Wheelchair-dependent Individuals Research Articles

Effect of Tilt-in-Space and Reclining Angles of Wheelchairs on Normal Force and Shear Force in the Gluteal Region.

Healthcare workers need to educate patients regarding proper sitting positions to prevent pressure injuries in the elderly and disabled. The purpose of this study was to investigate the differences in normal and shear force in the gluteal region using the combination of tilt-in-space and reclining functions of wheelchairs. Twelve healthy subjects were recruited. Protocols for 15 wheelchair tilt-in-space and reclining angles, including three reclining angles (0°, 10°, and 20°) and five tilt-in-space (0°, 5°, 10°, 15°, and 20°), were randomly assigned. To measure the amount of normal and shear force applied to the gluteal region while sitting on a wheelchair, a force plate was placed on the seat to measure the seat reaction force. For statistical analysis, a two-factor analysis of variance, with tilt-in-space and reclining, was performed for each normal and shear force. The normal force showed a significant decrease with increased reclining angle. For the shear force combined with sagittal and lateral components, the 10° tilt-in-space showed a significant decrease compared to other conditions. The combination of 20° reclining and 10° tilt-in-space angles may decrease both normal and shear force in the gluteal region while sitting. These findings may help wheelchair-dependent individuals avoid pressure injuries.

Sociodemographic characteristics associated with physical activity barrier perception among manual wheelchair users

BackgroundIndividuals with disabilities are sub-optimally active and at increased risk for chronic diseases. Limited knowledge exists about how differences among wheelchair-dependent individuals may affect their perception of physical activity barriers. ObjectiveWe examined whether the perception of physical activity barriers are associated with wheelchair user sociodemographic characteristics. MethodsDanish manual wheelchair users (MWCUs) (N = 181; 52.5% females, mean ± SD: age 48 ± 14 yrs) completed the ‘Barriers to Physical Activity Questionnaire for People with Mobility Impairments’ (BPAQ-MI) online. The BPAQ-MI queries physical activity barriers in four domains (intrapersonal, interpersonal, organizational, and community) and eight subdomains. Participant characteristics evaluated as potentially associated with physical activity barriers included age, sex, years in chair, body mass index (BMI), spinal cord injury (SCI) (if any), education, employment, and resident city size. Simple linear regression (step 1) and multiple regression models (step 2) were created to assess associations between MWCU characteristics and barriers. ResultsMultiple regression models revealed that MWCUs who were obese, who did not complete high school, or were unemployed rated physical activity barriers higher across several subdomains (all r2≤0.226, p<0.05). Resident city size was associated with safety subdomain barrier impact (r2=0.039, p<0.05). Sex, age, years in chair and SCI were not associated with any barrier domains (all p ≥ 0.064). ConclusionsOur results provide new evidence that MWCUs with BMI ≥30; who are not employed; or who only have completed high school, may need special consideration and resources to overcome distinct physical activity barriers. Behavioral strategies and interventions focusing on reducing physical activity barriers should be tailored to the individuals above.

Validity of consumer-grade activity monitor to identify manual wheelchair propulsion in standardized activities of daily living.

BackgroundHypoactive lifestyle contributes to the development of secondary complications and lower quality of life in wheelchair users. There is a need for objective and user-friendly physical activity monitors for wheelchair-dependent individuals in order to increase physical activity through self-monitoring, goal setting, and feedback provision.ObjectiveTo determine the validity of Activ8 Activity Monitors to 1) distinguish two classes of activities: independent wheelchair propulsion from other non-propulsive wheelchair-related activities 2) distinguish five wheelchair-related classes of activities differing by the movement intensity level: sitting in a wheelchair (hands may be moving but wheelchair remains stationary), maneuvering, and normal, high speed or assisted wheelchair propulsion.MethodsSixteen able-bodied individuals performed sixteen various standardized 60s-activities of daily living. Each participant was equipped with a set of two Activ8 Professional Activity Monitors, one at the right forearm and one at the right wheel. Task classification by the Active8 Monitors was validated using video recordings. For the overall agreement, sensitivity and positive predictive value, outcomes above 90% are considered excellent, between 70 and 90% good, and below 70% unsatisfactory.ResultsDivision in two classes resulted in overall agreement of 82.1%, sensitivity of 77.7% and positive predictive value of 78.2%. 84.5% of total duration of all tasks was classified identically by Activ8 and based on the video material. Division in five classes resulted in overall agreement of 56.6%, sensitivity of 52.8% and positive predictive value of 51.9%. 59.8% of total duration of all tasks was classified identically by Activ8 and based on the video material.ConclusionsActiv8 system proved to be suitable for distinguishing between active wheelchair propulsion and other non-propulsive wheelchair-related activities. The ability of the current system and algorithms to distinguish five various wheelchair-related activities is unsatisfactory.

Impact of spine alignment on the rotator cuff in long-term wheelchair users

We investigated the impact of poor seated posture on the prevalence of rotator cuff tears (RCTs) among wheelchair-dependent individuals with long-standing paraplegia. The study included 319 patients. Lateral radiographs of the spine were collected from a database and analyzed to assess the global spinopelvic alignment (SPA). Magnetic resonance images of both shoulders were obtained to detect the presence of cuff tears. Patients were divided into 2 groups: Group RCT-I included all patients with cuff tears (right, left, or bilateral), whereas group RCT-II consisted exclusively of patients with bilateral cuff tears. We used the classification systems developed by Kendall et al and Roussouly et al to assess the sagittal spine alignment and SPA, respectively. Univariate and multivariate analyses were performed. To fit both models (groups RCT-I and RCT-II) to the data, the 4 spine curves according to Roussouly et al were subdivided into 2 groups: Group SPA-I included both type 1 and type 2, whereas group SPA-II included both type 3 and type 4. Magnetic resonance images showed a cuff tear in 192 patients (60.19%) (group RCT-I). Among those, 37 patients (11.60%) had tears in both shoulders (group RCT-II). In group RCT-I, 70.31% of the patients had a kyphotic-lordotic posture. The kyphotic-lordotic posture, a longer duration, and a more rostral neurologic level of injury were highly associated with cuff tear prevalence. In group RCT-II, the multivariate analysis showed that only the duration of spinal cord injury was significantly associated with RCTs. Thoracic hyperkyphosis was associated with a markedly high rate of RCTs. The data from this study may provide support for developing preventive strategies.

Prevalence of upper extremity pain in a population of people with paraplegia.

Cross-sectional study. To determine the prevalence, patterns, and predictors of musculoskeletal pain in the upper extremity joints among wheelchair-dependent individuals with post-traumatic paraplegia. Secondarily, to document most common reported causes of upper extremity pain. Centre for Orthopaedics, Trauma Surgery and Spinal Cord Injury, Germany. The study was done by means of a structured questionnaire, which was mailed to the individuals who had been treated between 1990 and 2007 for newly sustained or pre-existing, accident-related paraplegia (n = 670). The questionnaire was designed mainly to obtain the information regarding shoulder, elbow, and wrist pain. Additional data included participant demographics, mechanism, level and completeness of injury as well as wheelchair dependence and time since injury. The Frankel classification system was used to define the completeness of injury. Four hundred and fifty-one (67%) questionnaires were included. Pain was reported by approximately 81% of the participants. Of this sample, 61% had shoulder pain, 33% had elbow pain, and 43% had wrist pain, 19% had shoulder, elbow, and wrist pain, 27% had shoulder and elbow pain, 34% had shoulder and wrist pain, 21% had elbow and wrist pain. The main diagnoses were rotator cuff tears for individuals with shoulder pain, epicondylitis for those with elbow pain, and carpal tunnel syndrome for those with wrist pain. The development of shoulder/elbow and wrist pain correlated with age and time since injury. Age and the length of time since injury correlated with a higher rate of shoulder, elbow, and wrist pain. The completeness of injury, neurological level, and gender were correlated with shoulder, elbow, and wrist pain, respectively.

Effects of anterior weight-shifting methods on sitting balance in wheelchair-dependent patients with spinal cord injury.

[Purpose] This study aimed to compare changes in the center of pressure between healthy subjects and patients with spinal cord injury and to provide basic information to these patients for improving their sitting balance. [Subjects and Methods] A total of 12 healthy subjects without histories of neurological or psychiatric disorders and 12 patients with spinal cord injuries were recruited. In all subjects, a change in the center of pressure during the performance of the modified functional reach test was measured using a Force Sensing Array system while the subjects were seated in a wheelchair. In the spinal cord injury group, the change in the center of pressure was highest when subjects reached forward while holding a gym ball. [Results] In the spinal cord injury group, the change in the center of pressure was highest when subjects reached forward while holding a gym ball. A significant correlation between forward reaching of the upper limbs with shoulders at 90° flexion and a change in the center of pressure was found. [Conclusion] Our findings suggest that the combination of functional reaching and the change in the center of pressure assessment is novel enough to be attempted to achieve sitting balance control in patients with spinal cord injury. The findings can provide clinical interventions that contribute to the improvement in the balance ability of wheelchair-dependent individuals.

Description of Urological Surveillance and Urologic Ultrasonography Outcomes in a Cohort of Individuals with Long-Term Spinal Cord Injury.

Background: Individuals with spinal cord injury (SCI) have an increased risk of developing urological complications. Therefore, long-term routine urological surveillance is recommended. Objective: To describe urological surveillance in individuals with long-term SCI and to determine factors associated with urologic ultrasonography (UU) outcome. Methods: Wheelchair-dependent individuals with an SCI for 10 years or more were included. A medical assessment was done in 8 participating rehabilitation centers. The International Lower Urinary Tract Function Basic SCI Data Set was used to assess bladder-emptying methods and previous surgical procedures on the urinary tract. We studied urological surveillance: whether participants had routine urological checkups (including UU) and when latest urodynamic study was performed. Latest UU (performed <1 year ago) was retrieved or, when lacking, UU was performed as part of our study. Results: Median time since injury (TSI) was 22.0 years. Overall, 39% of the 282 participants did not have routine urological checkups and 33% never had a urodynamic study performed. UU data (N = 243) revealed dilatation of the upper urinary tract (UUT) in 4.5% of the participants and urinary stones in 5.7%. Abnormal UU outcome was associated with increasing TSI, nontraumatic SCI, and previous surgical bladder or UUT stone removal. UU outcome was not associated with routine urological checkups or type of bladder-emptying method. Conclusions: Over one-third of Dutch individuals with long-term SCI did not receive routine urological surveillance. UU outcome was not associated with routine urological checkups or type of bladder-emptying method. Further research on the indication and frequency of urological surveillance is recommended.

Arthroscopic rotator cuff repair in the weight-bearing shoulder

In wheelchair-dependent individuals, pain often develops because of rotator cuff tendon failure and/or osteoarthritis of the glenohumeral joint. The purposes of this study were to investigate (1) specific rotator cuff tear patterns, (2) structural healing, and (3) clinical outcomes after arthroscopic rotator cuff repair in a cohort of wheelchair-dependent patients. Forty-six shoulders with a mean follow-up of 46 months (range, 24-82 months; SD, 13 months) from a consecutive series of 61 shoulders in 56 patients (46 men and 10 women) undergoing arthroscopic rotator cuff repair were available for analysis. Clinical outcome analysis was performed using the Constant-Murley score, the Subjective Shoulder Value, and the American Shoulder and Elbow Surgeons score. The integrity of the repair was analyzed by ultrasound. Of the shoulders, 87% had supraspinatus involvement, 70% had subscapularis involvement, and 57% had an anterosuperior lesion involving both the supraspinatus and subscapularis. Despite an overall structural failure rate of 33%, the patients showed improvements in the Constant-Murley score from 50 points (range, 22-86 points; SD, 16 points) preoperatively to 80 points (range, 40-98 points; SD, 12 points) postoperatively and in the American Shoulder and Elbow Surgeons score from 56 points (range, 20-92 points; SD, 20 points) preoperatively to 92 points (range, 53-100 points; SD, 10 points) postoperatively, with a mean postoperative Subjective Shoulder Value of 84% (range, 25%-100%; SD, 17%). Failure of the rotator cuff in weight-bearing shoulders occurs primarily anterosuperiorly. Arthroscopic rotator cuff repair leads to a structural failure rate of 33% but satisfactory functional results with high patient satisfaction at midterm follow-up.

Self-reported physical activity and risk markers for cardiovascular disease after spinal cord injury.

To examine whether self-reported physical activity of a moderate/vigorous intensity influences risk markers for cardiovascular disease in persons with paraplegia due to spinal cord injury. Descriptive, cross-sectional study. A total of 134 wheelchair-dependent individuals (103 men, 31 women) with chronic (≥ 1 year) post-traumatic spinal cord injury with paraplegia. Cardiovascular disease markers (hypertension, blood glucose and a blood lipid panel) were analysed and related to physical activity. One out of 5 persons reported undertaking physical activity ≥ 30 min/day. Persons who were physically active ≥ 30 min/day were significantly younger than inactive persons. Systolic and diastolic blood pressures were lower in the physically active group. When adjusting for age, the association between systolic blood pressure and physical activity disappeared. Physical activity ≥ 30 min/day had a tendency to positively influence body mass index and low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio. Men had significantly higher systolic and diastolic blood pressures than women, lower high-density lipoprotein cholesterol, higher low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio and higher triglycerides. No other significant differences between men and women were found. Self-reported physical activity ≥ 30 min/day in persons with spinal cord injury positively influenced diastolic blood pressure. No other reductions in cardiovascular disease risk markers were seen after controlling for age. These results indicate a positive effect of physical activity, but it cannot be concluded that recommendations about physical activity in cardiovascular disease prevention for the general population apply to wheelchair-dependent persons with spinal cord injury.

Effects of an exercise programme on musculoskeletal and neuropathic pain after spinal cord injury—results from a seated double-poling ergometer study

To assess pain relieving effects of an intensive exercise programme on a seated double-poling ergometer in individuals with spinal cord injury (SCI). Stockholm, Sweden. A total of 13 wheelchair-dependent individuals with a thoracic or lumbar SCI were recruited to a 10-week training period (three times weekly) assessing the effects of regular training on upper-body strength, aerobic and mechanical power, and crossover effects on functional performance, as well as cardiovascular risk factors. Eight of the participants reported pain and were included in this exploratory pain protocol and assessed using the International SCI Basic Pain Data set, the Wheelchair Users' Shoulder Pain Index and International SCI Quality of Life Basic Data set. For those with neuropathic pain, median pain intensity ratings decreased from 5 on a 0-10 numerical rating scale at base-line to 3 at the end of study, and four of seven participants reported an improvement on the Patient Global Impression of Change scale. For those with musculoskeletal pain (n = 5), median pain intensity ratings improved from 4 at baseline to 0 at the end of study. All but one rated no musculoskeletal pain at all at the end of study and number of days with pain per week decreased from 5.5 to 0.7. None of the participants developed pain, because of overuse during the training period and few reported unwanted side effects. Considering its promising effects and safety, an intensive exercise programme can be tried for treating musculoskeletal pain and also neuropathic pain following SCI.

Electromyogram-Triggered Functional Electrical Stimulation-Assisted Walking After Partial Paralysis

Objective: Functional Electrical Stimulation (FES) triggered by manual switch provides brace-free ambulation to wheelchair dependent individuals with spinal cord injuries. An electromyogram (EMG)-based trigger can enhance the coordination between FES-assisted and volitional actions. This study evaluated the gait speed modulation and coordination of the actions of the EMG-triggered FES with the volitional movements during stand-to-walk transition after incomplete spinal cord injury. Methods: two incomplete spinal cord injured (iSCI) subjects (iSCI1: 24years, C7 motor &amp; C6 sensory; iSCI2: 34years, T1 motor &amp; C5 sensory) volunteered for this study. Four able-bodied volunteers provided the normative gait data. The Vicon WorkstationTM (Vicon Peak, USA) software acquired lower-body kinematics data using a seven camera motion capture system during stand-to-walk transition. The FES-assisted swing-phase in iSCI subjects was triggered with three command interfaces—manually triggered with a switch, triggered with EMG-based GED, triggered automatically at a user-selected rate. Results and Discussion: The Euclidean distance from origin of the perturbations of 18 joint angles and 18 joint velocities during stand-to-walk transition converged towards zero. It was found from the Mahalanobis distances between each pair of group means that the EMG-triggered FES-assisted iSCI gait was closest to the able-bodied normative gait clusters.

Five additional mobility and locomotor items to improve responsiveness of the FIM in wheelchair-dependent individuals with spinal cord injury

Repeated-measures design. To assess the validity and responsiveness of five additional mobility and locomotor (5-AML) items when used in conjunction with the Functional Independence Measure (FIM) for assessing the mobility and locomotor function of individuals with spinal cord injury (SCI). Specialised acute spinal and rehabilitation units in Sydney, Australia. A previously published scale comprising five key mobility and locomotor skills was further refined. The five items included a bed mobility and vertical (floor-to-chair) transfer item and three wheelchair propulsion items (pushing 200 m over flat ground, pushing up a ramp and negotiating a kerb). A total of 43 eligible patients with SCI (ASIA A-C impairment) admitted consecutively to two acute SCI units in Sydney between 1999 and 2002 were recruited, with four being lost to follow-up. Locomotor and mobility outcomes were measured at regular intervals for up to 6 months with the FIM and the 5-AML. Construct validity of the 5-AML was assessed by testing ability of items to discriminate between different impairment groups (tetraplegia and paraplegia). Item responsiveness was assessed by analysing ability to detect changes in mobility and locomotor function over time. Factor analysis techniques were used to test the hypothesis that the 5-AML, when used in conjunction with the FIM, provides a more sensitive measure of mobility and locomotor function than the FIM alone. The 5-AML items were shown to be valid and responsive, measuring aspects of 'real world' mobility and locomotor function not reflected by the FIM. The bed mobility item was highly responsive to change over time for the tetraplegic group, but quickly reached a ceiling in the paraplegic group. The vertical (floor-to-chair) transfer item showed greater responsiveness over time and less ceiling effect for the paraplegic group than any of the FIM locomotor or mobility items. The three wheelchair propulsion items better discriminated between people with tetraplegia and paraplegia, and were more sensitive to changes in locomotor ability over the 6-month period than FIM locomotor items. Results of a preliminary factor analysis indicated that the 5-AML items measure different aspects of mobility and locomotor function than the FIM. The 5-AML items, when used in conjunction with the FIM, provides better delineation of function between people with tetraplegia and paraplegia and provides a more responsive measure of change in function over time than the FIM alone.

Energy expenditure in wheelchair racing and handbiking - a basis for prevention of cardiovascular diseases in those with disabilities.

Handbiking and wheelchair racing have gained increased popularity in Germany. This is important because of the inability of wheelchair-dependent people to maintain cardiovascular health and fitness through daily activities. The purpose of this study was to evaluate the energy expenditure (EE; kcal/h) of wheelchair-dependent individuals. Ten wheelchair racers (WR) and 17 handbikers (HB) completed a basal metabolism evaluation, an incremental exercise test until exhaustion and an endurance test. Oxygen uptake and carbon dioxide production ([V(. -)]O(2), [V(. -)]CO(2); ml/min), arterialized capillary blood lactate concentration (LA; mmol/l) and heart rate (HR; bpm) were recorded during each test. EE was calculated by indirect calorimetry. In the endurance test [V(. -)]O(2), [V(. -)]CO(2), LA, HR and EE at an intensity corresponding to 2 mmol/l lactate were: HB: 1332+/-368 ml/min, 1178+/-303 ml/min, 2.23+/-0.85 mmol/l, 116.8+/-19.1 bpm, 389.6+/-105.4 kcal/h; WR:1175+/-285 ml/min, 1145+/-258 ml/min, 2.65+/-0.36 mmol/l, 142.5+/-28.0 bpm, 341.7+/-84.0 kcal/h. At an intensity corresponding to 4 mmol/l lactate the values were: HB: 1792+/-408 ml/min, 1666+/-326 ml/min, 4.27+/-1.40 mmol/l 146.1+/-22.8 bpm, 530.1+/- 115.4 kcal/h; WR: 1505+/-210 ml/min, 1427+/-188 ml/min, 3.31+/-1.0 mmol/l, 165.3+/-22.7 bpm, 445.5+/-70.8 kcal/h. The results show that EE of HB and WR is high enough to maintain fitness and probably to help to prevent cardiovascular diseases even at a moderate intensity.

GROSS MECHANICAL EFFICIENCY OF HAND RIM WHEELCHAIR PROPULSION DURING SCI REHABILITATION

During rehabilitation of wheelchair-dependent individuals with a spinal cord injury (SCI), task proficiency is expected to improve as a consequence of learning and training. During submaximal wheelchair propulsion, gross mechanical efficiency (ME) is viewed as an adequate indicator of overall task proficiency. Currently, no data exist in this respect. PURPOSE To describe and analyze changes in ME during SCI rehabilitation. METHODS In the context of a Dutch multi-center prospective cohort study, 23 subjects with SCI (3 subjects with tetraplegia, 5 females) performed three subsequent submaximal wheelchair exercise tests on a motor driven treadmill: at the start of active rehabilitation (t1), 3 months later (t2) and at the end of clinical rehabilitation (t3). In each test, ME was evaluated for the final minute of each of two 3-min stages of submaximal wheelchair exercise in a standardized hand rim wheelchair on a motor driven treadmill. Changes over time were evaluated with an ANOVA for repeated measures (main factors (levels): time((t1,2,3), (3)); exercise stage (2); level of significance: p < 0.05). RESULTS Mean power output was 9.2±4.3W and 13.5±5.2W for the subsequent two stages at t1, and showed a small but significant increase over time (10.0±4.2W and 14.8±4.9W for the respective two stages at t3). Oxygen uptake showed a slight non-significant downward trend over time. Mean ME significantly increased for the first stage from 5±2% at t1 to 5.6±2.1% at t3 and from 7.1±2.5% at t1 to 7.8±2.6% at t3 for the second exercise stage (p < 0.01). Mean heart rate and ventilation significantly dropped over time at both levels of power output (p < 0.01). CONCLUSIONS Results show a steady increase in wheeling proficiency over time, indicating effects of learning and training during the course of rehabilitation. At a later stage of this multi-center study the role of lesion level, completeness of the lesion, age and gender on ME will be evaluated. Supported by ZON-MW Rehabilitation grant 1435.0003

Alternative modes of manual wheelchair ambulation: an overview.

An estimated 90% of all wheelchairs are hand-rim propelled, a physically straining form of ambulation that can lead to repetitive strain injuries in the arms and, eventually, to secondary impairments and disability. Further disability in wheelchair-dependent individuals can lead to a sedentary lifestyle and thereby create a greater risk for cardiovascular problems. Studies on lever-propelled and crank-propelled wheelchairs have shown that these propulsion mechanisms are less straining and more efficient than hand-rim-propelled wheelchairs. This article reviews these studies and substantiates that the frequent use of these alternative propulsion mechanisms may help prevent some of the secondary impairments that are seen among today's wheelchair-user population.

An assessment of wrist splint and glove use on wheeling kinematics

Objective. The purpose of this investigation was to assess whether glove and/or splint use could effectively reduce hyperextension at the wrist during wheelchair propulsion, thus potentially reducing the conditions predisposing to median nerve dysfunction, and to evaluate the overall effects of these interventions on wheeling mechanics. Design. This investigation used a randomized experimental design. Background. The upper extremities are used for weight bearing and propulsion by individuals who are wheelchair dependent. High intracarpal pressures created by hyperextension of the wrist and repetitive high force stresses of the hands against the wheel are suggested causes of median nerve dysfunction. Methods. The wheeling performances of 13 subjects were recorded using two SVHS videocameras under four different glove/splint conditions. Each subject was analysed on two wheeling cycles under all four conditions. Wrist and elbow angles, joint range of motions and wheeling speed were determined. Data were analysed using a one-way analysis of variance ( anova), followed by Scheffé post-hoc comparisons at the 0.05 level of significance. Results. The splint and the glove/splint combination significantly reduced wrist extension during wheeling, but did not alter elbow motion or maximal wheeling speed. Conclusions. Hand and wrist protection in the form of a splint or glove/splint combination can reduce hyperextension of the wrist, and therefore may be of functional value for wheelchair users. This form of protection may therefore be useful in various orthopedic conditions of the wrist or hand commonly seen in wheelchair-dependent individuals without seriously interfering with wheeling quality.

Ramp length/grade prescriptions for wheelchair dependent individuals

The aim of this work was to provide well defined criteria for ramp construction for wheelchair dependent individuals (WDI). Force capability was measured in a large sample (140) of WDI, who presented different levels of motor impairment. Levels of impairment were established on the basis of the answers given in a questionnaire regarding the degree of self sufficiency at home as well as outside the home and active participation in sports events. Taking into account those WDI who exhibited at least a minimal level of self-sufficiency, the following prescriptions are indicated. For a 1 metre ramp length, allowable maximal incline 15%; up to 3 metre ramp length, maximal incline 10%. The reliability of such prescriptions was confirmed by having a test ramp traversed by 43 WDI. These values are suggested as confidence limits when faced with public building accommodations. Special prescriptions could be adopted for selected populations of WDI.

Prediction of ramp traversability for wheelchair dependent individuals

The purpose of this research was to obtain a single objective criterion that would constitute a reliable prediction of length and grade limits for ramps that can be traversed by any special category of wheelchair dependent individuals (WDI). The maximal voluntary force (MVC) is the main limiting factor of the performance of WDI, thus the force required to traverse a ramp has been established by means of a simple mechanical model. The real time course of force application during ascent was experimentally obtained. Then, a simplified law of force application was introduced in a computer simulation program of kinetics and kinematics of ascent. Inputs to the model were also the mass of the subject plus wheelchair, the initial velocity of the chair, and the ramp length. The output of the program was the force requirement for any given length/grade. When capsizing conditions were encountered the simulation ended. We tested the results thus obtained having some selected WDI successfully traversing ramps with the predicted length/grade specifications.

Effect of seat angle and lumbar support on seated buttock pressure.

The purpose of this study was to compare the effects of a lumbar support at two seat angles (0 degrees and 10 degrees of posterior tilt) on the area of highest buttock pressure. Twenty able-bodied subjects were seated on a pressure-sensing transducer incorporated into an adjustable chair (ischiobarograph). A video camera on the underside of the transducer detected changes in light levels in direct relation to pressure application. The camera output was processed by a microcomputer system that converted the signal into nine colors, each representing a distinct pressure interval in the range of 0 to more than 500 mm Hg. The microcomputer determined the area of each pressure interval before and after a 10-degree posterior tilt of the seat and lumbar support placement. The results demonstrated high test-retest reliability for each position (r = .95). A significant decrease in the six highest pressure intervals occurred when the lumbar support was used in both the upright and reclined positions (p less than .05). The results of this study have implications for wheelchair-dependent individuals.