals with cervical spinal cord injury was worse than that of able-bodied individuals. The trunk swayed more in individuals with spinal cord injury, while the stabilization effect of the feet did not differ between the groups. Foot support affected anterior-posterior fluctuations in both groups equally. Thus, trunk control is the dominant mechanism contributing to sitting balance in both able-bodied and spinal cord injury individuals.

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.

A palmar pressure sensor for measurement of upper limb weight bearing by the hands during transfers by paraplegics

Paraplegic patients have to effect transfer from one seat to another by using their upper limbs. In this process the hands bear almost the entire weight of the body in at least some phases of the transfer. It is desirable to train patients, especially those who are elderly and otherwise weak, to distribute their weight so as to avoid large forces being sustained on any one hand for an extended period. It is also desirable to evaluate the effectiveness of assistive devices like lower limb FES in sharing the load on the hand. This study presents a simple and versatile method of measuring palmar hand force during transfers by paraplegic patients. It is important that this force sensor should not interfere with the grasping and stabilizing properties of the hands and should permit normal transferring. The force sensor comprises an air-filled pouch or pillow that can be placed on any surface. This pneumatic sensor feels like upholstery padding on the surface on which it is placed. The sensor integrates the total pressure applied to the surface of the pouch, thereby obtaining the total force exerted by the palm/hand. The fabrication of the sensor is described, as well as the associated measurement circuit. The static calibration shows that the sensor is linear up to 350 N and the dynamic calibration shows that it has a bandwidth of 13 Hz. The sensor was fabricated using an inflated inelastic airbag attached to a pressure transducer. An automatic offset correction circuit in the preamplifier module ensures that any offset due to initial pressure or sensor drift is removed and the output is zero under no load condition. The key to this sensor arrangement is the ease of fitting it into the intended location without disturbing the existing arrangement for the subject's activities of daily living (ADL).

The influence of simulated rotator cuff tears on the risk for impingement in handbike and handrim wheelchair propulsion

BACKGROUND

Rotator cuff tears strongly affect the biomechanics of the shoulder joint in their role to regulate the joint contact force needed to prevent the joint from dislocation. The aim of this study was to investigate the influence of simulated progressed rotator cuff tears on the (in)stability of the glenohumeral joint and the risk for impingement during wheelchair and handbike propulsion.

METHODS

The Delft Shoulder and Elbow Model was used to calculate the magnitude of the glenohumeral joint reaction force and the objective function J, which is an indication of the effort needed to complete the task. Full-thickness tears were simulated by virtually removing muscles from the model.

FINDINGS

With larger cuff tears the joint reaction force was higher and more superiorly directed. Also extra muscle force was necessary to balance the external force such that the glenohumeral joint did not dislocate.

INTERPRETATION

A tear of only the supraspinatus leads only to a minor increase in muscle forces and a minor shift of the force on the glenoid, indicating that it is possible to function well with a torn supraspinatus muscle. A massive tear shifts the direction of the joint reaction force to the superior border of the glenoid, increasing the risk for impingement.

Impact of Functional Electrical Stimulation of Lower Limbs during Sitting Pivot Transfer Motion for Paraplegic People

Individuals with Spinal Cord Injury (SCI), perform Sitting Pivot Transfer (SPT) motion around fifteen times a day using upper extremities. It can lead to upper limbs pain and often shoulder complications. In this paper, we investigate the influence of Functional Electrical Stimulation (FES) on SPT motion of a paraplegic person. First, we proposed to develop a dynamic optimization method in order to predict SPT motion of an able-bodied subject. This approach has been validated by comparing the computed SPT trajectories with the ones measured during the experiment with an able-bodied subject. Then, we used the optimization tool to analyze the influence of FES on the SPT maneuver of paraplegic persons. Our results suggest that FES can decrease arm participation during the transfer motion of a paraplegic person.

Effects of sensorimotor trunk impairments on trunk and upper limb joint kinematics and kinetics during sitting pivot transfers in individuals with a spinal cord injury

BACKGROUND

Depending on the level and severity of the sensorimotor impairment in individuals with a spinal cord injury, the subsequent reduced seated postural stability and strength generating-capacity at the upper limbs could affect performance during sitting pivot transfer. This study aimed to determine the effects of sensorimotor impairments on head, trunk and upper limb movement and efforts during sitting pivot transfers.

METHODS

Twenty-six individuals with a spinal cord injury participated and were stratified in two subgroups: with (N=15) and without voluntary motor control (N=11) of their lower back and abdominal muscles. Kinematics and kinetics of sitting pivot transfer were collected using a transfer assessment system. Mean joint angles and movement amplitudes and peak and average joint moments were compared between subgroups using independent Student t-tests (P<0.05) for the weight-bearing sitting pivot transfer phases.

FINDINGS

The subgroup without voluntary control of their lower back and abdominal muscles had significantly greater forward trunk flexion compared to the other subgroup resulting in higher wrist extension and elbow flexion at both upper limbs. No significant joint moment difference was found between the subgroups.

INTERPRETATION

Individuals with spinal cord injury who have no voluntary motor control of their abdominal and lower back muscles increase forward trunk flexion during sitting pivot transfers 1) to increase stiffness of their spine that may optimize the strength-generating ability of their thoracohumeral muscles and 2) to lower their center of mass that may facilitate lift-off and enhance the overall stability during sitting pivot transfers.

Development of custom measurement system for biomechanical evaluation of independent wheelchair transfers

This study describes a new custom measurement system designed to investigate the biomechanics of sitting-pivot wheelchair transfers and assesses the reliability of selected biomechanical variables. Variables assessed include horizontal and vertical reaction forces underneath both hands and three-dimensional trunk, shoulder, and elbow range of motion. We examined the reliability of these measures between 5 consecutive transfer trials for 5 subjects with spinal cord injury and 12 nondisabled subjects while they performed a self-selected sitting pivot transfer from a wheelchair to a level bench. A majority of the biomechanical variables demonstrated moderate to excellent reliability (r > 0.6). The transfer measurement system recorded reliable and valid biomechanical data for future studies of sitting-pivot wheelchair transfers.We recommend a minimum of five transfer trials to obtain a reliable measure of transfer technique for future studies.

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.

Movement strategies during car transfers in individuals with tetraplegia: a preliminary study

STUDY DESIGN

Three-dimensional kinematic analysis of car transfer (CT) movement in four adult males with C6 tetraplegia.

OBJECTIVES

The aim of the present study was to assess the normal transfer technique movement from a wheelchair to a car (that is, CT) in subjects with tetraplegia. A better understanding of CT movement is invaluable knowledge for spinal cord injury rehabilitation. This type of knowledge will improve rehabilitation programs so that patients with tetraplegia will have greater societal participation.

SETTING

School of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan.

METHODS

Four adult males with C6 tetraplegia, an impairment grade of A according to the American Spinal Injury Association guidelines, took part in the study. The subjects used their own wheelchair and car in our assessments of their CT movement technique. Movements were assessed using a three-dimensional video analysis system with six digital video cameras. CT data, which included lateral displacement of the head and buttocks, and angular displacement of neck flexion and trunk forward inclination, were collected and correlation coefficients were calculated.

RESULTS

All four subjects demonstrated negative correlations in lateral displacements greater than 0.70. As for correlation coefficients of angular displacement, two subjects demonstrated negative correlations (r = -0.98 and r = -0.77) and one subject demonstrated a positive correlation (r = 0.75). The neck flexion and trunk forward inclination strategy was different among the four subjects.

CONCLUSIONS

Each subject with C6 tetraplegia demonstrated different strategies during CT movement.

Upper limb kinetic analysis of three sitting pivot wheelchair transfer techniques

BACKGROUND

The objective of this study was to investigate differences in shoulder, elbow and hand kinetics while performing three different SPTs that varied in terms of hand and trunk positioning.

METHODS

Fourteen unimpaired individuals (8 male and 6 female) performed three variations of sitting pivot transfers in a random order from a wheelchair to a level tub bench. Two transfers involved a forward flexed trunk (head-hips technique) and the third with the trunk remaining upright. The two transfers involving a head hips technique were performed with two different leading hand initial positions. Motion analysis equipment recorded upper body movements and force sensors recorded hand reaction forces. Shoulder and elbow joint and hand kinetics were computed for the lift phase of the transfer.

FINDINGS

Transferring using either of the head hips techniques compared to the trunk upright style of transferring resulted in reduced superior forces at the shoulder (P<0.002), elbow (P<0.004) and hand (P<0.013). There was a significant increase in the medial forces in the leading elbow (P=0.049) for both head hip transfers and the trailing hand for the head hip technique with the arm further away from the body (P<0.028). The head hip techniques resulted in higher shoulder external rotation, flexion and extension moments compared to the trunk upright technique (P<0.021).

INTERPRETATION

Varying the hand placement and trunk positioning during transfers changes the load distribution across all upper limb joints. The results of this study may be useful for determining a technique that helps preserve upper limb function overtime.

Load on the shoulder complex during wheelchair propulsion and weight relief lifting

BACKGROUND

This study focuses on the relationship between overuse in association with wheelchair activities of daily living and risks for osteoarthrosis in the acromioclavicular and sternoclavicular joints. The aim is to quantify the joint moments and joint reaction forces in all three joints of the shoulder complex during wheelchair-related activities of daily living.

METHODS

A convenience sample of 17 subjects performed two tasks (wheelchair propulsion and weight relief lifting). Three-dimensional kinematics and kinetics were measured and position and force data were used as input for a musculoskeletal model of the arm and shoulder. Output variables of the model were the moments and the joint reaction forces on the sternoclavicular, acromioclavicular and glenohumeral joints.

FINDINGS

Moments on the sternoclavicular joint were higher than on the acromioclavicular and glenohumeral joint, but the joint reaction forces on the sternoclavicular and acromioclavicular joints were only one third of those on the glenohumeral joint (peak forces around 96N compared to 315N for wheelchair propulsion and around 330N compared to 1288N for weight relief lifting).

INTERPRETATION

Based on the results found in this study, net joint moments are likely a better measure to describe the load on the acromioclavicular and sternoclavicular joints due to the passive stabilization. Prospective studies on wheelchair overuse injuries should also look at the acromioclavicular and sternoclavicular joints since the load of wheelchair tasks might be a risk factor for osteoarthrosis in these joints.

An expert review of the scientific literature on independent wheelchair transfers

PURPOSE

The purpose of this study was to perform a literature review and seek expert opinion on the relevance and strength of the evidence concerning setup and transfer performance.

METHODS

Scientific literature databases were searched until June 2009 using 43 keywords resulting in 339 articles. These were internally reviewed and narrowed to 41 articles which were formally assessed by 13 external experts. Articles that 80% or more of the reviewers scored as moderately or highly relevant were included in the final results.

RESULTS

Nineteen articles met the relevancy criteria. The aspects of setup that experts felt were addressed to some degree included vertical transfer distance, transferring across a gap and position of the mobility device relative to target destination. None of the 19 articles were scored as having strong to very strong resulting evidence.

CONCLUSIONS

There is a consensus among studies that transferring to a higher surface implies greater exertion of the upper limb. However, there is no evidence concerning how high or low, how close, and how much space is needed next to the target surface so it can be accessible by a majority of wheelchair users.