Chapter 32: The Prescriptive Wheelchair

Physical and occupational therapists are often called on to prescribe a wheelchair. A properly prescribed wheelchair can be a useful device in reintegrating a person with a disability into the community, whereas a poorly prescribed one can actually exacerbate the problems associated with activity limitations and disability. This chapter presents a systematic approach to determining the appropriate components of a prescriptive wheelchair, beginning with a thorough examination and culminating with a plan of care (POC) that includes the proper seating system and wheeled mobility base. The seating system and mobility base combine to create a prescriptive wheelchair, a seated environment from which the patient can achieve maximum function.

Optimal fit of a wheelchair is important to assist the person in improving mobility, posture, and function. Properly fitted wheelchairs assist with preventing problems associated with poor posture, including pressure sores, respiratory difficulties, discomfort, and abandonment of equipment. Cosmetics (appearance), durability, weight, and intended use need to be considered when determining the most appropriate wheelchair system.

Determining the appropriate wheelchair and seating system requires a thorough examination to ensure optimal equipment is obtained. Too often, a basic commercial system is provided, but this is frequently not the best solution. The solution must consider multiple patient-, environmental-, and diagnosis-related factors and requires a comprehensive examination by the professional team. The examination is time consuming and may require several sessions to complete. However, additional time provided "up front" will decrease errors and future costs associated with the mistakes created by data obtained from a less than optimal examination.

Wheelchairs are not just mobility devices but are also seating support devices. If inappropriate seating supports are provided, the end user (i.e., the patient) may be unable to propel a manual wheelchair, operate a power wheelchair, or achieve effective positioning at a table for meals. All relevant aspects of a person's lifestyle should be considered to ensure safety and optimal function.

The entire team contributes to the wheelchair prescription decision making. It is important that all those concerned with the person's present and future function be a part of this team. The team may include the wheelchair user, therapists, family members, caregivers, nurses, physicians, educators, vocational counselors, and a qualified rehabilitation technology supplier. To ensure that the most suitable device is obtained, the team must have a clear idea of who will be using it, what functional level is expected, and where the chair will be used. Team members contribute to the examination reports and letter of medical necessity, which must be prepared to secure funding. Once the chair is supplied, the appropriate team members are responsible for adjusting and fitting the final device, as well as teaching the patient and any caregivers how to use and maintain the unit to ensure optimal long-term performance.

A prescriptive wheelchair is a combination of a postural support system and a mobility base that are joined to create a dynamic seated environment (Fig. 32.1). The postural support system is made up of the surfaces that contact the user's body directly. This includes the seat, back, and foot supports, as well as any additional components needed to maintain postural alignment. Maintenance of postural alignment may require such additions as a head support; lateral supports for the trunk, hips, and knees; medial support for the knees; and upper extremity (UE) support surfaces, as well as straps (e.g., anterior chest or pelvis) needed to keep the user interfaced with the support surfaces. The mobility base consists of the tubular frame, armrests, foot supports, and wheels. Once the decisions are made about the type of support system needed, the team must then decide what type of mobility base best suits the user's functional level and environmental needs. Clear information will be needed to ensure that the postural support system and the mobility base interface properly. For users who utilize more than one mobility base (e.g., power and manual), the most cost-effective approach is to have one support system interface with all the mobility bases. This is not always practical, and sometimes it is best to have the full-support system on the chair used most frequently, and forgo optimal postural support in the backup system used to facilitate transport for short trips.

Creating a dynamic seating system involves several important steps:

• Gathering background information, including diagnosis, prognosis, functional skills, anticipated goals, and expected outcomes

• Performing a comprehensive examination

• Conducting seating simulations (testing linear and angular dimensions determined from the mat examination in a seating device with the ability to add postural supports to assist in determining optimal seating supports) and equipment trials (testing manual wheelchairs, power wheelchairs, and/or seating supports and cushions before ordering equipment)

• Developing a POC that includes appropriate recommendations and product choices

As noted, the overall desired outcome is to create a dynamic seating system that provides a comfortable base from which the user can attain maximum function. Before the examination, team member expectations should be discussed. A great deal can be learned at this point about what the various team members hope the system will be able to do for the patient. It is extremely important that all issues are identified and openly discussed before the process is begun. Patients, family members, or caregivers may assume that the wheelchair and seating system can achieve unrealistic goals (e.g., normalize posture, provide total pain relief, allow independent transfers). When these unlikely goals are not met, these individuals are often so disappointed that they cannot see the other benefits of the system. Early, open discussion is critical to the decision making process.

History Taking

Background information is an essential part of the examination process. During the history taking, one can determine what seating and mobility options have been successful in the past, as well as those that have been unsatisfactory; initial goals and concerns related to the new equipment can also be identified. All areas (patient, environmental, and diagnosis related) that require compatibility or interface with the mobility and seating support system should be discussed. For instance, if someone uses a van for transportation, door opening size and seat setup should be discussed. Moving from one style of chair to another might prevent easily getting through the van door if the individual is sitting taller in the new chair or experience difficulty turning the chair once inside the van owing to increased length of the new wheelchair.

Of considerable importance is knowledge of how positioning of one body part affects another. Impairments of a single joint or body segment can directly affect sitting position and alignment. For example, if there is inadequate hip flexion, what happens to the body when in a seated position? Is there any chance that limited range of motion (ROM) will change over time? Can adjustability be built into the seating system to accommodate changes? Should other positioning programs be instituted in addition to seating to assist with improving ROM?

Information about past and future surgeries should be gathered to have a better understanding of current seating needs as well as to gain insight into future requirements. For example, a person who has undergone a spinal fusion may have a pelvic obliquity that cannot be corrected and requires accommodation in the seating system. A person who has had hip surgery (e.g., femoral osteotomy, total hip replacement) may have a leg length difference and the seat cushion needs to accommodate the difference in leg lengths. A person with hip pain may require a seating design to accommodate ROM limitations that may be the cause of the pain. After completing the mat assessment but before completing the seating assessment, it may be necessary to consult with the physician regarding tone management, pain management, or other surgical intervention that may be necessary. A person with multiple sclerosis (MS) with increased lower extremity tone may have significant knee ROM limitations that need to be addressed before seating in a wheelchair. A baclofen pump may be necessary to control tone and assist with increasing ROM before completing the assessment for the seating system. A person with cerebral palsy (CP) may have significant hip ROM limitations that require surgical intervention to improve sitting posture.

Overview: Tests and Measures

Strength and Endurance

Gross and fine motor skills are examined to determine the amount of support a person needs for seating. Strength, endurance, and their impact on function should be addressed within the context of the person's day. A person might function well for 1 hour in the morning and need minimal support during that time but may need more support in the afternoon owing to poor endurance and fatigue. This may make a difference in the ability to perform functional activities throughout the day.

Sensation and Skin Integrity

Individuals who use a wheelchair for locomotion have an increased chance of developing pressure sores from prolonged sitting. The ability to change position or to request positioning changes (if unable to perform independently) based either on a timed interval or due to discomfort is important in the prevention of pressure sores. Individuals with decreased sensation (e.g., spinal cord injury [SCI]) are unable to perceive discomfort from prolonged positioning. In such situations, positioning changes should occur at timed intervals and be incorporated into the daily schedule.

Location and size of old wounds should be noted to ensure appropriate pressure-relieving strategies are provided. Location of new wounds must be investigated to determine the cause (e.g., faulty bed or wheelchair positioning). The proposed seat cushion and back support should be examined and evaluated to determine their potential for promoting healing of any current pressure sores and preventing development of new pressure sores. Pressure mapping is accomplished using a special piece of material with sensors combined with computer software that shows high- and low-pressure areas when sitting on a specific cushion. This map can be used to assist in determining an appropriate seat cushion and is beneficial as a teaching tool when providing instruction in using a tilt-in-space feature, a recline feature, and any adjustments to the seat cushion. When using the tilt feature and recline feature, the pressure on the map changes and areas of high pressure will diminish, assisting individuals in understanding the need for changing their position. Various cushions can also be tested to assist the examiner and individual in choosing the most appropriate seat cushion based on pressure distribution.^1,2,3

Vision and Hearing

Vision affects ability to drive a power wheelchair and to maneuver a manual wheelchair. Visual impairments may be more apparent outdoors rather than indoors. It is important to determine how visual problems affect mobility and to determine if the person can learn compensatory techniques to be independent and safe.

Hearing deficits can also pose safety concerns. If driving outdoors, a person with a hearing impairment may not hear a car horn or someone calling to them to stop. Various headrests may diminish the ability to hear well. Determining optimal equipment to compensate for hearing loss is important for safety and independence.

Health Status

Poor positioning of the pelvis and trunk can increase the risk of developing urinary tract and respiratory infections. Complete bladder emptying is more difficult if a person sits in a posterior pelvic tilt. Other risk factors for urinary tract infections include poor technique during intermittent catheterization or changing of indwelling catheter. If a person sits with a kyphotic or scoliotic spine, breathing is compromised and clearing lungs of secretions is more difficult, which increases the risk for respiratory infections.^4,5

Nutrition has a direct impact on overall health. Poor nutrition can increase healing time, increase risk of developing pressure sores and infections, and create weight management problems. Impaired swallowing will also affect nutrition. Weight gain and loss either from food intake, gastrointestinal tube placement, or medications should be discussed to make informed decisions about seat width of the wheelchair.

Functional Abilities

Toileting

Bathroom issues should be addressed to determine if the person uses a toilet, urinal, catheter, or protective undergarments. If using the toilet, the ability to transfer from the wheelchair to and from the toilet will be important. The effect of the seat height on transfers and the ability to swing away the footrests to approach the toilet must be considered. If using a urinal, the seat style needs to be discussed to prevent accidental tipping of the urinal. If using a catheter and the person empties the urine collection bag into the toilet, access to the toilet needs to be discussed. If the person frequently experiences urinary accidents, a waterproof cover on the seat cushion may be considered.

Bathing and Washing

Accessing the bathroom sink, bathtub, and shower is more difficult when sitting in a wheelchair. Many bathrooms are small and it can be difficult or impossible to maneuver in this space. Concerns include seat height for transfers, style of footrests for transfers, and access to sink for washing. Bathroom modifications may be needed for safety and improved access (see Chapter 9, Examination of the Environment).

Dressing

Some individuals find it easier to don clothing when in their wheelchair. Footrest and armrest style and durability need to be considered to ensure the system will accommodate the extra weight placed on both these components during dressing activities. Use of tilt-in-space seating or a reclining back system may benefit the person who dresses in the wheelchair.

Eating

The seat and armrest height of the wheelchair may preclude positioning the wheelchair at some tables or desks. The style of table or desk may also interfere with access (e.g., number and arrangement of legs, height of working surface, presence of drawers). If a person needs assistance during mealtime, caregivers need to have ease of access. Positioning of head/neck and trunk alignment is important while eating to ensure a safe environment, optimize swallowing, and minimize choking potential.⁶ Power seat elevators can increase access to tables of varying heights.

Communication

Some patients require alternative forms of communication. Consultation with the speech-language pathologist is important to determine the type of communication device being used and the method of mounting the device to the wheelchair. This may include a tray to support the device or a separate mounting system attached to the wheelchair. Switches may be used to operate the device; mounting of switches will need to be determined to ensure optimal access and ease of use.

Transfers

The type of transfer used is another important consideration when prescribing a wheelchair. The patient's transfer performance (e.g., complete independence, supervision, moderate assistance) will affect selection of wheelchair features. Armrest style, footrest style, trunk support style, and seat height can all influence safety, as well as the type and amount of assistance required.

Ambulation

Although a person requires a wheelchair for long-distance travel, he or she still may be able to ambulate short distances. The person needs to be able to stand up from the wheelchair and access the assistive device. The seat height, footrest style, and armrest style are important to ensure safe standing and seating to and from the wheelchair. An assistive device (e.g., cane, crutches, walker) may need to be attached to the wheelchair via a special holder and the optimal method of access determined.

Wheelchair Mobility—Manual and Power

Wheel position is important for independent manual mobility. If the feet are used to propel the chair, seat height is important to ensure that the feet reach the floor and to prevent the person from sliding down in the wheelchair. Hand control position is important for independent power mobility. If unable to use a standard hand control, other drive controls are available; strategic placement of alternative controls will assist in providing independent power mobility. If the person is dependent and caregivers are moving the wheelchair, the style of push handles and wheel locks is important.

Environmental Issues and Transportation

Many issues affect a person's ability to access his or her environment. Stairs interfere with access, as do narrow doorways. Small elevators will affect a person's ability to move safely in and out of the elevator, as well as access the push buttons to reach various floors. Transportation also affects access.⁷ Wheelchairs may need to be folded for car transport. Van transportation can be difficult as well. The doorway opening and tie-down system inside the van can affect safety. Although it is safer to have a wheelchair facing forward, some vans are equipped with tie-down systems for the wheelchair to be oriented side-ward. This can make it more difficult for a person to maintain a safe sitting position. Wheelchair frames and wheels are not designed to withstand the forces generated in a crash when a chair is oriented sideward. There is inadequate support to the individual when oriented sideways and there is a greater tendency to fall/tip sideways causing injury. The person may transfer into a regular seat once inside the van; safe storage of the wheelchair is then a consideration. Steep or stone driveways, dirt roads, potholes, and lack of beveled curbs will all adversely affect a person's ability to safely access the community.

Cognitive and Behavioral Issues

Cognitive and behavioral issues can affect the type of equipment provided to a person with disabilities. The person may be extremely rough on equipment and/or may use equipment as a weapon to hurt others. When providing various types of equipment, safety should always be considered first. Large rehabilitation centers often have programs in place to address these types of issues.

Seating principles provide important general guidelines for patient positioning in a seating device. The overarching intent of the principles is to maximize function by promoting comfort, stability, and optimal interaction with the environment.

Principle 1: Stabilize Proximally to Promote Improved Distal Mobility and Function

This principle is a basic underlying strategy and commonly used by therapists treating individuals with neuromuscular involvement. Stabilizing proximally provides a foundation for distal movement. When eating, stabilizing an elbow on a table and then stabilizing a wrist may promote independence during meals. To improve trunk posture, stabilizing the pelvis is important. In sitting, pelvic stability should be addressed first because it is the foundation for the rest of the body. When assessing how much or where stability is needed, start with the pelvis and move down, then up, and reassess at each level to determine where active control and skill development is needed, as well as the amount of support needed to maintain good posture.

Principle 2: Achieve and Maintain Pelvic Alignment

The pelvis should be positioned in a neutral to slight anterior tilt and optimally be level (not oblique or rotated). This position allows for maintaining the normal lumbar curve, provides weight-bearing on the ischial tuberosities, and promotes active trunk ROM and co-contraction of trunk muscles. Weight-bearing on the ischial tuberosities also promotes symmetry and provides a more stable upright position (rather than sitting on the sacrum or coccyx). Promoting flexion at the hips and extension in the low back can be effective in decreasing abnormal tonal patterns. A level pelvis allows for equal weight-bearing and even pressure distribution and improves alignment in body areas above and below the pelvis. To achieve good pelvic alignment, ROM limitations must be accommodated, as well as all linear dimensions (e.g., thigh and calf length, trunk and hip width). To maintain this alignment, pelvic positioning devices may need to be considered. A pelvic positioning device is a flexible strap or rigid bar that assists in controlling pelvic movement. A flexible strap should lie just below the anterior superior iliac spines (ASISs), be very snug, and be at a 45° to 90° angle to the seat surface. This angle of pull is dependent on how the person moves the pelvis. Key considerations for the pelvic flexible strap positioning device include placement or angle, size, method of cinching, direction of pull, and location of buckle. A rigid device should lie just below the ASISs (also called a sub-ASIS bar) with the bar attached to metal brackets that mount to the seat or frame of the chair. This device prevents pelvic movement and may be beneficial for an individual with excessive pelvic shifting.⁸ Another method to maintain pelvic position is to use knee blocks. The knee blocks provide anterior support to the knees and prevent the individual from sliding forward in the wheelchair.

Principle 3: Facilitate Optimal Postural Alignment in all Body Segments, Accommodating for Impairments in Range of Motion

Once the pelvis is stabilized, attention is directed toward alignment of other body segments. Good alignment promotes improved balance, stability, comfort, and function; helps prevent deformity from habitual asymmetrical posturing; and prevents skin breakdown from uneven pressure. To achieve optimal alignment, it must be determined if improved alignment can be achieved passively on a mat table and then in the seated position. If good alignment can be achieved, it must be determined whether the person can maintain alignment using muscular effort or if external supports are required. Time must be allocated to practice motor skills and movements within the context of improved postural alignment, especially if dramatic alignment changes have ensued. For joints and/or body segments that are not amenable to passive alignment, accommodation is needed (e.g., fixed contractures). For example, accommodation would be needed for a person who presents with long-standing hip ROM limitations from prolonged sitting in a windswept lower extremity (LE) posture (one hip in abduction and external rotation and the opposite in adduction and internal rotation). Attempts at aligning the LEs would cause pelvic rotation and trunk rotation. The LEs must be positioned in the windswept posture. Alignment of the pelvis takes priority over alignment of other body segments. Providing optimal pelvic and trunk alignment is most important.

Principle 4: Limit Abnormal Movement and Improve Function

Seating equipment can be designed to inhibit abnormal tone, postures, and movements and to improve health, comfort, and function. Abnormal movements should be discouraged or blocked (controlled) based on anticipated goals and expected outcomes. Observation and analysis of abnormal movements will provide clues to what triggers the response. Determining initiating triggers will inform decisions about seating strategies that may contribute to inhibiting unwanted movement. This requires good problem solving skills. Determining the source of the problem may allow decreased use of support blocks.

Principle 5: Provide the Minimum Support Necessary to Achieve Anticipated Goals and Expected Outcomes

The patient is provided the least restrictive supports required to facilitate the acquisition of new skills and foster independence rather than create unnecessary dependence on equipment. This is especially important to the younger person who is growing and changing, as well as the person who has not had the opportunity to improve function owing to poor positioning and excessive equipment use. Supports can be used intermittently throughout the day to provide learning opportunities (acquisition of new skills) over time. Using a minimum of supports can improve cosmetic appearance and self-esteem. Other equipment may need to be used for specific activities or for opportunities to improve strength and skills.

Principle 6: Provide Comfort

Seating equipment should be comfortable. Discomfort leads to increased abnormal tone and movement, postural asymmetry, and fatigue; decreased endurance, attentiveness, and concentration; and finally disuse of equipment. Critical to the provision of equipment is involvement of the user who should participate in the process and be allowed an opportunity to express likes and dislikes of the system. A poorly fitting system only creates more problems for a person who is already making lifestyle changes to accommodate his or her activity limitations.

The physical therapy data collection for a prescriptive wheelchair includes determining level of function and posture in existing equipment, performing various measures on a mat table, and performing a seating simulation. If significant changes are being made to a seating system, the simulation will provide the patient an opportunity to "test" and provide feedback about the seating recommendations.

It is important to take time at the beginning of the examination process to explain to the patient and caregivers what will be happening, what information will be gathered, and why the information is important. Everyone should be made to feel that his or her input is necessary and valuable. Time should be allocated during data collection for comments or questions from the patient, caregivers, and other team members. Before each stage of the process, the patient should be asked if it is acceptable to proceed. For example, "I would like to put my hands on your pelvis, is that okay?" It is important to move slowly and speak calmly, because quick movements or loud speech may increase anxiety. For some patients, this may increase muscle tone, interfering with data collection. It is important to explain what is being observed or measured so that patients and caregivers can understand information exchanged among team members, and so they can fully comprehend the team's findings and the subsequent recommendations.

Although time consuming, it is absolutely critical that the physical examination be complete and accurate because changes may be difficult to make later. Accurate recording provides a permanent record of why certain decisions were made. During the ordering or manufacturing process, additional decisions concerning modifications may be needed. If accurate measurements are on file, decisions can often be made without recalling the person to the clinic.

Function and Posture in Existing Equipment

Observing the patient in his or her existing wheelchair provides a great deal of information. The patient should be in the best or most commonly assumed position, with supports and straps in place. Questions should include how the patient and/or caregiver perceive the device is working; has it always worked like this, or has its function decreased over time? If it worked well initially, but does not work well now, is this because of patient change

(weight gain or loss, growth, functional gain or loss) or equipment change (broken or missing parts, decreased reliability)? Information can be gathered during this portion of the examination about patient and caregiver attitudes and technology savvy, as well as their physical use of the equipment. Throughout the initial visit, team members should continuously observe the existing equipment, the patient, the caregivers, and their physical and psychosocial interactions.

The team should gather data about the patient's postural alignment at the head, shoulders, trunk, pelvis, and LEs using both visual observation and palpation. Pelvic alignment is examined by palpation along the pelvis crests and on the ASISs. The position of the pelvis (e.g., rotation, posterior or anterior tilt) should be carefully documented.

With the patient's shirt removed or at least lifted to nipple level, trunk posture can be observed directly. A combination of visual observation and palpation will allow determination of alignment (for example, abdominal wrinkles usually mean a rounded spine). In the presence of abnormal alignment, the therapist should determine (1) if alignment can be corrected using gentle pressure; and (2) what factors may be interfering with good postural alignment.

The patient should transfer onto a mat table. Observation of the specific transfer method used and level of assistance required will avoid creating a new system that interferes with this function.

Mat Table Measures

Supine Position

The supine examination provides an opportunity to learn about the person's strength and range of available movement, as well as how movement of one body part affects tone, comfort, position, control, and performance in other body segments. The goal is to preserve spinal alignment whenever possible, maintaining the natural lumbar curve whenever it can be produced. The person should be examined in a gravity-minimized position (supine [preferred] or side-lying) to determine if ROM limitations exist. This position also allows preliminary linear measurements, including thigh length, calf length, trunk width, and hip width.

The supine examination usually requires more than one examiner. The patient should be positioned supine on a firm surface (a mat table or carpeted floor works well; a bed may not be firm enough). The range of available pelvic and hip movements as they relate to spinal and pelvic alignment should be determined. The purpose is to determine the maximum ROM available before spinal and pelvic alignment is disturbed.

Range of Motion

Hip flexion, knee extension with hips flexed, and ankle dorsiflexion with knees flexed are the most important LE ROM values to obtain.^9,10 A complete ROM examination of both UEs and LEs, head/neck, trunk, and pelvis is needed since limitations in these areas will affect a person's ability to propel the wheelchair, position the head for safe eating, and sit with good upright alignment.

Hip flexion is measured with the person in the supine position (Fig. 32.2). Knees should be flexed to decrease the influence of the hamstring muscles. The pelvis should be in a neutral to slight anterior tilt position. Both hips should be flexed slowly keeping one hand flat under the lumbar/sacral area of the person's spine until posterior movement of the pelvis (out of a slight anterior tilt) is felt. The end of hip flexion ROM for seating is defined as the angle of hip flexion just before the pelvis moves posteriorly.

Goniometric values for hip abduction, adduction, and internal and external rotation should also be obtained. If the pelvis is oblique or rotated, it may be necessary to allow the LEs to assume the windswept position, or be abducted before measuring hip flexion. The goal is to achieve neutral pelvis alignment before measuring and to ensure that the pelvis does not shift into a posterior pelvic tilt, obliquity, or rotated position during the examination.

Knee extension is measured with the person in the supine position with both hips flexed to the optimal angle determined (above) and the knees initially flexed (Fig. 32.3). While maintaining the hip angle and keeping one hand under the lumbar/sacral area of the spine, the knees are extended slowly toward the ceiling until the pelvis begins to move or excessive tightness/tension is felt in the hamstrings. It is especially important to maintain the appropriate hip position while extending the knees since the hamstring muscles are a two-joint muscle and the amount of range achieved is dependent on the position of the hips.¹¹ When the hips are extended, knee extension range tends to be increased and when the hips are flexed, knee extension range tends to be decreased due to hamstring muscle tightness.

Ankle dorsiflexion ROM is also measured in the supine position. Hips and knees should be positioned in available hip flexion and knee extension alignment (as determined above). The ankle should be maintained in a neutral inversion/eversion position and an attempt made to achieve neutral dorsiflexion/plantarflexion position at the ankle. The gastrocnemius muscle is a two-joint muscle and ROM at the ankle is affected by the position at the knee. If the knee is extended and muscle tightness is present, decreased dorsiflexion is noted. With the knee flexed, increased dorsiflexion is achieved. Although it is important to measure ROM with knee extended (bed positioning, standing, and ambulation), this is an assessment for seating and muscle tightness limitations must be addressed in a simulated position on the mat to better understand posture achieved in sitting.

Range of motion of the spine, head/neck, and UEs should be examined to determine the impact of limitations on posture. If significant scoliosis exists, decisions will need to be made regarding method to support the scoliosis and obtain optimal trunk position because this will affect pelvic position. Contractures in the neck region affect head position. Attempts to align the head with a lateral flexion contracture may cause the trunk to shift to the side. Once the trunk shifts, the pelvis and LE positions will be affected. The UE position becomes critical when determining ability to propel the wheelchair or if specific UE positioning (e.g., support surface) is required to maintain current ROM.

Other measurements needed when the person is supine include thigh length, calf length, and pelvic width. These will be starting point measurements for testing in a seated position.

Thigh length measures are taken in supine on a mat table or other firm surface with the hips and knees in the optimal position determined above. The measure is taken from the mat surface to just before the popliteal fossa (Fig. 32.4). Accuracy is important in measuring thigh length. If the measurement is too long, it will be difficult to get the hips fully back on the seat and properly supported in the wheelchair; this will create problems over time. If the person has a windswept or abducted lower extremity posture, measure on a straight line to the shortest side. If needed, use a clipboard or other firm surface to act like the seat surface for more accurate measuring. Leg (calf) length should be taken when the person is supine on a mat table. The hip, knee, and ankle should be positioned as previously determined. Measure from the popliteal fossa to the bottom of the heel to determine leg length. For increased accuracy, remeasure in the sitting position with appropriate footwear. Preliminary measurement for pelvic width should be taken in the supine position. This is the widest portion of the hips from one greater trochanter to the other. Final measurement needs to be completed in the sitting position owing to soft tissue spread.

Seat to Back Support Angle

Measuring hip flexion will assist in determining the trunk to thigh angle and ultimately the seat to back support angle^12,13 (Fig. 32.5). If hip flexion is to 75°, the trunk to thigh angle is 105°. In addition to the trunk to thigh angle, other data needed to determine the final seat to back support angle include the center of mass of head and trunk over the sitting base, body contours, tone, movement patterns, and comfort. The combined information guides determination of the final seat to back support angle. For example, if hip flexion is to 95°, the trunk to thigh angle is 85° (Fig. 32.6A). However, this position may not provide good stability, resulting in trunk flexion and making it more difficult to maintain an upright sitting posture (Fig. 32.6B). In this example, the patient may need a final seat to back support angle of 100° to address center of mass, body contour, and comfort issues (Fig. 32.6C). Many times the trunk to thigh angle will be the seat to back support angle, but tone, movement, and comfort should not be overlooked when finalizing this angle.

Seat to Leg Support Angle

Knee extension ROM assists in determining thigh to leg angle (Fig. 32.7). The final seat to leg support angle is determined by considering the thigh to leg angle, abnormal tone, movement patterns, and comfort^12,13 (Fig. 32.8). Hamstring muscle tightness must be accommodated to prevent the pelvis from shifting into a posterior pelvic tilt. Many people will require a seat to leg support angle of 90° or less to accommodate hamstring tightness or fixed knee flexion contractures to maintain a neutral pelvic tilt position.

Lower Leg Support to Foot Support Angle

Ankle dorsiflexion ROM assists in determining lower leg to foot support angle (Fig. 32.9). The final lower leg to foot support angle is determined by considering ankle ROM and deformities and abnormal tone and movement patterns^12,13 (see Fig 32.8). The use of ankle-foot orthoses (AFOs) will also affect the final lower leg support to foot support angle.

Seated Examination

Seated examination using a simulator allows testing of hypotheses generated during the supine examination and provides an opportunity to determine patient tolerance to the recommended angles and to check if the thigh length is accurate.¹⁴ The ideal simulator chair has an adjustable seat to back support angle, seat to leg support angle, and lower leg to foot support angle and the ability to adjust seat depth, calf length, and trunk length. Other features of an optimal simulator include the ability to add lateral trunk supports, lateral knee supports, medial knee supports, arm supports, head supports, and other support surfaces to determine optimal positioning. An adjustable chair provides the evaluator with the ability to use the chair for a variety of people to determine optimal sitting posture. The ability to tilt the wheelchair assists in assessing the effect of gravity on the patient.¹⁵ A planar seating simulation chair is available commercially specifically for assisting therapists in determining positioning needs (Fig. 32.10). If unable to obtain this specific chair, a tilt-in-space and recliner wheelchair can be used for testing, but care should be taken to obtain the necessary seat to back support angle, thigh length, and wheelchair width if using this type of system for seating simulation.

Seating simulation provides the opportunity to observe tone and movement, alignment, and function. Supports may be added and subtracted to assist in determining if a person tolerates more or less support. Changing the amount of tilt influences the impact of gravity on a person's ability to sit upright. Finally, asking the person how he or she feels and working together assists in improving posture, comfort, and function.

Some aspects of seating simulation can also be performed while seated on a mat table. The examiner's hands are used to determine amount of support and location of supports. Trunk strength and balance can be assessed while sitting on the mat table, but if the person has significant physical involvement, it is very difficult to accurately determine seating supports needed in this position (Fig. 32.11).

Using a simulation chair in the supported sitting position, all angular dimensions should be finalized, including seat to back, seat to leg, and lower leg to foot support angles. The linear dimensions need to be finalized as well (Fig. 32.12.) The examiner should remeasure the sitting depth from behind the buttocks to the popliteal fossa (Fig. 32.12A). This may differ from the supine measurement, and careful examination should reveal whether the difference is secondary to correctable postural difficulties or simply variable flesh distribution in sitting versus supine. Leg measurement (Fig. 32.12B), from the popliteal fossa to the heel with customary footwear in place, will be needed to determine footrest length on the wheelchair. The sitting knee flexion angle should also be documented (Fig. 32.12C). Measurement of back height should be taken from the sitting surface to the posterior superior iliac crests (Fig. 32.12D), lower scapula (Fig. 32.12E), top of the shoulder (Fig. 32.12F), occiput (Fig. 32.12G), and crown of the head (Fig. 32.12H). These measurements will provide a detailed record should decisions regarding wheelchair back height be needed once the examination is completed. Measurement of the hanging elbow (Fig. 32.12I) is needed to determine proper armrest height. With the person in a corrected sitting position, the UE is positioned at the side of the body with 90^o of elbow flexion and the shoulder in a neutral position. A measurement is taken from the bottom of the elbow or forearm to the sitting surface.

During the seated examination, measurements should be taken of width (Fig. 32.12J) and depth (Fig. 32.12K) of the trunk and width (Fig. 32.12L) of the hips for decisions regarding support accessories and width of the seating system and the mobility base. If the patient is seated asymmetrically, it will be necessary to measure across the widest span of the patient's seated body (e.g., outside hip on the adducted side to outside knee of the abducted leg). A measurement of foot length (Fig. 32.12M) should also be taken. To ensure accurate recommendations it is important to consider orthoses, clothing, and recent weight loss or gain, as well as the patient's potential for growth, when recording these measurements. If it takes more than a few months to secure funding it may be necessary to remeasure the client before placing the order.

Wheelchair Testing

Once optimal positioning is determined, discussion can then follow regarding functional needs of the wheelchair user that need to be addressed, such as eating, communication, computer access, switch access, manual and/or power mobility, or transfers.

Time should be allocated for testing trial equipment in the clinic setting. This provides an opportunity for the patient to determine personal tolerance to the recommended changes. If possible, testing of trial equipment should be done in the patient's home environment and community to allow the patient to practice using the equipment and ensure that the equipment meets the expected outcomes.

The data gathered during the physical examination, seating simulation, and wheelchair testing are now analyzed to determine equipment parameters based on specific client-centered goals. Discussion ensues to determine if the client is functioning at highest potential or if additional support would help to improve function of distal body parts.^16,17 Each piece of equipment provided needs to be justified; for example, justification for lateral knee supports might be the need to maintain neutral alignment of the LEs or the need to prevent excessive active hip abduction. For each component required for postural support, mounting location, method of stabilization, strength, and durability must be finalized. For example, lateral trunk supports might be needed for postural support but will interfere with a sliding board transfer. Swing-away hardware will move the support out of the way, but the specific hardware to use is dependent on the ability of the client or caregiver to access the hardware and shift it out of the way. Testing of these details is important to ensure that maximal independence is achieved with the new equipment.

Problem Solving Model

A problem solving approach can guide selection of needed seating features by using a sequence of(1) identification of equipment-related clinical problems; (2) establishing objectives for equipment intervention; (3) making equipment property recommendations; and (4) identification of equipment specifications.^18,19 Box 32.1 provides an example of this strategy.

It can assist in guiding the thought process and ensuring that all issues are addressed. This allows thoroughness and improves the ability to articulate reasons for choosing specific wheelchair components. The process is patient centered rather than product centered and will assist in obtaining optimal equipment.

Clinical Problems, Objectives, Property Recommendations, and Product Specifications

Clinical Problems

Information needed in this area includes data obtained from history, preliminary examination, supine and seated examinations, and determination of functional abilities to preserve and functional abilities to attain.

Objectives

Goals should be set related to positioning and alignment, motor control, health, function, environmental issues, and social/emotion issues. Goals can be general (e.g., improve skin integrity) but will need to become more specific (e.g., reduce pressure under left ischial tuberosity to prevent pressure sores in this area) to determine equipment properties.

Property Recommendations

Consideration is given to the different surfaces and features of the equipment. Properties are the specific details of the final product. The surface shape and flexibility, dimensions, placement, and attachment features should be included in this section. Careful consideration of properties will ensure a final product that promotes optimal independence.

Product Specifications

The list of property recommendations will be reviewed to determine the final product. If no commercial option is available with the needed properties, determination of a method to customize is needed. The supplier should be knowledgeable and be able to assist the therapist in obtaining the most appropriate equipment to address all needs.

The benefit of using this decision making process is to help keep the process client centered rather than product driven. It promotes problem solving and improves accuracy when choosing final product components.

When using this process, the person's diagnosis assists in determining specific properties of final equipment, as well as the priority of the properties. If working with someone with an SCI with previous pressure sore problems on the buttocks, the properties of the seat cushion become important. If working with someone with progressive MS, the ability to modify the equipment over time will be important. When considering the patient's medical diagnosis, it is important to determine if the condition is stable and if not, the type of changes that are expected. If the medical condition is stable but the person is newly injured (e.g., SCI), changes to equipment may be needed over time as the person adjusts to using a wheelchair for primary mobility purposes. If working with someone who is stable and has always done things one way, it is important to provide him or her with other options and determine if poor habits can be changed.

A well-planned seating system may be able to normalize tone, decrease pathological reflex activity, improve postural symmetry, enhance ROM, maintain and/or improve skin condition, increase comfort and sitting tolerance, decrease fatigue, and improve function of the autonomic nervous system. In addition, the base of the seating system can allow for changes in orientation in space (recline and tilt). A properly prescribed mobility base will improve access to the physical environment (both manual and power-activated), whether alone or with a caregiver. It should be effective for accomplishing all home, school, work, and recreational activities and, where necessary, assist the caregiver with patient management.

When setting priorities, it is important that clinical team members do not overload the patient with their professional opinions. Clinical teams may not be fully aware of the barriers facing the individual using a wheelchair in his or her physical environment. Clinicians may observe a patient ambulating in the clinic and feel that with added practice he or she could ambulate full time. This clinician may consider recommending crutches and a simple manual wheelchair. In the patient's real environment, however, long distances may need to be traversed to independently shop, attend community activities, and function at school or work. Walking to these activities would require extraordinary effort, and propelling a standard manual wheelchair may not offer much additional assistance. A motorized scooter or wheelchair may be more effective as a supplement for environmental mobility.

Postural Support System

The components of the system that will directly affect comfort and maintenance of posture are the seat surface, back surface, pelvic positioner, UE surface, and LE surfaces. These areas should be addressed together as the postural support system. Increased contact between the user and the support surfaces increases comfort and control and decreases pressure over bony prominences.^20,21,22,23 The continuum of available support surfaces runs from firm planar surfaces (wood, firm foam) (Fig. 32.13), through deformable surfaces (knit-covered foam) (Figs. 32.14 and 32.15), and contoured surfaces (Fig. 32.16), up to and including custom-molded surfaces (Fig. 32.17).

Angular relationships between the surfaces at the hip and knee joints (thigh and back surfaces, thigh and leg surfaces) previously determined during seating simulation must be included in final setup of postural support surfaces. This information will allow the planned intervention to accommodate limitations in ROM, ensure proper alignment of body segments, and minimize pressure distal to the joint. Changes of orientation in space (fixed or dynamic) affect the user's comfort level, pressure over skin surfaces, fatigue, and ability to work in gravity-minimized and gravity-influenced positions. Attention to these features will help ensure the success of the seating intervention. Appendix 32.A provides an overview of features of the wheelchair postural support system.

Seat Support

The seat support is the surface under the buttocks and thighs. A firm seat support is critical in creating good LE alignment, good pressure distribution, and improved comfort. Many basic manual wheelchairs come with sling upholstery. Over time, this type of surface creates poor pelvic positioning (Fig. 32.18). The hips tend to slide forward and the thighs tend to shift into hip adduction and internal rotation. Sling upholstery is used to increase the ease of folding the wheelchair. However, if the system is needed for more than transportation, a firm seat support should be added to the wheelchair. A solid seat board can be placed under the cover of a seat cushion to provide the firm base of support or a special seat pan (solid seat of metal or plastic that mounts directly to the seat frame or with attaching hardware to seat frame) can be added to the wheelchair once the upholstery is removed (Fig. 32.19).

Different seat supports have different properties. Foam, air, gel, combination types, and custom-shaped cushions are used to promote improved positioning, improved stability for UE activities, improved pressure relief, and improved comfort.²⁴ The person should test various seat cushions to determine what system is optimal.

Properties of the seat that need to be considered include the surface shape, firmness, flexibility, dimensions, placement, and attachment features. The most critical dimensions include the seat depth and seat width. If the seat depth is too long, it promotes a posterior pelvic tilt and kyphotic spine posture. If the seat width is too wide, it will make propelling the wheelchair more difficult and if too narrow, increase pressure on the hips from the armrests and footrest system.

Box 32.2 provides a list of questions that should be considered when finalizing the seat support.

Back Support

The back support is the surface behind the trunk. A firm back support is critical to promote good trunk posture and, in conjunction with lateral trunk supports, contributes to maintaining midline posture. Many basic manual wheelchairs have sling upholstery and this promotes poor trunk posture. There is an increased risk of a kyphotic spine and posterior pelvic tilt. The back support height can be varied depending on the needs of the individual. A shorter back may be appropriate for a person propelling the wheelchair with a taller back needed for a person who uses the tilt-in-space feature. A shorter back is more appropriate for a person with good trunk control and the ability to maintain good alignment without using lateral trunk supports. Back height is determined based on the person's trunk control, functional abilities, and comfort.

Different back supports have different properties. Foam, air, gel, combination types, and custom-shaped cushions are used to promote improved positioning, pressure relief, and comfort. The person should test various back cushions to determine what system is optimal.

Properties of the back that need to be considered include the surface shape, firmness and flexibility, dimensions, placement, and attachment features. The most critical dimensions include the back height and back width. Box 32.3 presents questions that should be considered when finalizing the back support.

In addition to the seat and back support, other supports might be necessary to ensure optimal positioning, pressure relief, and comfort, including lateral trunk and hip supports, lateral and medial knee supports, head and foot support, anterior chest and UE support, and pelvic support.²⁵ When determining the need for the support, consideration should be given to surface shape, firmness and flexibility, dimensions, placement, and type of attachment.

Pelvic Positioner

A belt or more rigid pelvic positioner may be needed to maintain good pelvic position (prevent the hips from sliding) and/or for safety.²⁶ The direction, angle of pull, and number of anchor points of the belt is important.²⁷

For example, if one hip tends to pull forward consistently, it may be useful to have the belt tighten by pulling it down toward that hip. The angle of pull to the seating surface should normally be 45° to 60° (Fig. 32.20).²⁶ Some patients respond well to belts that form a 90° angle with the sitting surface. This pull discourages patients who tend to extend in their wheelchairs as a result of increases in tone. This 90° placement also leaves the pelvis free for anterior tilting, an assist for those patients who can use this mobility for added function (Fig. 32.21). Some patients can benefit from multiple angles of pull. For these clients, a four-point belt might be most appropriate. A four-point belt provides four places to anchor the belt. The top two anchors assist in pulling the pelvis back against the back support and the bottom two anchors assist in preventing the pelvis from shifting forward and up. Other pelvic positioners are available as discussed in Seating Principle 2: Achieve and Maintain Pelvic Alignment.

Upper Extremity Supports

Wheelchair armrests have many important functions. They provide a support surface for arms as well as a surface for pushing up to standing and a mechanism for ischial pressure relief (sitting pushups). The armrests are also used to support trays for UE support or communication devices. The height, length, and width of the armrests are important measurements to ensure independence and comfort. If the armrests are too high, undue stress can be placed on the shoulders and if too low, slumping to reach the support frequently occurs. If the armrests are too wide, it may interfere with lifting the armrest for transfers or affect the ability to propel the wheelchair. If too narrow, the arms may slip off rendering the armrests ineffective in assisting with trunk posture.

For some individuals, the armrests will be used to mount an upper extremity support surface (UESS) such as a tray or trough. These surfaces provide several important functions. They can be used to achieve symmetrical positioning of the UEs, maintain corrected alignment of the glenohumeral joint and scapula, and serve as a work or communication surface. They also can act as an adjunct to the postural control system by supporting the weight of the upper limbs and decreasing pull on the shoulders and trunk.

Lower Extremity Supports

Style and position are important considerations when selecting foot support systems. Placement of the foot support system will directly affect the position of the entire lower body, affecting tone and posture in the trunk, head, and arms. Adequate hip flexion will help keep the pelvis well positioned on the sitting surface. Appropriate foot support height and style are required for maintenance of this position. Foot supports that are too low will result in lower knees, placing the hips in a more open angle and encouraging forward sliding of the pelvis. Foot supports that are too high may unload the thighs, placing increased weight on the ischial tuberosities. Elevating leg rests even in their lowered position may place excessive stretch on tight hamstrings, pulling the pelvis into a posterior tilt (Fig. 32.22). Any limitation of motion imposed by the hamstrings will directly influence the choice of foot positioners. To achieve maximum comfortable hip flexion, it may be necessary to flex the knees more than 90°, requiring special intervention on the foot supports. Decisions regarding straps and foot positioners must be made early, based on available ROM, to ensure caster (front wheel) clearance on the final unit.

Secondary Support Surfaces

Other supports may be needed to improve trunk alignment, LE alignment, and head position. These supports are added to the main support surfaces and include, but are not limited to, lateral trunk supports, medial and lateral knee supports, lateral thigh supports, headrest, and anterior chest supports. When determining the need for these supports, a specific goal should be identified to justify each item.

The Wheeled Mobility Base

The wheeled base forms the mobility structure for the seating system. Mobility bases include manual systems and power systems. Manual systems can be set up for independent use where the user is able to propel the wheelchair or dependent use where a caregiver moves the chair.

Manual Mobility Systems

Dependent manual systems include strollers, pushchairs, and some manual wheelchairs. These systems typically have small wheels that are not intended for self-propulsion. They may also be set up for increased ease of folding for transportation.

Four different methods of self-propulsion are available in the independent manual mobility category. Independent manual propulsion using both hands is indicated for those with good UE function and strength and is the most common. This system is usually set up with large rear wheels. However, the large wheels can be positioned in the center of the base (mainly used with children) or in the front of the base (Fig. 32.23). Positioning the wheels in different configurations can improve the ability to reach and propel the wheelchair. This is especially critical when considering the possible implications for long-term function of the shoulder girdle.

Research indicates that patients who use manual wheelchairs, especially if they are not properly fitted to their bodies and functional level, are in danger of UE damage from repetitive strain injuries (RSIs). Repetitive strain injuries can result in damage to soft tissue (tendons, ligaments, nerves) or bony structures secondary to frequent repeated motions such as wheelchair push strokes. The damage can include inflammation, compression, and/or tears in the shoulder joint and surrounding structures, resulting in pain and decreased function.^28,29

Repetitive strain injuries have been identified in the shoulders, wrists, and hands of wheelchair users. Even patients without documented RSI report increased pain in these joints with prolonged wheelchair use.^30,31 Small muscles are required to produce large forces repeatedly to move the chair through space. These same muscles are typically required for a variety of activities of daily living (ADL) tasks, thus increasing the demands placed on the same muscles with the potential of causing trauma. Muscles are used in atypical positions, and become overstretched and overused. Stress on the muscles and joints increases with increased wheelchair weight, increased user weight, and environmental factors. Many symptoms are not felt until the condition is well advanced. Rotator cuff injuries and instability of the glenohumeral joint are common at the shoulder. Since a number of muscles cross the wrist and elbow, problems occurring at the wrist often create pain at the elbow. Medial epicondylitis and carpal tunnel syndrome (CTS) are common. See Box 32.4 Evidence Summary for a summary of studies addressing UE pain associated with wheelchair propulsion.

When prescribing wheelchairs and features for patients who are able to self-propel, consideration must be given to preventing RSI whenever possible. An important prevention strategy is careful positioning of the UE to allow the most efficient stroke during propulsion, reducing the amount of force needed per stroke and reducing the number of strokes required to move the chair. It is also critical to observe wrist alignment and make any needed recommendations to minimize trauma and the chance of impingement leading to CTS.^32,33,34 Other criteria that should be considered in prescribing a self-propelled wheelchair include selecting a chair that

• Has the lightest weight possible

• Has a stable frame for most efficient movement

• Is well manufactured, with high-quality bearings (increased ease of motion for moving parts) for less roll resistance when push forces are applied, and secure nonmoving parts

• Provides optimal wheel size and type consistent with patient size and function

• Provides the best possible combination for ease of propulsion and stability

Many features must be considered when determining the optimal manual wheelchair setup for a person who is able to self-propel. Many bases are available, each with small differences that can increase or decrease the person's functional skills A rigid frame is lighter weight than a folding frame but may be more difficult to transport for some individuals. The ability to adjust the front and rear seat height by changing casters, fork lengths, and rear wheel size can assist a person with balance issues. The ability to change the seat back angle and the frame angle can assist a person with postural issues.

The second method of self-propulsion is using a one-arm drive system. This is appropriate for a person who is only able to functionally use one UE. In this case, there are two rims on the side being used to propel the wheelchair. The outer rim enables the chair to turn in one direction, the inner rim to turn in the other direction, and engaging both rims enables the chair to move forward (Fig. 32.24).

The third method of self-propulsion is using one or both feet. When using this method, care should be taken to ensure that the seat is low enough to the floor so the person continues to have good positioning and does not risk sliding out of the wheelchair.

The final method that can be used for self-propulsion is a combination of one arm and one leg. In this case, care must be taken to have the seat low enough to the floor, as well as have the rear wheel an appropriate size and position to use for functional mobility.

Power Mobility Systems

A power mobility system (Fig. 32.25) consists of a base or frame, a seating system, and electronics (batteries, motors, control module, and driver control).

If a person is unable to mobilize a manual wheelchair and is cognitively aware of surroundings, power mobility should be considered.^35,36,37,38 It should also be considered for wheelchair riders who are marginal self-propellers in manual wheelchairs. They may be able to move around indoors, and on level surfaces outdoors, but cannot move around in the community environment without unduly stressing muscles and joints, creating postural problems, and/or imposing cardiovascular strain. Long-term overuse injury of muscles and joints and the possibility of skeletal deformity must be discussed with the patient and caregiver as part of the examination process. Patients must face the possibility that injury may create problems significant enough to impede function in critical areas such as transfers and ADL.^{28,29,30,31,32,33,34,39,40,41,42,43}

An examination of the patient's full environment must be made to determine if power mobility will be helpful and usable (see Chapter 9, Examination of the Environment). Architectural barriers such as steps might preclude the use of power mobility or require that the patient have both a power and manual system for use at different times. In addition, attention should be given to how the chair will be transported, and the level of technology tolerance of both the consumer and caregiver. For patients whose condition is changing, a long-term plan must be established to guide decision making when choosing products. When considering power mobility for individuals who may have cognitive impairments, the rule of thumb is that the driver is aware of safety for himself or herself and others. In most cases, the ability to stop and to judge when to stop is more difficult to teach than driving itself. Awareness, reliable movement, motivation, and good response time are all important factors in wheelchair use.

Control Options

A variety of control options are available for powered mobility, including hand control, head array systems, sip 'n' puff breath control system, single switch systems, and scanning array systems.

Hand Controls

The most efficient method for driving a power wheelchair is with a hand. Joystick controls are used to control the direction and speed of the wheelchair. The final placement of the joystick is important to ensure that the person can reach the control without difficulty and without putting excessive stress on the wrist, elbow, or shoulder. Access to on/off switch, mode switch, and/or speed dial must be assessed to ensure independent control and prevent accidental hitting when driving.

Head Array Systems

Some individuals are unable to use their hand to mobilize the wheelchair but have good head control. A head array system can be used for driving. A simple system consists of three switches. The switch behind the head allows the chair to move forward, the one to the left side of the head turns the chair left, and the one to the right side of the head turns the chair to the right. Hitting a combination of the switches allows the user to maneuver the chair with increased ease. A fourth switch can be used for reverse or to toggle the system so the rear pad on the head array becomes reverse. This fourth switch can also be used to change the speeds and operate other wheelchair functions. Good head control is needed to operate this type of system.

Sip 'n' Puff System/Breath Control System

The sip 'n' puff system is used with breath control. A straw is used in the mouth. A hard puff allows the chair to move forward, a hard sip for reverse, a soft puff is right, and a soft sip is left. The air control is from the mouth rather than from the lungs. Systems can be calibrated for easier or harder puffs and sips. The system can be set up in latch mode (forward is locked after a hard puff) so the person is not required to constantly be puffing into the straw to keep the chair moving forward. Once in latch mode, small puffs or sips provide steer correction. A hard sip stops the chair. When using this type of system, it is important to have good lip closure without leakage through the mouth or nose for optimal efficiency. A combination of sip 'n' puff and switches can be used for driving a wheelchair if a person has difficulty differentiating the hard and soft puffs and sips.

Single Switch Systems

A variety of single switches can be set up for driving a power wheelchair. If a person is unable to use a head array or sip 'n' puff system, single switches can be set up at any area with even minimal active movement (e.g., hand, elbow, head, chin, knee, foot, and so forth) to control the wheelchair. A tray can be used with good gross movement of the UE to activate a series of switches with each one assigned a different function. The switches can be different styles, sizes, and colors to differentiate function. Four switch placements are needed to operate a wheelchair using this method.

Scanning Array System

A scanning array is available for a person who only has one switch placement site available. A light scans around a display highlighting different directions. When the light hits the direction of travel, activation of the switch moves the chair in that direction. Once the contact is removed from the switch, the scanner light continues to move around the display in a preset fashion. Although this type of system can be slow and tedious, the ability to drive independently is extremely rewarding for the motivated person.

Other Systems

Foot, arm, and chin control systems are available for driving a power wheelchair. A variety of switch options are available that include proximity switches, zero touch switches, and infrared switches for driving a power wheelchair. Testing of the recommended equipment is essential to ensure that the person can drive safely and efficiently both indoors and outdoors.

Power Wheelchair Bases

Four types of power wheelchair bases are available for mobility, and each system has its own set of benefits. Every person is different and many people can only drive one type of power base. Testing is needed for both new users and experienced users who may want to change the type of chair they have been driving.

Scooters

This style chair can be three or four wheeled and operates with a hand control lever system (see Chapter 9, Examination of the Environment). The seat options tend to be limited in sizes and supports. Many individuals like scooters for the ability to maneuver in small places, the ability to rotate the seat for transfers, and in some cases, the ability to elevate the seat for improved reach. These can be easier to disassemble for transport but might not have the power or electronic capabilities needed for driving outdoors. Although scooters tend to be less costly, consideration of a person's disability, changing needs, and environmental issues need to discussed before moving forward with purchasing a scooter.

Rear Wheel Drive Bases

A rear wheel drive wheelchair has the fixed drive wheels in the rear of the chair and the casters are in the front. Individuals driving this type of base see exactly where they are going and are able to watch their feet to ensure they do not hit walls, doors, or other items. Until recently, this was the most commonly used wheel drive base. With improved technology, center wheel drive bases are now the most commonly used base system.

Center Wheel Drive Bases

A center wheel drive wheelchair has the fixed drive wheels in the center of the chair and small casters both in front and in the rear of the chair. The chair turns from the center and care must be taken when turning to know what is behind and in front of the chair. Better LE positioning can be attained owing to improved caster clearance.

Front Wheel Drive Bases

A front wheel drive wheelchair has the fixed drive wheels in the front of the chair and the casters are in the rear.

When turning the chair, the back end moves first and care must be taken to ensure sufficient posterior clearance. This type of chair allows closer proximity to tables or sinks. Lower extremity positioning is improved with no caster clearance issues.

Seating System Features

Adjustable Tilt-in-Space Seating Systems

Manual and power wheelchairs can have an adjustable tilt-in-space feature. The tilt-in-space feature is a seating system with a fixed seat to back support angle, fixed seat to lower leg support angle, and fixed lower leg to foot support angle that can be adjusted to tilt rearward or upright depending on the needs of the person (Fig. 32.26). In a manual wheelchair, in most cases, a caregiver needs to change the tilt position. In a power wheelchair, the person can independently adjust the seat tilt with switch access. The tilt feature is beneficial for individuals who have fair to poor trunk control and are unable to sit up straight against gravity for the full day. The tilt provides them with a resting and repositioning position. The tilt also assists with positioning a person in the wheelchair after transfers. The tilt feature can assist in improving balance and head positioning, improving skin integrity by assisting with shifting pressure from buttocks to back, and improving comfort.^44,45

Adjustable Recline System and Elevating Leg Rest System

Both manual and power wheelchairs can have an adjustable backrest system and an adjustable leg rest system. This allows the person to recline in the wheelchair. This can assist with pressure relief and pressure distribution, bowel and bladder care, orthostatic hypertension, comfort, and ROM.⁴⁴ Each of these features can be ordered separately. On a manual wheelchair, a caregiver must adjust the recline and leg rest features. On a power wheelchair, the person can use power recline and power elevating leg rests independently with switch access. If manual elevating leg rests are obtained, the person will be dependent for leg positioning. Care must be taken when determining the need for both these features. In most cases, elevating the leg rests does not decrease edema; the legs need to be raised above the heart to achieve this effect. Hamstring muscle tightness needs to be examined to determine if appropriate sitting posture can be maintained with the legs elevated. Too often, extending the knees causes sliding of the pelvis on the seat surface. This increases the potential of pressure sores under the buttocks and promotes poor trunk posture. If increased muscle tone is present in the LEs, knee extension may cause spasms and pull the knee into flexion, often causing the leg to slip off the elevating leg rests and potentially causing injuries. The recline feature also needs to be examined carefully to ensure that the change in back position does not increase the potential for sliding down in the wheelchair.

Power Seat Elevator

A power seating system may include a power seat elevator feature. This feature allows the seat to be raised or lowered to accommodate for height differences and improve reach. This can improve access to tables, sinks, cabinets, and so forth. The feature can also increase ease for transfers on and off the toilet and bed. In the raised position, it can also provide improved social interaction. The power wheelchair can be driven using this feature, but the speed of the chair is slowed for safety concerns.

Standers

A stander is a device that allows a person to come to standing who ordinarily would be unable to stand without support. The stander can be a stand-alone device with or without wheels. For a person who would like to stand throughout the day without transferring to a different device, a stander is available in a manual wheelchair and a power wheelchair. In the manual wheelchair, the system is set up to raise and lower the person using his or her own arm strength. The added stander portion increases the weight of the chair but allows changing position throughout the day as needed to stand, stretch, reach, and work. In the power system, a switch is used to activate the stander and the same benefits achieved with a manual system can be achieved in the power system.

Power Assist Wheels

Power assist wheels are attached to a manual wheelchair. This provides the person with an assist on each propulsion.^46,47,48,49 It increases the ease of pushing a manual wheelchair both indoors and outdoors. This can assist a person who prefers to use a manual wheelchair rather than shifting to a power wheelchair.

Specific Wheelchair Frame Features

Sling Back and Sling Seat Upholstery

Sling back and seat upholstery are standard items on basic manual wheelchairs. This is convenient when a person needs to fold the wheelchair for car transportation. However, sling upholstery can promote poor sitting posture, posterior pelvic tilt, hyperextended neck, and poor LE positioning. The sling upholstery should only be used when the chair is primarily being used for transportation, if the person will only be using it for short periods of time, if the person is able to reposition himself or herself and is not at risk for developing contractures, and if the system needs to be as light as possible for mobility. Sling back upholstery is a standard item on basic power wheelchairs. Caution should be used when recommending this type of back due to the potential for poor trunk posture, increased kyphosis, and increased hyperextended neck posture. If at all possible, sling upholstery should be avoided due to potential for development of poor posture and increased health problems. Firm back and seat supports can be added to the wheelchair and removed for transportation purposes. Figure 32.27 provides an overview of the foundational components of a prescriptive wheelchair.

Back Angle Adjustment

The back angle adjustment is available on some basic manual and power wheelchairs and most tilt-in-space seating systems. The back posts can be angled and bolted in a specific position. Depending on the wheelchair manufacturer and the wheelchair style, various amounts of back angle are available. Some chairs only have 10^° of adjustment while others have 30^° of adjustment. This feature is beneficial for a person with limited hip flexion, as well as a person who needs a fixed rearward tilt position who does not want a tilt-in-space seating system.

Seat Frame Angle and Height

The manufacturer of manual wheelchairs sets the seat frame angle and height. Some wheelchairs are available with adjustable axle plates and adjustable forks. This provides the ability to alter the wheel size, caster size, and wheel placement to achieve a specific height and specific frame angle (Fig. 32.28). This can help a person with hamstring tightness by improving clearance for feet or assist a person with difficulty sitting upright to be tilted rearward slightly for improved posture and UE control. This can also assist a person with reaching the floor for propulsion using the feet or improve the ease for performing transfers.

Footrest System

The footrest system is made up of hangers, extensions, and footplates. The hangers mount to the wheelchair, and the extensions provide the appropriate length for the calf and footplate support. The hangers swing out of the way for transfers. If transferring independently, practice trials using the release mechanism will ensure patient skill and safety in their operation. The footplates can be fixed or adjustable. The adjustable footplates (footplate can be moved and, depending on placement and angle, affects the foot and knee position) allow optimal positioning of the foot when tightness is present at the knees (seat to lower leg support angle) or foot (lower leg to foot support angle). This provides increased flexibility for positioning, especially if a person has changing needs.

Armrest System

Armrests come in desk length or full-length styles. They can be fixed height or adjustable height. There are a variety of methods to move the armrests out of the way for access to tables and for transfers. The person's functional skills will determine what system is optimal for independence.

Wheel Options

Rear wheel options on a manual wheelchair are important to ensure independent propulsion. If wheels are too large, excess strain can be put on the shoulders. If wheels are too small, they may be difficult to reach and propel. The type of wheel is important depending on the types of terrain the person will be using. Knobby tires may assist in rough terrain. A variety of wheel rims are available. Aluminum rims can be coated, have projections, or be a smaller size depending on method used for pushing.

Caster size options are numerous. A larger caster (8 in) may interfere with foot clearance depending on positioning needs. A smaller caster may provide improved positioning of feet and greater ease turning the wheelchair. Larger casters may improve ease of traveling over potholes or grates.

Options on a power wheelchair are more limited depending on the style of the wheelchair, but the tires tend to be wider for better traction. More options are available for casters on a rear wheel drive wheelchair and some prefer a larger front caster for improved driving on uneven terrain.

Seat Width and Depth

Manual and power wheelchairs come in a variety of widths and depths. If providing a person with a manual wheelchair, it is important to make sure the chair is not too wide or too narrow since this will affect the ability to propel the wheelchair (Figs. 32.29 and 32.30). Testing of the various chair widths is important to ensure that the shoulders are protected from excessive strain. The seat depth is important to ensure that optimal positioning can be achieved with seating supports.

Power wheelchairs and tilt-in-space seating systems may be available with adjustable seat widths and depths. This feature allows fine-tuning adjustments and attaining optimal sitting posture over time. Often, a range is provided for the adjustable seat width. Care should be taken to choose the most optimal range. For instance, if a width of 20 in (50.8 cm) is needed, a frame may be selected that can be adjusted from 16 to 20 in (40.6 to 50.8 cm) or 20 to 24 in (50.8 to 60.9 cm). If the patient is unlikely to gain weight, the smaller size should be chosen; if the potential for weight gain is evident, the larger size should be chosen. The newer power wheelchairs tend to have more seat depth adjustability, but again, care should be taken with the base length of the chair to make sure it will not be too long for maneuvering safely indoors.

Many users are active in recreational and competitive sports, some of which are done from the wheelchair. These patients may need more than one wheelchair: a street or everyday chair, and a finely tuned competition chair or recreational chair (Figs. 32.31,32.32,32.33,32.34,32.35,32.36,32.37). For some sports such as archery, discus, shot put, and precision javelin, a more stable chair is an advantage. A wide wheel camber (angle of the wheel, top of the wheel is closer to the user and the bottom of the wheel is further away to provide a more stable system) (Fig. 32.31) can achieve this even on a lightweight frame. For basketball, tennis, and dancing, the chair's responsiveness is critical. Competition chairs are usually of rigid construction, and made of very strong lightweight materials. Wheel and caster placement, tires, axles, and bearings can make a radical difference in chair performance when matched with the user's body weight and configuration. Users who participate in more than one activity may want a chair with a great deal of adjustability to allow parameter changes for various activities or multiple chairs, if possible.

Individuals who use their wheelchairs on off-road, challenging trails will require knobby tires (see Fig. 32.28), because the tread of normal wheelchair tires will tend to get stuck in softer ground. Those who compete in road racing will need competition chairs that have taken many of their design features from racing bicycles: narrow, hard tires; frames made of lightweight alloys, titanium, or carbon; low seats for minimum air resistance; and small push rims for higher gearing. Racers usually sit in a tucked position, with approximately 120° of hip flexion, knees flexed, and legs strapped together to present a very sleek line and minimal wind resistance as the unit (wheelchair and user) moves quickly along the track. For tennis and dance, the chair is trimmed down to its sleekest configuration with all accessories, even wheel locks, removed. Wheel hubs and spoke configurations are designed to hold a tennis ball during competition. The backs are as low as possible to leave the user's upper body free for movement (see Fig. 32.31).

Many individuals using a wheelchair for the first time will require a training period. During this time the individual will learn how to propel the chair in all directions (i.e., using both arms, one or two arms in combination with one or two legs, or one arm using a dual-wheel drive system). He or she must also learn how to operate the wheel locks, foot supports, and armrests, and to use the mechanisms safely without tipping forward or sideways out of the chair seat. He or she will learn how to transfer in and out of the chair with the least possible assistance. Some users will always require maximal assistance for transfer activities, but others will be able to achieve functional independence. Chair features such as removable or swing-away arm and foot supports and lowered seat heights may be important for independence. For patients who perform standing transfers (independent or assisted), special attention should be given to the user's ability to get out of or back into the chair, because the seat height may prove problematic. Most chairs with a cushion allow a user to slide forward and come to standing. Many patients may benefit from adjustable height armrests. In addition to adjusting for arm support needs, these armrests can be raised during sit-to-stand transfers.

Although sidewalk cutouts are now mandated in many areas, patients who are capable of independent community mobility benefit from learning to do wheelies to negotiate existing curbs. The chair is balanced on the rear wheels while the front casters are elevated and then propelled forward to mount the curb.

Patients who drive need to practice transfers from the wheelchair to the car seat. The wheelchair is then pulled into the vehicle either behind the seat, or across the person's body into the passenger seat. Alternatively, the individual may transfer into the front passenger seat and then pull the wheelchair into the vehicle. The method selected is very dependent on the chair's folded size and weight, the user's upper body skill and strength, and the internal configuration of the car. Active patients also need to practice controlled falls out of the wheelchair and floor-to-wheelchair transfers that can be utilized in the event of falls.

Power chair training is slightly different, and usually concentrates primarily on driving skill and safety. The initial challenge is to locate a reliable access control site and method (e.g., hand control with a joystick, head control with individual switches). Training then involves working with the user on consistent responses (especially to "stop" commands, or the recognized need to stop based on the user's awareness) and accurate maneuverability. Although switch activation can be judged using a computer program, actual road time is necessary for training and ensuring that the driver knows how to respond to a variety of situations, distractions, and obstacles.

It is also important for wheelchair users to learn how to ask for help and how to direct helpers who might be touching them or the wheelchair. Some rehabilitation facilities have large fleets of sample chairs that can be used with patients for examination and training. If this option is not available, a qualified supplier or manufacturer's representative in the area should be contacted.

Traditional home care and/or durable medical equipment companies are qualified to accept basic prescriptive wheelchair information (basic manual wheelchairs only) over the phone. They keep standard-sized items in stock, and can get them to the user quickly, often within 24 hours. More specialized equipment usually requires input to the team from an Assistive Technology Professional (ATP) who has passed the Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) national certification examination or a Certified Rehabilitation Technology Supplier (CRTS) who is a member of the National Registry of Rehabilitation Technology Suppliers (NRRTS) and is also an ATP. He or she is a specialist in the field of complex rehabilitation technology service delivery and can work with the team to design a system that fits the patient's unique needs. Once the team's goals are explained to the supplier, he or she will be able to provide a list of available products that match the user's needs. It is critical that the team hear about all of the options, not just the products available from one manufacturer. The CRTS or ATP will be able to explain the pros and cons, as well as the prices of various products and options, to everyone involved. It may be advisable for the user to actually try several products before a decision is made. The supplier can work with the team to arrange this opportunity.

Once a system has been selected, the clinical team's recommendations (including physical, psychosocial, and cognitive factors if applicable) are compiled into a letter of medical necessity. The letter of medical necessity (with physician and clinic team member signatures), a physician's prescription, and price estimate are then forwarded to the third-party payer(s). The justification package should explain the medical need for each feature requested, along with the anticipated goal the feature will accomplish, and expected outcome from the intervention. Providing measurable functional outcomes is essential to help the payer make an informed decision.

The CRTS or ATP should keep all of the team members apprised as the process moves along from submission through approval, ordering, and receipt of the chair and its components. Once the system is complete, the supplier must deliver it as instructed by the prescriber (to the clinic, school, or home of the user). At delivery, those involved with formulating the prescription should have an opportunity to inspect the system and be sure that it meets the specifications, as well as to observe and assist as the supplier makes final adjustments. The process may require more than one or two visits for complex systems that require interim fittings.

On final delivery, the CRTS or ATP explains to the user and/or caregivers how to use the chair, including use of all safety features (straps, wheel locks, anti-tipping devices), assembly and disassembly for folding, and normal maintenance (including battery maintenance on power wheelchairs and scooters). Once the chair is delivered, the user and/or caregivers should carefully read any manuals provided and mail in all warranty and registration materials. The user and/or caregivers are responsible for all normal cleaning and maintenance. The supplier and the company he or she works for should be located close enough to the user to provide emergency repairs as needed. Warranty repairs are the responsibility of the supplier who provided the chair (most warranties cover the cost of labor for 12 months following purchase and then labor costs become the responsibility of the owner).

A systematic approach to prescribing a wheelchair has been presented. The individual components of both the postural support and the wheeled mobility base have been described. The primary outcome in developing any prescriptive wheelchair is maximum function and independence. It must be the result of a thorough evaluation using a patient-centered problem solving approach, with attention to the specific factors discussed in this chapter. Input from the user and all team members during the decision making phase is critical. This process will result in an optimally designed chair capable of achieving its intended purpose. Using a patient-centered approach with open communication among team members, rehabilitation technology supplier, and manufacturer will ensure that each prescriptive wheelchair will meet the needs of the individual.

1. Explain what information or data are gathered during each of the following portions of the examination process:

   1. Background information

   2. Examination of function using existing equipment

   3. Examination in the supine position

   4. Examination in the seated position

2. Discuss the importance of using seating principles when performing seating assessments.

3. Explain the difference between range of motion for a seating assessment and range of motion for a standard physical therapy examination.

4. When determining seat to back support angle, what parameters are used to finalize this angle?

5. What techniques should be used when measuring seat depth?

6. Why should recommended equipment be tested by the intended user? What specific issues need to be tested?

7. When would you recommend a wheelchair with sling seat and back upholstery?

8. When would you recommend the following types of cushions?

   1. Firm seat cushion

   2. Contoured seat cushion

   3. Air seat cushion

   4. Custom-molded seat cushion

9. Why is a pelvic positioner important and what methods can be used to make it more effective?

10. Describe the following wheelchair components; compare and contrast their functional benefits:

    1. Detachable swing-away footrests versus elevating leg rests

    2. Fixed-height armrests versus adjustable-height armrests

    3. Single-axle placement versus multiple-axle placement

    4. Proportional drive versus micro-switch driving

11. Identify four methods of self-propulsion in manual mobility and the benefits of each method.

12. Explain the benefits and contraindications of power mobility.

13. Identify four methods for driving a power wheelchair and discuss the clinical presentation of the patient who will benefit from each system.

14. Describe the various power wheelchair bases available and the benefits of each system.

15. Discuss the pros and cons of a tilt-in-space system versus a recline system with elevating leg rests.

Patient is a 56-year-old male with a diagnosis of multiple sclerosis. He currently uses a scooter for mobility and complains of seat discomfort and difficulty getting under tables. He resides in a long-term care facility.

Patient sits in a posterior pelvic tilt with a kyphotic spine in his scooter. He tends to lean to the left side. His hips and knees are in increased flexion due to the seat height being too low. Patient stabilizes himself in the scooter by maintaining his hands on the scooter handles at all times.

Patient is able to drive the scooter safely and independently. He is able to perform his ADL while using the scooter.

Patient has minimal range of motion limitations that affect his seating when assessed in the supine position. Hip flexion is 0 to 80° bilaterally. He lacks 90° of knee extension when hip is flexed to 80° bilaterally. Ankle dorsiflexion is neutral bilaterally when knee is flexed to 90°. Pelvic movement is flexible. Trunk posture is good but patient has the tendency to lean his shoulders to the left side with a shift of his trunk to the right side. Increased tone noted in both lower extremities. Patient has a stage II pressure sore on his right ischial tuberosity.

Patient was positioned in a seating simulation chair. Improved posture noted in trunk and pelvis in comparison to position in scooter. He preferred to be tilted rearward slightly and noted that this position assisted with his balance. The change in posture was significant and he will need a trial with this posture to ensure ability to perform ADL and improve his comfort with postural alignment changes.

Goals for patient include the following:

• Improve sitting posture and comfort

• Improve skin integrity

• Improve access to sink and tables for functional activities

• Improve independence in mobility in facility and out in community

1. What type of power wheelchair would you have this patient test?

2. What type of electronics should be considered?

3. Based on range of motion limitations, what are the concerns for a seating system?

4. What type of seat cushion would you recommend?

5. What type of back cushion would you recommend?

6. Fill out a problem solving grid and address issues of posture, skin integrity, health/medical issues, functional tasks and abilities, environmental issues, caregiver needs, social and emotional issues, and mobility issues. Use the following four column headings in developing the grid: Problems and Potential Problems, Objectives, Properties, and Product.