Wheelchair Fitting

Original Editor - Simisola Ajeyalemi as part of the Wheelchair Service Provision Content Development Project

Top Contributors - Naomi O'Reilly, Simisola Ajeyalemi, Kim Jackson, Stacy Schiurring, Tarina van der Stockt, Shaimaa Eldib, Rucha Gadgil, Amrita Patro, Olajumoke Ogunleye and Robin Tacchetti  

Introduction

Wheelchair fitting is the second step in the WHO's four-step wheelchair service delivery model, which includes Select, Fit, Train, and Follow Up. This streamlined approach, introduced in the 2023 WHO Wheelchair Provision Guidelines, consolidates the previous eight-step model to ensure greater relevance across all settings and populations. The guidelines emphasise that optimal outcomes in wheelchair access occur when wheelchair users benefit from an individualised process of assessment, fitting, training, and follow-up, provided by trained personnel.

The fitting step involves trialing the wheelchair with the user and making final adjustments to ensure the wheelchair is correctly assembled and configured. During fitting, wheelchair service personnel and the wheelchair user together verify that the wheelchair is the appropriate size, that all necessary modifications have been completed, that the wheelchair and cushion support the user in an upright sitting position, and that any needed pressure relief cushions effectively reduce pressure on at-risk tissues. Proper wheelchair fitting is essential for optimising function, preventing secondary complications, and supporting the user's participation in daily activities.

Research indicates that 80-90% of individuals are not properly fitted in their current wheelchair as their bodies and needs change over time. A poorly fitted wheelchair may contribute to pressure injuries, compromised posture, reduced balance, difficulty with propulsion, and challenges during transfers. The importance of individualised fitting cannot be overstated, as each wheelchair user presents with unique physical characteristics, functional abilities, environmental considerations, and personal goals that must inform the fitting process.

Principles of Wheelchair Fitting

Contemporary wheelchair fitting practice has moved beyond rigid formulae towards individualised assessment that considers the whole person. While older guidelines often promoted standardised positioning rules current evidence challenges these prescriptive approaches, recognising that no two bodies are the same and that anyone requiring wheelchair seating may have diverse positioning needs including considerations for stability, function, and comfort.

Modern wheelchair fitting priorities:

Individualised Assessment. Each fitting must account for the user's unique body tolerances, range of motion, muscle tone, sensory status, functional goals, and environmental demands. A comprehensive physical assessment in both sitting and supine positions provides essential information about body alignment and positioning tolerances.

Functional Positioning. The primary physical priority of proper wheelchair fitting is to achieve functional upright postural alignment to maintain spinal health, improve breathing and swallowing, and prevent musculoskeletal issues. The optimal seated position is one that supports and maximises the user's functional activities, including propulsion, transfers, reaching, and engagement in activities of daily living (ADL's). For example, asymmetry may be appropriate when accommodating a user's natural postural alignment. The goal is not to "fix" every postural deviation but rather to provide stable, comfortable, functional positioning that mimics the individual's optimal alignment.

Pressure Management and Skin Integrity. For users at risk of pressure injury (particularly those with impaired sensation or limited mobility), pressure distribution across the seating surface is paramount. All wheelchair users should use a cushion, and those with limited or no skin sensation must use a pressure relief cushion to reduce the risk of pressure injuries. Positioning must be sustainable over time. If a position causes discomfort within 10-15 minutes, it is unlikely to be appropriate for extended wheelchair use. Tilt-in-space and recline features can also facilitate pressure relief and repositioning for users who spend extended periods seated.

Environment and Lifestyle Consideration. Wheelchair fittings should take into consideration how and where the wheelchair will be used. This includes indoor use (e.g. need for narrow frames and tight turning radii to navigate tight spaces), outdoor/varied terrain use(e.g. need for durability, larger wheel, and higher ground clearance), and transportability (e.g. lightweight materials and folding mechanisms).

Long-Term Health and Adaptability. Fittings should aim to slow or limit progression of postural changes and deformities, and accommodate potential changes in the user's condition or body composition over time. For example, incorporating adjustable components that allow the wheelchair to adapt to a user's evolving needs.

The Fitting Process

Wheelchair fitting should be conducted systematically, ideally by the same personnel who completed the initial assessment. The fitting begins once a person has been identified as needing a wheelchair and accesses wheelchair service, following the selection step. For wheelchair users requiring additional postural support, fitting may take longer and necessitate multiple trials. The fitting must be evaluated both when the wheelchair is stationary and during movement, whether self-propelled or attendant-propelled.

The recommended fitting sequence is:

1. Check Size and Adjustments
2. Check Posture
3. Check Pressure Distribution
4. Check Fit During Movement

Check Size and Adjustments

Seat Width. The seat should fit snugly without creating pressure on the lateral thighs. A practical assessment involves sliding fingers between the outside of the user's thighs and the wheelchair sides; fingers should fit comfortably without pinching. This is particularly critical for users with impaired sensation, as sustained pressure from the wheelchair sides can cause pressure injuries. Excessive width compromises lateral stability and may make push rims difficult to reach, potentially causing shoulder injury from overreaching. Seat Depth: Appropriate seat depth provides adequate thigh support while avoiding pressure on the popliteal fossa (back of the knee). Traditional teaching suggested subtracting 2-3 inches (5-7.5 cm) from the measurement between the popliteal crease and back of buttocks, but contemporary practice questions this prescriptive approach. The assessment should involve checking that the user sits upright with the back of the pelvis against the backrest, then evaluating whether there is appropriate clearance at the popliteal fossa (typically 2-3 fingers' width or approximately 30-60 mm) without pressure on the posterior calf. Both sides must be checked, as individual variations are common. Some users may require modifications to seat depth based on functional considerations, such as the ability to perform side transfers.

Basic measurements: seat width (A); seat depth (B); seat height (C); armrest height (D); backrest height (E); footrest length (F).

Footrest Height: Footrests should be adjusted so that the thighs rest evenly on the cushion with no gaps, and the feet are fully supported on the footrests with even pressure distribution. Assessment involves sliding a hand between the thigh and cushion to ensure consistent pressure along the thigh length, and visually confirming foot support without gaps. Footrests that are too high create gaps under the thighs and increase pressure on the ischial tuberosities; footrests that are too low leave gaps under the feet and may cause the user to slide forward.

Backrest Height: Backrest height must balance postural support with freedom of movement required for the user's functional activities. The backrest should provide the support needed while allowing active users freedom to move their shoulders for propulsion. During assessment, personnel observe whether the trunk is balanced over the hips and confirm with the user that the backrest is comfortable and does not interfere with intended activities.

For users who are active, have good sitting balance, and will self-propel, a backrest providing support to the base of the ribcage typically allows adequate freedom of movement. For users who fatigue easily, have progressive conditions, or experience difficulty maintaining upright posture, a backrest extending to the inferior angle of the scapula (bottom of shoulder blades) provides additional support while still permitting some shoulder movement for propulsion.

Rear Wheel Position (for self-propulsion): The rear wheels should be positioned to optimise propulsion efficiency and wheelchair stability. When the user grips the push rims at the top of the wheels, the elbow should be bent at approximately 90 degrees. This position minimises strain on the upper extremity whilst allowing effective force application. Additionally, wheel position affects wheelchair stability: forward positioning suits active users seeking manoeuvrability, whilst posterior positioning enhances stability for users prioritising safety.

Seat Height (for foot propulsion): Users who propel with their feet require a seat height that allows the feet to rest flat on the floor whilst maintaining appropriate pelvic support against the backrest. If the seat height is too high and cannot be adjusted sufficiently, options include reducing cushion height or, with technical support, lowering the solid seat attachment point. When one foot is used for propulsion while the other rests on the footrest, pressure distribution under the ischial tuberosity on the footrest side must be carefully assessed.

Check Posture

Postural assessment should be conducted from both the side and front view to evaluate the user's sitting alignment. Observations include whether the user sits in an upright, stable position with the pelvis appropriately positioned and the trunk balanced over the hips. Contemporary seating practice emphasises that there is no single "correct" posture; rather, positioning should be individualised based on comprehensive assessment of the person's body tolerances in sitting and supine.

Some wheelchair users prefer to tuck their feet underneath them; if the wheelchair design accommodates this, and the user feels comfortable and balanced, this positioning may be acceptable. The goal is sustainable, functional positioning that the user can maintain comfortably.

Check Pressure Distribution

For every wheelchair user at risk of developing pressure injuries, particularly those with impaired sensation, limited mobility, or history of pressure injuries, pressure distribution under weight-bearing areas must be assessed. Evidence indicates that air-cell cushions provide optimal pressure relief and shear reduction, though individual assessment with consideration of stability, transfer ease, moisture control, and maintenance requirements is essential for appropriate cushion selection.

Research demonstrates that pressure-redistributing wheelchair cushions designed to maintain tissue integrity can reduce the incidence of sitting-induced pressure injuries. When a pressure relief cushion has been prescribed, the fitting must verify that the cushion is effectively reducing pressure on high-risk areas, including the ischial tuberosities, greater trochanters, coccyx, and sacrum.

In addition to cushion selection, wheelchair users should be taught pressure relief manoeuvres—such as forward and sideward leans—which, regardless of cushion type, result in significant reductions in interface pressure and increases in buttock blood flow. Positioning the wheelchair user in a manner that facilitates in-seat movement is an important component of pressure injury prevention.

Check Fit During Movement

The final component of fitting assesses how the wheelchair functions when the user is moving. If the user cannot independently propel the wheelchair, a family member or caregiver should push the wheelchair during this assessment. Key observations include:

• Backrest: Confirms adequate support whilst permitting necessary freedom of movement for propulsion
• Rear Wheel Position: Verifies positioning allows effective propulsion mechanics
• Seat Height and Depth: Ensures appropriate dimensions for the user's propulsion method (upper extremity or foot propulsion)
• Postural Supports: Confirms that any postural supports do not restrict safe, efficient wheelchair mobility
• Footrest Security: Verifies that the user's feet remain securely positioned on footrests during movement
• Overall Stability: Ensures that movement or propulsion does not cause the user to alter their posture or experience discomfort or instability

Wheelchair Fitting Checklist

A systematic approach ensures comprehensive evaluation:

☐ Wheelchair assembled and ready for fitting

☐ Size and adjustments checked (seat width, seat depth, footrest height, backrest height, wheel position, seat height as applicable)

☐ Posture assessed (side and front views, trunk balance, pelvic alignment)

☐ Pressure distribution evaluated (for at-risk users)

☐ Fit during movement confirmed (backrest support, wheel position, seat dimensions, postural supports, footrest security, stability)

☐ User and caregiver comfort and satisfaction confirmed

☐ Any modifications documented

Problem Solving Common Fitting Challenges

Wheelchair service personnel often encounter situations where available wheelchairs do not perfectly match the user's dimensions or postural needs. The following table provides evidence-informed strategies for addressing common fitting challenges. These solutions assume that the closest-size wheelchair has already been selected from available options. More complex modifications and postural support interventions are addressed in intermediate and advanced-level training.

Table 2.0: Problem Solving Common Wheelchair Fitting Challenges

Problem	Possible Solutions	Implementation Notes
Seat Depth Too Short (>100 mm shorter than required for adults)	Extend seat rails and replace upholstery (for folding-frame wheelchairs with dedicated seat rails not integral to frame) Replace upholstery with longer material (for rigid-frame wheelchairs where seat rail extends beyond seat) Add rigid board (wood, plastic, or other material that will not flex or crack) fixed to top of seat rails with appropriate cushion	Ensure new seat is strong enough for user's weight and does not flex or crack. When adding height with rigid seat plus cushion, recheck backrest and footrest heights. All rigid seats require a cushion.
Seat Depth Too Long	Shorten seat: Mark required depth, remove upholstery or rigid seat, shorten using industrial sewing machine (upholstered) or cutting tools (rigid), replace with smooth, splinter-free edges Shorten cushion to match new seat depth	Always cut cushion from the front to preserve pressure relief properties at posterior aspect. Ensure all edges are smooth and safe.
Footrest Height Too Low	Shorten footrest hanger (on most four-wheel wheelchairs, ensuring adjustment mechanism remains functional) Build up footrest height using wood or sturdy material	Ensure build-up does not interfere with footrest swing-away function for transfers. Verify footrests do not catch on ground.
Footrest Height Too High	Replace inner extension tube with longer tube of same diameter and strength Increase cushion height by adding firm material underneath (not soft foam, which compresses and feels unstable)	If footrests become too low and catch on ground after adjustment, wheelchair may not be suitable. When raising cushion, recheck backrest height and ensure no functional problems (e.g., fitting under tables).
Legs Roll Inwards or Outwards	Verify footrest height provides adequate support Ensure seat is properly tensioned (firm, not saggy, as sagging encourages inward leg rolling) Add wedges to cushion or provide contoured cushion with thigh support	Some contoured pressure relief cushions have a rise between thighs to maintain appropriate leg position, or "gutters" with raised edges to prevent outward rolling. These can be modified to increase support as needed.
Feet Slide Off Footrests	Verify footrest height provides adequate foot and thigh support Adjust footrest angle if possible to assist with foot retention Add strap at ankle level (behind legs if feet slide backwards; in front of legs if feet slide forwards)	Straps must be easy to remove independently. Verify user can reach and operate strap without assistance. Ensure strap placement maintains even pressure under foot.
Wheelchair Too Wide	Add foam inserts on each side of pelvis: Measure space between centrally positioned user (back against backrest) and armrest sides. Cut and upholster foam inserts to fill space. Attach to armrests or top of cushion. Inserts need only extend forward to user's trunk.	If wheelchair is excessively wide, user may have difficulty reaching push rims, which can cause shoulder injury from overreaching. Carefully consider whether wheelchair is safe before prescribing. Ensure cushion width matches seat width.

Conclusion

Wheelchair provision through a service model, which includes individualised fitting, ensures the wheelchair meets the specific needs of each user, resulting in positive outcomes. Effective wheelchair fitting requires systematic assessment, evidence-informed decision-making, attention to individual user characteristics and goals, and ongoing collaboration between wheelchair service personnel and wheelchair users. The fitting step, while focused on physical wheelchair configuration, must always be understood within the broader context of the four-step service model, with training and follow-up steps ensuring sustained, optimal wheelchair use.

Resources

Clinical Resources

• WHO Wheelchair Service Training Package - Basic level (available in Arabic, Chinese, English, French, Italian, Japanese, Khmer, Portuguese, Romanian, Spanish, Thai, Turkish, Ukrainian, and Vietnamese)
• WHO Wheelchair Service Training Package - Intermediate level (available in Chinese, English, French, Japanese, Korean, Romanian, and Spanish)

Additional Optional Reading

• Peterson A, Fraix MP, Agrawal DK. Preventing pressure injuries in individuals with impaired mobility: Best practices and future directions. Journal of surgery and research. 2025 Jul 8;8(3):319.
• RESNA Wheelchair Service Provision Guide (2011); includes practice wheelchair user fitting case studies

References