Craniofacial injuries related to motorized scooter use: A rising epidemic.

OBJECTIVES: Over the last decade, there has been increased interest in utilizing motorized scooters for transportation. The limited regulation of this modernized vehicle raises numerous safety concerns. This analysis examines a national database to describe the yearly incidence of craniofacial injuries and patterns of injury related to motorized scooter use. METHODS: The Consumer Product Safety Commission's National Electronic Injury Surveillance system was queried for craniofacial injuries associated with motorized scooter use. Patient demographics, injury type, anatomic location, injury pattern, and helmet status were extracted for analysis. RESULTS: From 2008 to 2017, there were 990 recorded events for craniofacial injuries secondary to motorized scooters extrapolating to an estimated 32,001 emergency department (ED) visits. The annual incidence was noted to triple over that 10-year period. The majority of patients were male (62.1%) and the common age groups at presentation were young children 6-12 years old (33.3%), adolescents 13-18 years old (16.1%) and young adults 19-40 years old (18.0%). The most common injury pattern was a closed head injury (36.1%) followed by lacerations (20.5%). Facial fractures were only present in 5.2% of cases. In cases in which helmet use was recorded, 66% of the patients were not helmeted. CONCLUSION: The incidence of motorized scooter related craniofacial trauma is rising, resulting in thousands of ED visits annually. Many patients are experiencing morbid traumatic injuries and may not be wearing appropriate protective equipment. This study highlights the importance of public awareness and policy to improve safety and primarily prevent craniofacial trauma.

Effects of hybrid cycling versus handcycling on wheelchair-specific fitness and physical activity in people with long-term spinal cord injury: a 16-week randomized controlled trial.

STUDY DESIGN: This is an open randomized controlled trial. OBJECTIVE: The objective of this study was to investigate the effects of a 16-week hybrid cycle versus handcycle exercise program on fitness and physical activity in inactive people with long-term spinal cord injury (SCI). SETTING: The study was conducted in two rehabilitation centers with a specialized SCI unit. METHODS: Twenty individuals (SCI⩾8 years) were randomly assigned to a hybrid cycle (voluntary arm exercise combined with functional electrical stimulation (FES)-induced leg exercise) or a handcycle group. During 16 weeks, both groups trained twice a week for 30 min at 65-75% heart rate reserve. Outcome measures obtained before, during and after the program were fitness (peak power output, peak oxygen consumption), submaximal VO2 and heart rate (HR), resting HR, wheelchair skill performance time score) and physical activity (distance travelled in wheelchair and Physical Activity Scale for Individuals with Physical Disabilities (PASIPD) score). Changes were examined using a two-factor mixed-measures analysis of variance. RESULTS: For all fitness parameters, except for submaximal VO2, no interaction effects were found. The hybrid cycle group showed a decrease in VO2 over time in contrast to the handcycle group (P=0.045). An overall reduction in HRrest (5±2 b.p.m.; P=0.03) and overall increase in PASIPD score (6.5±2.1; P=0.002) were found after 16 weeks of training. No overall training effects were found for the other fitness and activity outcome measures. CONCLUSION: In the current study, hybrid cycling and handcycling showed similar effects on fitness and physical activity, indicating that there seem to be no additional benefits of the FES-induced leg exercise over handcycle training alone.

Physical medicine devices; reclassification of stair-climbing wheelchairs. Final order.

The Food and Drug Administration (FDA) is issuing a final order to reclassify stair-climbing wheelchairs, a class III device, into class II (special controls) based on new information and subject to premarket notification, and further clarify the identification.

Factors associated with provision of wheelchairs in older adults.

The objectives of this study were: to identify the factors that are associated with prescription of wheeled mobility devices for older adults, and to determine the effect that living setting has on the types of devices that older adults receive. Retrospective medical chart review at the Center for Assistive Technology on 337 older individuals. These individuals were aged >60 years, and each of them received a new wheeled mobility device from the center during 2007 or 2008. Data were analyzed in three tiers: tier 1 (manual versus powered mobility devices); tier 2 (motorized scooters versus power wheelchairs); and tier 3 (customized versus standard power wheelchairs). For tier 1, the factor associated with higher odds for receipt of manual wheelchairs versus powered were: cognitive limitations (OR = .03). For tier 2, diagnosis of cardio-vascular and pulmonary conditions were associated with prescription of motorized scooters (OR = 3.9). For tier 3, neurological conditions (OR = 3.1), male gender (OR = .37), institutional living (OR = .23), and lower age (OR = .96) were associated with receipt of customized power wheelchairs. This study objectively describes factors associated with prescription of wheeled mobility for older adults. This information can aid in development of guidelines and improving standards of practice for prescription of wheelchairs for older adults.

Mini-review: Robotic wheelchair taxonomy and readiness.

Robotic wheelchair research and development is a growing sector. This article introduces a robotic wheelchair taxonomy, and a readiness model supported by a mini-review. The taxonomy is constructed by power wheelchair and, mobile robot standards, the ICF and, PHAATE models. The mini-review of 2797 articles spanning 7 databases produced 205 articles and 4 review articles that matched inclusion/exclusion criteria. The review and analysis illuminate how innovations in robotic wheelchair research progressed and have been slow to translate into the marketplace.

The differences in self-esteem, function, and participation between adults with low cervical motor tetraplegia who use power or manual wheelchairs.

OBJECTIVE: To explore the differences between manual and power wheelchair users in terms of self-esteem, function, and participation in persons with a similar motor level of spinal cord injury (SCI). DESIGN: Descriptive cross-sectional study with a single data collection. SETTING: General community. PARTICIPANTS: Participants (N=30) were a convenience sample of adults with self-reported C6 and C7 tetraplegia caused by SCI who are 1 or more years postinjury. Eighteen were manual chair users, and 12 were power chair users. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Rosenberg Self-Esteem Scale, Spinal Cord Independence Measure III (SCIM III) as a measure of function, and the Craig Handicap Assessment and Reporting Technique (CHART) as a measure of participation. RESULTS: There were no significant differences between manual and power chair users regarding age, time since injury, or length of initial rehabilitation stay. A significant difference was seen between wheelchair groups (F=2.677, P=.038). Multivariate analysis showed the differences to be in the SCIM III (F=11.088, P=.003) and the CHART subcategories Physical (F=7.402, P=.011), Mobility (F=12.894, P=.001), and Occupation (F=5.174, P=.031). CONCLUSIONS: Manual wheelchair users demonstrated better physical function, mobility, and had a higher employment rate than power wheelchair users based on the SCIM III and CHART in this sample of adults with C6 or C7 motor level tetraplegia.

Clinical features of electric powered indoor/outdoor wheelchair users with spinal cord injuries: A cross-sectional study.

This article aims to describe the characteristics of those with a primary diagnosis of spinal cord injury (SCI) attending a specialist wheelchair service providing electric powered indoor/outdoor chairs (EPIOCs). This cross-sectional study, with retrospective review of electronic and case note records, explores the complexities of additional clinical features associated with SCI and disability influencing prescription. Data were extracted under three themes; demographics, diagnostic/clinical information and wheelchair factors. There were 57 participants (35 men, 22 women) (mean age 53.51 ± 11.93, range 29-79 years) comprising 20 with paraplegia, 34 with tetraplegia and 3 with undocumented level. Paraplegics were significantly older than tetraplegics (p < 0.05). Thirty users had a complete SCI (mean age 49.87 ± 12.27 years) and 27 had another SCI lesion (mean age 57.56 ± 10.32 years). Those with a complete SCI were significantly younger than the rest (p < 0.02). Only 10 (9 tetraplegic) had SCI as the sole diagnosis. Twenty (15 tetraplegic) had one additional clinical feature, 14 had 2-3 (6 tetraplegic) and 13 (4 tetraplegic) had 4 or more. Ten users required specialised seating, 22 needed tilt-in-space EPIOCs while six required complex controls. The range and complexity of wheelchair and seating needs benefitted from a holistic assessment and prescription by a specialist multidisciplinary team.

Relationship between wheelchair skills scores and peak aerobic exercise capacity of manual wheelchair users with spinal cord injury: a cross-sectional study.

Purpose: Although both wheelchair skills and fitness are important and probably inter-related, the extent and nature of the relationship between them are not well understood. The objective of this study was to test the hypothesis that there are significant relationships between wheelchair skills scores and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Materials and methods: We studied 26 participants, recording Wheelchair Skills Test Questionnaire scores and peak power output from graded aerobic wheelchair exercise testing on a motorized treadmill.Results: The median Wheelchair Skills Test Questionnaire capacity, confidence, and performance scores were 83.3%, 81.5%, and 76.7% and the median peak power output was 58.2 W. On regression analysis, there were significant relationships between the total Wheelchair Skills Test Questionnaire capacity, confidence, and performance scores and peak power output (R2 0.270-0.709, odds ratios 1.043-1.150, p < 0.05).Conclusions: Significant relationships exist between the wheelchair skills capacity, confidence, and performance scores and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury. These findings suggest that both wheelchair skills training and exercise training may be useful during the rehabilitation of people with spinal cord injury.Implications for rehabilitationModerate positive relationships exist between wheelchair skills capacity and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Moderate positive relationships exist between wheelchair skills confidence and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Although further research is needed, these findings suggest that clinicians should address both wheelchair skills training and exercise training during the rehabilitation of people with spinal cord injury and not assume that either alone is sufficient.

Promote pressure ulcer healing in individuals with spinal cord injury using an individualized cyclic pressure-relief protocol.

OBJECTIVE: To evaluate whether an individualized cyclic pressure-relief protocol accelerates wound healing in wheelchair users with established pressure ulcers (PrUs). DESIGN: Randomized controlled study. SETTING: Spinal cord injury clinics. PARTICIPANTS: Forty-four subjects, aged 18-79 years, with a Stage II or Stage III PrU, were randomly assigned to the control (n = 22) or treatment (n = 22) groups. INTERVENTIONS: Subjects in the treatment group used wheelchairs equipped with an individually adjusted automated seat that provided cyclic pressure relief, and those in the control group used a standard wheelchair. All subjects sat in wheelchairs for a minimum of 4 hours per day for 30 days during their PrU treatment. MAIN OUTCOME MEASURES: Wound characteristics were assessed using the Pressure Ulcer Scale for Healing (PUSH) tool and wound dimensions recorded with digital photographs twice a week. Median healing time for a 30% healing relative to initial measurements, the percentage reduction in wound area, and the percentage improvement in PUSH score achieved at the end of the trial were compared between groups. RESULTS: At the end of 30 days, both groups demonstrated a general trend of healing. However, the treatment group was found to take significantly less time to achieve 30% healing for the wound measurement compared with the control group. The percentage improvement of the wound area and PUSH scores were greater in using cyclic seating (45.0 +/- 21.0, P < .003; 29.9 +/- 24. 6, P < .003) compared with standard seating (10.2 +/- 34.9, 5.8 +/- 9.2). CONCLUSIONS: The authors' findings show that cyclically relieving pressure in the area of a wound for seated individuals can greatly aid wound healing. The current study provides evidence that the individualized cyclic pressure-relief protocol helps promote pressure wound healing in a clinical setting. The authors concluded that the individualized cyclic pressure relief may have substantial benefits in accelerating the healing process in wheelchair users with existing PrUs, while maintaining the mobility of individuals with SCI during the PrU treatment.

RESNA position on the application of power wheelchairs for pediatric users.

This document, approved by the Rehabilitation Engineering & Assistive Technology Society of North America (RESNA) Board of Directors in March 2007, shares typical clinical applications and provides evidence from the literature supporting the use of power wheelchairs for children.

Towards the Development of a Learning-Based Intention Classification Framework for Pushrim-Activated Power-Assisted Wheelchairs.

There has been a growth in the design and use of power assist devices for manual wheelchairs (MWCs) to alleviate the physical load of MWC use. A pushrim-activated power-assisted wheel (PAPAW) is an example of a power assist device that replaces the conventional wheel of a MWC. Although the use of PAPAWs provides some benefits to MWC users, it can also cause difficulties in maneuvering the wheelchair. In this research, we examined the characteristics of wheelchair propulsion when using manual and powered wheels. We used the left and right wheels' angular velocity to calculate the linear and angular velocity of the wheelchair. Results of this analysis revealed that the powered wheel's controller is not optimally designed to reflect the intentions of a wheelchair user. To address some of the challenges with coordinating the pushes on PAPAWs, we proposed the design of a user-intention detection framework. We used the kinematic data of MWC experiments and tested six supervised learning algorithms to classify one of four movements: "not moving", "moving straight forward", "turning left", and "turning right". We found that all the classification algorithms determined the type of movement with high accuracy and low computation time. The proposed intention detection framework can be used in the design of learning-based controllers for PAPAWs that take into account the individualized characteristics of wheelchair users. Such a system may improve the experience of PAPAW users.

Reliability and normative values of the Wheelchair Propulsion Test: A preliminary investigation.

BACKGROUND: Normative data for the equivalent of gait speed via the Wheelchair Propulsion Test (WPT) do not exist for wheelchair users. OBJECTIVE: The purposes of the current study were to: 1) determine the reliability of the WPT, 2) propose and compare normative values for the WPT for young adult males and females utilizing three different propulsion techniques, and 3) compare how different wheelchair types affect performance on the WPT. METHODS: 50 young adults (25 of each sex) performed the WPT using three different propulsion techniques in three different types of wheelchairs. Participants were asked to propel a wheelchair over 10 m at a comfortable speed. Time and number of pushes were recorded for three trials for each propulsion technique in each type of wheelchair. RESULTS: All of the ICC(2,2) values were >0.83 for speed and number of pushes. Normative values for speed, number of pushes, push frequency and effectiveness categorized by propulsion technique, sex and wheelchair type were developed. CONCLUSIONS: Preliminary normative values have been established for young adults performing the WPT. This study highlights the need to maintain consistency of the wheelchair type and propulsion technique between trials in order for the WPT to be reliable.

Comparison of seating, powered characteristics and functions and costs of electrically powered wheelchairs in a general population of users.

PURPOSE: To profile and compare the seating and powered characteristics and functions of electrically powered wheelchairs (EPWs) in a general user population including equipment costs. METHOD: Case notes of adult EPW users of a regional NHS service were reviewed retrospectively. Seating equipment complexity and type were categorized using the Edinburgh classification. Powered characteristics and functions, including control device type, were recorded. RESULTS: 482 cases were included; 53.9% female; mean duration EPW use 8.1 years (SD 7.4); rear wheel drive 88.0%; hand joystick 94.8%. Seating complexity: low 73.2%, medium 18.0%, high 8.7%. Most prevalent diagnoses: multiple sclerosis (MS) 25.3%, cerebral palsy (CP) 18.7%, muscular dystrophy (8.5%). Compared to CP users, MS users were significantly older at first use, less experienced, more likely to have mid-wheel drive and less complex seating. Additional costs for muscular dystrophy and spinal cord injury users were 3-4 times stroke users. CONCLUSIONS: This is the first large study of a general EPW user population using a seating classification. Significant differences were found between diagnostic groups; nevertheless, there was also high diversity within each group. The differences in provision and the equipment costs across diagnostic groups can be used to improve service planning. Implications for Rehabilitation At a service planning level, knowledge of a population's diagnostic group and age distribution can be used to inform decisions about the number of required EPWs and equipment costs. At a user level, purchasing decisions about powered characteristics and functions of EPWs and specialised seating equipment need to be taken on a case by case basis because of the diversity of users' needs within diagnostic groups. The additional equipment costs for SCI and MD users are several times those of stroke users and add between 60 and 70% of the cost of basic provision.

Data-mining analysis of the provision of mobility devices in the United States with emphasis on complex rehab technology.

The objective of this study was to describe the provision of wheeled-mobility equipment from the perspective of a large equipment supplier in the United States. The records of clients who were prescribed a mobility device over a 6-month period were randomly sampled to product a dataset of 1,689 clients. Analysis was limited to descriptive statistics and measures of relationships. The majority of the clients were adults (72%) and female (58%) with 62% receiving a manual wheelchair. The majority of interventions (58%) included some contribution from the client or client's family. Overall, 86% of all prescribed wheelchairs were classified as complex rehab technology (CRT). About half (52%) of all interventions involved a therapist. Therapist involvement was 2.5 times more likely during CRT interventions compared to standard durable medical equipment (StdDME). The project provides a novel description of mobility-related equipment provision using a large retrospective dataset. The analysis demonstrates the utility of analyzing a large number of client interventions. The capabilities of such analyses have business, clinical, and policy implications. Combining the data available from suppliers with prospective collection of client-specific information, such as outcomes, would be a more powerful means to assess the provision of wheeled-mobility equipment.

Stroke pattern classification during manual wheelchair propulsion in the elderly using fuzzy clustering.

The purpose of this study was to analyse the kinematic pattern of elderly group during manual wheelchair propulsion. Fourteen elderly persons propelled manually in a wheelchair ergometer. A new objective method based on metrical and topological aspect of the contour of hand center of mass is proposed. A geometric mapping transforms the original time-hand trajectory to a normalized couple of features (R1 and R2). Fuzzy clustering was used to classify wheelchair propulsion pattern based on their features R1 and R2. Four classes were found in order to represent different propulsion pattern. Significant differences were found between classes for fraction of effective force and the biomechanical effectiveness. It was also found that classes are posture dependent and this can help in developing rehabilitation programmes for different groups of patients.

Comparison between a tilt-in-space wheelchair and a manual wheelchair equipped with a new rear anti-tip device from the perspective of the caregiver.

OBJECTIVE: To test the hypothesis that, in comparison with a commercially available tilt-in-space wheelchair, a lightweight manual wheelchair equipped with a new, rear anti-tip device (Arc-RAD) provides caregivers with improved wheelchair-handling performance, less exertion, and greater satisfaction. DESIGN: Within-participant comparisons. SETTING: Rehabilitation center. PARTICIPANTS: Able-bodied participants (n=19) simulating caregivers and simulating wheelchair users (n=7). INTERVENTION: Caregiver participants were trained (50-75 min) in wheelchair-handling skills. MAIN OUTCOME MEASURES: Each participant was tested in both wheelchairs, in random order. To evaluate wheelchair-handling skills, we used the total percentage score on the Wheelchair Skills Test (WST), version 3.2. For exertion, we used a visual analog scale (in percent). For satisfaction, we used the Quebec Users' Evaluation of Satisfaction with assistive Technology (QUEST; range of values, 8-40), version 2. RESULTS: Mean percentage WST scores +/- SD for the Arc-RAD and tilt-in-space wheelchairs were 95.9%+/-4.2%, and 91.9%+/-4.8%, respectively (P=.008). The mean perceived exertions during Arc-RAD and tilt-in-space wheelchair use were 26.1%+/-20.4% and 46.6%+/-23.2% (P=.003). The mean total QUEST satisfaction scores for the Arc-RAD and tilt-in-space wheelchairs were 35.1+/-3.8 and 28.4+/-4.7 (P=.002). CONCLUSIONS: In comparison with the larger and heavier tilt-in-space wheelchair, a lightweight manual wheelchair equipped with a new rear anti-tip design allows 4.4% better wheelchair-handling performance, 44% less exertion, and 23.6% greater wheelchair satisfaction.

Clinical features of children and adults with a muscular dystrophy using powered indoor/outdoor wheelchairs: disease features, comorbidities and complications of disability.

PURPOSE: To describe the clinical features of electric powered indoor/outdoor wheelchair users with a muscular dystrophy, likely to influence optimal prescription; reflecting features of muscular dystrophies, conditions secondary to disability, and comorbidities impacting on equipment provision. METHODS: Cross-sectional retrospective case note review of recipients of electric powered indoor/outdoor wheelchairs provided by a specialist regional wheelchair service. Data on demography, diagnostic/clinical, and wheelchair prescription were systematically extracted. RESULTS: Fifty-one men and 14 women, mean age 23.7 (range 10-67, s.d. 12.95) years, were studied. Forty had Duchenne muscular dystrophy, 22 had other forms of muscular dystrophy, and three were unclassified. Twenty-seven were aged under 19. Notable clinical features included problematic pain (10), cardiomyopathy (5), and ventilatory failure (4). Features related to disability were (kypho)scoliosis (20) and edema/cellulitis (3) whilst comorbidities included back pain (5). Comparison of younger with older users revealed younger users had more features of muscular dystrophy affecting electric powered chair provision (56%) whilst older users had more comorbidity (37%). Tilt-in-space was prescribed for 81% of users, specialized seating for 55% and complex controls for 16%. CONCLUSIONS: Muscular dystrophy users were prescribed electric powered indoor/outdoor chairs with many additional features reflecting the consequences of profound muscle weakness. In addition to facilitating independence and participation, electric powered indoor/outdoor chairs have major therapeutic benefits. Implications for rehabilitation Powered wheelchairs have therapeutic benefits in managing muscular dystrophy pain and weakness. The use of specialized seating needs careful consideration in supporting progressive muscle weakness and the management of scoliosis. Pain, discomfort, pressure risk, and muscle fatigue may be reduced by use of tilt-in-space.

Comparison between performance with a pushrim-activated power-assisted wheelchair and a manual wheelchair on the Wheelchair Skills Test.

PURPOSE: To test the hypothesis that people using a pushrim-activated power-assisted wheelchair (PAPAW) can accomplish a wider range of wheelchair skills than when using a manual wheelchair (MWC). METHODS: We studied 30 able-bodied participants, using within-participant comparisons. Participants used a manual wheelchair equipped with both PAPAW and regular MWC rear wheels, and rear anti-tip devices (Arc-RADs) that permitted wheelie-like function. We trained participants to perform the wheelchair skills of the Wheelchair Skills Training Program (WSTP, Version 2.4). From the Wheelchair Skills Test (WST, Version 2.4), we calculated pass-fail success rates for the 50 individual skills and a total percentage WST score. RESULTS: The mean (+/-SD) total WST scores were 89.3 (+/-7.0)% for the PAPAW and 88.8 (+/-8.4)% for the MWC, with a mean difference of 0.6 (+/-5.6)% (p = 0.59). Qualitative observations suggested that skills requiring a higher force on the pushrim (e.g., incline ascent) were performed more easily with the PAPAW, whereas skills requiring greater control of the wheelchair (e.g., wheelie-dependent skills) were performed more easily with the MWC. CONCLUSION: Overall wheelchair skill performance with the PAPAW is not superior to that when using the MWC. The PAPAW may be helpful for specific skills that require more wheel torque, but the additional torque appears to be disadvantageous when performing skills that require greater control.

Rare diseases: matching wheelchair users with rare metabolic, neuromuscular or neurological disorders to electric powered indoor/outdoor wheelchairs (EPIOCs).

PURPOSE: To describe the clinical features of electric powered indoor/outdoor wheelchair (EPIOC) users with rare diseases (RD) impacting on EPIOC provision and seating. METHOD: Retrospective review by a consultant in rehabilitation medicine of electronic and case note records of EPIOC recipients with RDs attending a specialist wheelchair service between June 2007 and September 2008. Data were systematically extracted, entered into a database and analysed under three themes; demographic, diagnostic/clinical (including comorbidity and associated clinical features (ACFs) of the illness/disability) and wheelchair factors. RESULTS: Fifty-four (27 male) EPIOC users, mean age 37.3 (SD 18.6, range 11-70) with RDs were identified and reviewed a mean of 64 (range 0-131) months after receiving their wheelchair. Diagnoses included 27 types of RDs including Friedreich's ataxia, motor neurone disease, osteogenesis imperfecta, arthrogryposis, cerebellar syndromes and others. Nineteen users had between them 36 comorbidities and 30 users had 44 ACFs likely to influence the prescription. Tilt-in-space was provided to 34 (63%) users and specialised seating to 17 (31%). Four users had between them complex control or interfacing issues. CONCLUSIONS: The complex and diverse clinical problems of those with RDs present unique challenges to the multiprofessional wheelchair team to maintain successful independent mobility and community living. Implications for Rehabilitation Powered mobility is a major therapeutic tool for those with rare diseases enhancing independence, participation, reducing pain and other clinical features. The challenge for rehabilitation professionals is reconciling the physical disabilities with the individual's need for function and participation whilst allowing for disease progression and/or growth. Powered wheelchair users with rare diseases with a (kypho) scoliosis require a wheelchair system that balances spine stability and movement to maximise residual upper limb and trunk function. The role of specialised seating needs careful consideration in supporting joint derangements and preventing complications such as pressure sores.

The role of wheelchair seating standards in determining clinical practices and funding policy.

The development of international standards for wheelchair seating offers practical benefits in the process of matching technical characteristics of assistive technologies to individual user needs. However, information provided in technical test reports must be treated with caution when aggregating technical characteristics to classify products or when implementing funding policy. This article suggests that clustering technical characteristics of seat cushions in isolation of clinical and other user requirements is not a viable way to establish product funding codes that are responsive to clinical need.