The wheelchair (WC) is one of the most important examples of mobility-assistive equipment (MAE) available to patients with impaired mobility. Otherwise known as a "wheeled mobility device" (WMD), the WC has revolutionized the treatment of patients experiencing disability and has had a significant impact on those with serious functional restrictions. According to the National Institutes of Health, fifty-three million Americans lived with a disability in 2017.[1] In 2019, this number rose to over sixty-one million Americans (or 25.7% of the population).[2] Furthermore, 5.5% of the overall U.S. population used MAE in 2019 with WC use comprising 1.6%.[3] WC prescription has the potential to significantly increase the quality of life for these individuals and allow increased participation in the community. The World Health Organization (WHO) has developed guidelines that highlight eight steps to standardize the process of wheelchair service delivery. These include (1) referral and appointment; (2) patient assessment; (3) WC prescription; (4) funding and purchase; (5) device installation and preparation; (6) device fitting; (7) patient instruction and training; and, (8) follow-up maintenance/repairs.[4] 

It is important to have an understanding of the components of a WC. The main features include the seat (sling, solid, folding), wheels, tires, casters, fork & stem, leg rests, anti-tippers, wheel locks, hand rims, armrests, lap trays, seatbelt, and seat cushions. Supplementary seating options include skin protection, positioning devices, and backrest cushions. Presented here is an overview of the process of patient assessment (WHO step 2) and device fitting (step 6) for patients requiring WCs with special emphasis placed on WC fitting, seating evaluation, and the roles of the interdisciplinary rehabilitation team members. A poorly fit WC or seating system can lead to a less desirable outcome for the disabled and unforeseen consequences. As part of its WC service delivery model, the WHO has established a hierarchy of WC users' seating and positioning needs: basic, intermediate, and complex.[4] The knowledge and skills introduced in this article apply to patients with basic and intermediate level needs; patients with complex needs require specialized training and a more in-depth explanation of care delivery.

Initial Patient Evaluation

As the first step of a wheelchair seating and mobility (WSM) evaluation, an initial patient interview must take place. While a transparent, evidence-based approach to WC service delivery has been outlined in guidelines, published reviews, and textbooks, no current research supports one unified approach.[5] The key to a successful first WSM visit includes an understanding of the relationship between the WC operator, the equipment involved, and the environment.[6] It begins with an appraisal of patient-specific factors. A comprehensive wheelchair evaluation requires a thorough history and physical examination, assessment of cognition and communication skills, and evaluation of both premorbid functioning and associated co-morbidities. A patient problem list and both long- and short-term goals-of-care should be established early in the evaluation. Special focus should be placed on the patients' motor and sensory function, muscle tone, muscle strength, monosynaptic stretch reflexes, vision, hearing, postural deformities, truncal control, and range of motion. Significant deficits in any of these areas will hinder the proper operation of any assistive device. In malnourished or deconditioned patients, a nutritional assessment may be indicated. Barriers to activities of daily living (ADLs) and instrumental activities of daily living (IADLs) should be quantified to allow for on-going evaluation. Special emphasis may be placed on potential barriers and facilitators to functional mobility, including:

• Functional impairment: Contractures, spasticity and/or hypertonicity, sensory loss, paralysis and paresis, feeding issues, respiratory status, missing limb(s) (i.e., use of prosthetics/orthotics), planned surgeries (e.g., orthopedic, spine, tone management, etc.)
• ADLs: Activities oriented around self-care, such as bathing, toileting, feeding, personal hygiene/grooming, dressing, sexual activity, etc.
• Daily ADLs that are specific to patients with MAE are sometimes referred to as "mobility-related ADLs (MRADLs)"
• IADLs: Activities that support daily life and interaction with the environment, such as meal preparation, shopping, home establishment and maintenance, child-rearing, etc.
• Occupational / Vocational
• Home Environment: Home stairs, doorways, floors, hallways, tight spaces, thresholds, doorknob heights, entry ramps, rugs, etc.
• Social or Cultural Factors: Psychological, work, school, family, recreational, religious/worship-related, community, cultural, and relational needs
• Expected Transportation Needs: Vehicle and home accessibility, lifts, ramps, use of other assistive devices (walkers, canes, crutches)
• Insurance Authorization: Financial stability, socioeconomic status, access to care

The complexities of securing insurance for WC access are beyond the purview of this article. The reader is referred to other sources for a more comprehensive overview of this topic.

Wheelchair Evaluation

An appropriate WC prescription is based on patient-centered characteristics and their unique disability or disabilities. There are currently a variety of different WC types available for patients based on their body habitus and remaining motor function. Consequently, WC use has become a catalyst for innovation in biomedical engineering. The standard WC includes a 24" diameter with rear wheels and 8" diameter front casters. It typically weighs 40 lbs to 65 lbs and is designed for operator-dependent movement using the hand-rims found alongside the wheels. Its back is its primary support surface and can be adjusted depending on the support required by the patient. Other types of WCs are available for patients who cannot use their upper extremities to self-propel. Options currently available include hemi-wheelchairs, lightweight, ultra-light-weight, one-arm drive, sports-specific, standard heavy-duty (for obese clients), pediatric, traveler's, standing, and motorized wheelchairs. As always, the cost-benefit trade-offs should be considered when deciding between non-traditional WC options. Electric-powered WCs are often referred to as "power-mobility devices" (PMDs). PMDs may be further adjusted based on a patient's functional deficits. For example, patients with advanced neurodegenerative illnesses who are unable to move their upper extremities but retain digital mobility or bulbar function may adopt any of a wide variety of driving methods. These include chin control, sip-and-puff, speech control, or tongue control features for patients who are unable to control a standard joystick.

During any wheelchair evaluation, the following WC measurements must be obtained before seat fitting:

• Seat width, depth, and height
• Patient hip, trunk, and shoulder widths
• Patient shoulder and axillae heights
• WC Leg length, arm height, back height
• WC width, height, and size
• Knee-to-seat depth
• Knee-to-heel length
• Seat-to-back support angle
• Seat-to-lower leg support angle
• Lower leg support-to-foot support angle

Anthropomorphic measurements should be obtained on a mat as able while assuming a sitting position. The patient should assume a neutral, upright posture without slouching (as he or she is capable). When the patient drops their arm, their fingertips should reach the axle, indicating that the rear axle is positioned at the level of the glenohumeral joint.[7] This observation is critical for patients with manual WCs, as the incorrect positioning of the arms may impair self-propulsion. The depth of the WC seat should allow for 1.5 to 2 inches of space between the end of the seat and the popliteal fossa. The footrests should be positioned so that the patient's feet are level or slightly elevated.

During the WSM evaluation, the primary goal is to provide optimal mobility and function.[8] For this reason, frequent follow-up with a rehabilitation physician to ensure adequate fitting, maintenance, and repair (if required) is paramount, as these needs often change throughout a patient's clinical journey. The task of WC fitting is often delegated to the durable medical equipment (DME) manufacturer or a rehabilitation technology specialist (RTS) who has specialized training in this area. It is the RTS that most often takes WC measurements. Many body measurements may be obtained during the physical exam. The information accrued is used to make a final decision about the equipment to be prescribed, so additional measurements besides those listed above may be obtained (e.g., buttock-thigh depth, ischial depth, posterior superior iliac spine height, inferior angle of the scapula height, etc.).

Seating Evaluation

All WC users need a seating system that meets their unique needs. A patient should never sit directly on a seating surface (vinyl sling, solid, etc.) without a cushion. Patients with spinal cord injury spend an average of 9 to 11 hours sitting every day and often lack protective sensation.[9] Hence, inattention to any feature of the seating system may predispose to injury. The seating system used should provide adequate support while seated, maintain normal anatomic alignment while accommodating any fixed postural asymmetries, allow for adequate stability while sitting in a neutral position, promote function and the completion of ADLs/IADLs, and maximally distribute pressure. Seating systems are comprised of seats and backs, secondary supports, lateral trunk supports, head supports, and pelvic-belt supports. They are generally provided for manual or power WC bases. They include tilt-in-space, recliner, combined recliner, and tilt-in-space, or anterior tilt / lateral tilt systems. An efficient seating system should support the trunk and provide a stable seating base. Hence, the WC seat and back should both be firm. The goal of both primary and secondary support is to minimize bodyweight pressure against the skin at bony prominences in the pelvis and sacrum.

There are a variety of options for seating cushions, including foam, gel, contoured, planar (i.e., flat), pre-contoured, saddle, wedge, antitrust, pommel, or even air-filled cushions. A contoured seat appears to provide an optimal pressure distribution across the sacrum and pelvis.[10] The size and shape of the seat cushion used should be noted. The base of the WC may be a sling-style, solid, or folding type. A seating simulation is often performed by an RTS in both linear and contoured seating options. This trial allows the specialist to recommend a patient-centered seating option. Cushions that are too deep promote a posterior pelvic tilt as well as a pronounced kyphosis; seats that are too wide impair access to the wheels and hinder self-propulsion. An RTS can adequately mount seating supports, including the back, seat, and other secondary supports to the WC. A mobility simulation may also be attempted to visualize self-propulsion with the chosen cushion in place; with this information, the RTS can refine his or her recommendation, tailor it to the patient's needs and goals, and make any necessary adjustments. [NOTE: A technology trial follows in which the suggested MAE is trialed for a person/technology match (WHO step 8).] Foot supports directly affect the position of the lower extremities and distribution of weight through the trunk and onto the seat; therefore it is imperative for linear and angular dimensions recorded during the mat assessment to match.

Regardless of the seating system chosen, there are some hard-and-fast rules for any WC. For example, a WC seat should have 1 inch of space between the thighs and armrests, even if the patient has a brace or additional lower extremity orthotic in place. Additionally, the pelvis should be positioned in the chair with a slight anterior tilt so that bodyweight is distributed to the buttocks and posterior thigh. Armrests should allow for 30 degrees of shoulder flexion with 60 degrees of elbow flexion. Foot supports should be about 2 inches from the ground. They should also be mounted far enough away from the casters to avoid tips, falls, or lower extremity injuries, but not so far as to place excess tension on the hamstrings. The Tool for Assessing Wheelchair Discomfort (TAWC) is an outcome measure that includes 20 items related to patient comfort while in the WC and may be useful following a WSM evaluation.

Effectiveness of WC fitting and the seating evaluation should be demonstrated by the patient. Unfortunately, there are no universal outcome measures specific to these interventions, but some may still be useful to the WSM evaluation. The Wheelchair Outcome Measure (WHOM) and Wheelchair Skills Tests (WST) are outcome measures administered by a clinician to assess activity and participation and mobility skills, respectively, but require 30 minutes to perform. The Functioning Every Day with a Wheelchair (FEW) test takes less than 15 minutes and correspondingly assesses activity while in a WC. It includes both the WC users and clinician's perspectives and measures performance in 10 different situations. The Power Mobility Community Driving Assessments (PIDA) may be used to evaluate the indoor driving skills of a patient with a PMD. The functional independence measure,[11][12] functioning mobility assessment,[13][14] and wheelchair skills test[15][16] are other evidence-based interventions that may be used to assist in the WSM evaluation.

Any patient using MAE is at risk of injury. All members of the interprofessional rehabilitation team must understand the ramifications of an ill-fitted WC, especially for patients who plan to use their device for an extended period as there is the potential for severe morbidity.[17][18][19] A poor quality seating evaluation has the potential to aggravate the existing disease and decrease satisfaction with WC use.[20][21][22][23][24][25] Several clinically relevant risks to the everyday usage of a WC exist, including both acute (5-21% per year)[26][27][28] and chronic injury. 

Pressure Ulcers

Patients who have lost significant truncal or upper extremity motor function are at special risk for pressure-related sacral injuries. Pressure ulcers, also known as "pressure sores" or "decubitus ulcers" are areas of localized tissue necrosis due to compression ischemia from prolonged pressure on areas of the bony prominence. They are well documented in long-term wheelchair users.[29][30][31][32][33] Higher interface pressure measurements are commonly recorded at the ischial tuberosities to design pressure-relieving cushions.[34] Pressure-relief seating systems and pressure-relieving maneuvers (forward leans, side leans, WC "push-ups") are therapeutic interventions that are imperative in the prevention of pressure ulcers.[35][36] If a patient is unable to perform forward leans or side leans, special equipment or a new WC may be required.[37] In general, a pressure-reducing cushion is advisable for patients who spend significant portions of their day in their WC or who have limited ability to shift their weight.[38]

Upper Extremity Injuries

Patients prescribed a manual WC are at risk for upper extremity injury related to self-propulsion. Injuries commonly occur in the rotator cuff, medial epicondyles, and carpal tunnel. WC users are taught how to self-propel under the direction of a physical or occupational therapist. There are four common methods for self-propulsion: 1) bilateral upper extremities, 2) bilateral lower extremities, 3) hemi-propulsion, or 4) propulsion involving all extremities. The most commonly recommended technique for self-propulsion is the long forward stroke using both upper extremities. This technique forms a single-loop pattern using a stroke-and-recovery pattern; the hand-rims, not the wheels, are used for push strokes. Coupled with adequate WSM evaluation, this technique minimizes stresses placed on the wrists and shoulders from repetitive movements and avoids injury.[39] Repetitive stresses are inherent to WC use regardless of the technique used, which frequently leads to damage of the soft tissue and bony structures.[40] These injuries are often referred to as "repetitive strain injuries."

Tips and Falls

Wheelchair-related tips and falls are very common events. Data from the National Electronic Injury Surveillance System (NEISS) suggest that over 100,000 wheelchair-related injuries were evaluated and treated in emergency departments in the U.S. in 2003 and that 65% to 80% of injuries were due to tips or falls.[41] A study of non-institutionalized WC users in Nova Scotia found that of reported accidents, 46.3% were forward-falls, while 29.5% were backward-falls, and 24.2% were falls to either side.[42] Not surprisingly, falls with PMDs are not uncommon either.[43][44] Seating cushions that are positioned too high predisposes patients to tips or near-tips. Armrests that are too high cause leaning or slumping. Foot supports that are positioned too low increase the risk of tipping or interference with the floor. If footrests are not mounted far enough away from the casters, falls or lower extremity injuries may ensue. A study by Thomas et al. using rigid body dynamic models and test dummies determined that the likelihood of forward tipping was significantly reduced using a reclined backrest or a lower seat height.[45] A systematic review conducted by Rice et al. found that among wheelchair-related accidents, properties of the WC, transfers, impaired seating, and miscellaneous other environmental factors were related to WC falls.[46] They also noted that there are few outcome measures for assessing fall risk in WC users, so healthcare providers should provide comprehensive education to their clients[46] and make them aware of common precipitating factors.

Special Populations

There are a plethora of different diagnoses that might warrant WC prescription, such as a traumatic spinal cord injury, cerebral palsy, traumatic brain injury, amyotrophic lateral sclerosis or multiple sclerosis, or a cerebrovascular accident. Each injury or disability leads to specific functional deficits. Patients at any age may be affected - pediatric, adult, and the elderly included. However, the needs of patients in special populations will vary, requiring special attention to details that might change management (e.g., lifestyle, mobility restrictions, their immediate environments or stages of life, etc.). For example, children are still growing and may not have the strength or bone maturity to operate an MAE. Their tissues are still growing and are particularly vulnerable to injury. However, according to recent research, children as young as 18 months can operate a PMD. Additionally, it has been shown that early mobilization in any form has the potential to improve cognitive, visual, and psychosocial development in children.[47] The elderly are another vulnerable population owing to homeostenosis, or the decreases in physiologic reserve accompanying increasing age. They often have multiple co-morbidities that make WC usage difficult.[48] Sarcopenic changes to large muscle groups limit self-propulsion and mobility. Continence issues and decreased oral intake predispose patients to skin fragility and sacral decubitus ulcer formation.[38][49] There is always the risk of falls and fragility fractures in the aging population. Additionally, elderly patients often suffer from arthritis and are more likely than younger adults to develop shoulder injuries with prolonged WC use.[50] Not specific to the elderly population is the issue of cognitive impairment. Patients with poor memory decreased judgment or anosognosia, or other cognitive deficits pose a unique challenge to the inclusion of MAE into daily life. It is incumbent on the patients' families or caregivers to ensure safety and reinforce safe compliance with the device(s). More active patients may be appropriately fitted to a low-back WC since they retain greater mobility. By contrast, hemiplegic patients are better suited for hemi-wheelchairs or reclining WCs for better head and neck control, sleep, and improved functionality. "Hemi-height" (i.e., seat height about 2 inches lower to the ground) WCs are more appropriate for shorter patients or those who plan to propel their WC with their feet. 

Importance of an Effective Rehabilitation Team

The management of patients with disabilities is challenging and complex. It cannot be overstated that the evaluation of a patient requiring an MAE is an interprofessional process and requires input from multiple members of the rehabilitation team. The WC evaluation and WSM are specialized areas that require expertise in rehabilitation medicine. This is why an interprofessional team consisting of highly-trained physical therapists, occupational therapists, rehabilitation nurses, RTSs, and other DME specialists, rehabilitation engineers, care coordinators, and different physicians from relevant specialties is imperative to ensure favorable outcomes.[5] The WSM evaluation should assume a family-centered approach in which the needs of the patient, family members, support persons, and community members are included in the decision-making process. Outcome measures are often employed to determine whether the WC meets (and continues to meet) identified goals in the clinic and the community. Consequently, routine follow-up in the clinic is critical to assess mobility in the environment and identify barriers and their impact on the patient.

Specific Roles of Interprofessional Team Members

Physiatrists are licensed physicians trained in the care of patients with disabilities. They are medical doctors that receive training in the diagnosis, evaluation, and treatment of diseases of the muscles, bones, connective tissues, and nervous system that lead to functional impairment. They are also experts in the restoration of quality of life, often quoted as prioritizing adding "life to years" rather than "years to life." Their training includes the prescription of MAE, including WCs. They are responsible for the oversight of patients with disabilities, the coordination of care with other physicians, and are undoubtedly the leaders of the rehabilitation team.

Nurses are often referred to as the "eyes and ears of the healthcare team." Their role as bedside healthcare providers allows them to tend to patients on an almost constant basis in the in-patient setting. They are often the first healthcare provider a patient meets. Nurses establish life-long relationships with their patients and are intimately acquainted with their patient's personal needs and goals. As such, they are uniquely positioned to recognize problems, make suggestions, teach patients how to identify complications before they occur, and obtain higher levels of care (if needed). Some general preventative strategies they help to reinforce include:

• Daily skin survey over vulnerable areas
• Proper hygiene and application of emollients over susceptible regions
• Maintenance of an appropriate weight, adequate hydration, and adoption of a nutrient-dense diet
• Regular assessment of equipment, cushions, and other devices that may become damaged or incompetent with use
• Frequent follow-up with a physiatrist or other rehabilitation clinician
• Limiting unnecessary transfers and repositioning[51]
• Adoption of a home-exercise program to strengthen upper extremity and neck muscles[52][53][54]

As aforementioned, the care of patients with disabilities is complicated. Care coordinators may play a role in the assimilation of patients with WCs or other MAE back into daily life. They often handle the communication between providers, ensure timely follow up with the multiple physicians and non-physician providers that manage care, and secure insurance for MAE. They work closely with licensed social workers to schedule appointments and secure insurance. Certainly, financial constraints are an important consideration in the initial evaluation of a patient needing a WC.[55][56] Still, the specific details of this process are beyond the purview of this article. Care coordinators aid in the procurement of other assistive devices that allow mobility around the home, into and out of vehicles, and transportation. This means care coordinators partner with nurses in the recognition of potential fall risks and transportation hazards[57][58] as well as identification of physical and environmental barriers to community engagement.[58] 

Physical and occupational therapists are the mainstays of the multidisciplinary rehabilitation team. The primary goal of any physical or occupational therapist is to allow the most participation in activity as is possible. Their work is invaluable in the treatment of patients with disabilities. Both of these specially-trained providers receive doctorate-level training in the management of patients with disabilities. Both types of therapists teach other life skills that patients with MAE must adopt before reentering society, such as posture management, pressure releases, self-propulsion, the performance of a wheelie, demonstration of safe transfers out of and into WCs, etc. Physical therapists aid in the restoration of functional independence and often provide initial teaching for new WC users, while occupational therapists help patients relearn patient-centered ADLs and teach pressure-relieving seating exercises. There is a remarkable overlap in the roles and responsibilities of both types of providers, and they work in concert with one another to achieve many of the same goals. Research has shown that new WC users who received a patient-centered, multifactorial intervention administered by an expert therapist reported greater use and function with their WC.[59]

Two certifications may be obtained for WSM evaluations: the Assistive Technology Professional (ATP) and Seating-and-Mobility Specialist (SMS) certifications. They are both administered through the Rehabilitation Engineering and Assistive Technology Society of North American (RESNA). The ATP is a required certification for any RTS who has been asked to evaluate a Medicare patient requiring a power WC; the SMS is not a current requirement of Medicare.

As aforementioned, an interprofessional team approach is imperative in the management of patients with disabilities. It detects clinical and device-related problems, advocates for vulnerable patients, facilitates referrals, suggests solutions, and partners with patients to achieve their identified sense of wellbeing.[60][59] The anticipation of needs, effective communication, and frequent follow-up ensure that patients are satisfied with their prescribed device, prevent complications, and work to improve the quality of life. Follow-up is compulsory to reevaluate whether patient goals are met. It can also address any new needs that have arisen since the last evaluation. There are global recommendations that team members must reinforce before the release of a patient back into the community. For example, a visiting home nurse may arrange for a home evaluation to inspect the living establishment for safety. Since the early 2000s, there has been a growing movement known as "visibility," which seeks to broaden accessibility while allowing easier access for persons with WCs or other MAE in the home.[61] 

Homes should have a level path to an entrance without a step. Doors should be greater than 32 inches wide, and doorknobs found 36 inches from the floor to allow for manual WC to enter (these parameters are subject to change depending on the specific device prescribed). Toilets in the home should be 17 to 19 inches tall. A standard WC requires 5 feet (5' x 5') of turning space to make a full 360-degree turn, so there should be ample space in living rooms for turns. All members of the rehabilitation team share the burden of monitoring the patient and their MAE for changes that may affect their mobility in the home. There is little evidence that changing the home environment will prevent injury, but modifications similar to those suggested may decrease reliance on caregivers and caregiver burnout, especially in the elderly.[62][63] 

Importantly, patients should be able to perform three main rehabilitative activities: 1) transfer into and out of a WC, 2) performance of ADLs or IADLs, and 3) mobility. Rehabilitation therapists, the patient, and their families and caregivers are encouraged to work together toward patient adoption of these skills. Each should be demonstrated prior to discharge from healthcare facilities. Patients may also be given handouts for reference or referred to websites that demonstrate the performance of MAE skills. Professional groups, such as the Rehabilitation Engineering and Assistive Technology Society of North America (RESNA), the National Registration of Rehabilitation Technology Suppliers (NRRTS), and the Paralyzed Veterans of America (PVA), provide up-to-date and well-researched information for further study.