Viability of 3D printing for load-bearing wheelchair components: A progressive anti-tipper prototype

Abstract

Customized wheelchair components that are designed to fit the individual user and consider their preferences can greatly improve the user’s quality of life, but are often cost-prohibitive using traditional manufacturing methods. 3D printing technology is advancing rapidly and has been used to manufacture assistive devices, but there is limited research on whether these methods are viable for load-bearing structural components in wheelchairs. We designed a progressive anti-tipper, an anti-tipper that provides a spring-loaded response to backwards rotation of the wheelchair. This prototype avoids the hard impact of rigid anti-tippers, and also provides increased range of motion of up to 20° rearward tip, allowing the front casters to rise far enough to climb curbs. We 3D printed our prototype using four different 3D printing methods in five materials (PLA, ASA, Resin, Onyx (Nylon+carbon fiber composite), and stainless steel). We performed function tests, ISO 7176-8 strength tests, and UTM destructive tests. The Onyx and stainless steel 3D prints passed our function and strength requirements, indicating that 3D printed parts show potential for load bearing components in wheelchairs. Further fatigue, strength, and real-world use studies are warranted to explore the viability of this technology.

Keywords

wheelchair assistive technology 3D printing additive manufacturing anti-tipper stability strength ISO 7176

1. Introduction

Customized wheelchair components that are designed to fit the individual user and consider their preferences can improve community participation and enhance the user's quality of life.¹ However, manufacturing these customized components are often cost-prohibitive using traditional manufacturing methods. Wheelchair manufacturers sometimes only invest in the high cost of design and tooling for components that sell in sufficient volumes, which may result in poor fit for many users. 3D printing (additive manufacturing) technology has been advancing rapidly, with the costs for printers and materials reducing with greater adoption, and shows promise for the manufacture of low-volume customized assistive technology. 3D printing has been adopted for the manufacture of customized assistive devices such as prosthetics and orthotics.^2–7 However, there is only limited scientific research on the viability of 3D printing for the manufacture of load-bearing structural components in wheelchairs. Abdullah et al. developed a wheelchair accessory that can push open doors and move aside obstacles utilizing small wheels, off-the-shelf components and 3D printed ABS fasteners.^8,9 They demonstrated that the 3D printed fasteners are strong enough to withstand the 50 N force encountered when pushing open a door. There has also been a few commercial ventures producing bicycle and wheelchair structural components using 3D metal printing (Rove® wheelchairs, Atherton® bicycles). In this study, we manufactured parts using several 3D printing methods and materials and quantified their strength properties to evaluate their viability for the production of customized wheelchair components.

Wheelchair users have to contend with the trade-off between stability and manoeuvrability. Configuring a wheelchair with the Center of Gravity (COG) closer to the rear wheel axle reduces propulsive effort, enhances ergonomics and improves turning control—but increases the probability of the wheelchair tipping backwards.¹⁰ To mitigate this instability, COG can be moved forward, wheelchair wheel-base can be increased and/or rear anti-tippers can be installed. Present rigid anti-tipper designs result in an uncomfortable and jerky hard stop as the wheelchair tips backwards, and they also limit the ability to raise the front casters to get over obstacles.^11,12 An anti-tipper that provides progressive resistance would allow for stable navigation while maintaining the most manoeuvrable wheelchair configuration.

In this study, we had two objectives: to design an anti-tipper that provides progressive resistance as the wheelchair tips backwards and allows sufficient range of motion (ROM) to navigate a 152 mm (6 inch) curb before engaging the hard stop, and to fabricate the design using 3D printing and test if the parts meet function and strength requirements. Inspired by articulating joints seen in ankle-foot orthoses, we designed a progressive anti-tipper that can provide up to 20° of backwards rotation before engaging a hard stop. Our design could be customized for user weight, spring stiffness preferences, range of motion, and attachment to different wheelchair models. We 3D printed our prototype using four different 3D printing methods in materials such as plastics, carbon fiber composites, hard resin and stainless steel. We performed ISO 7176-8 Wheelchair Standards prescribed strength tests for anti-tippers. We calculated the static and impact strength requirements of the anti-tipper, and performed destructive testing on an Instron Universal Testing Machine (UTM) to quantify the strength of the 3D printed samples.

2. Methods

2.1. Strength requirements

We estimated load requirements on the anti-tipper using static torque calculations, coded in MATLAB (Mathworks Inc. 2024). We have expressed values in metric units (imperial units), except when the components themselves are manufactured in standardized imperial sizes, such as wheelchair parts and fasteners. We assumed a weight of 130 kg {115 kg (∼254 lb) user and wheelchair weight of 15 kg (∼33 lb)} acting at the COG. We used the dimensions of a PDG Bentley prototype provided by Permobil with 22 inch rear wheels and 6 inch caster wheels (Figure 1 left: not to scale), although changing to 24 inch rear wheels and 8 inch casters did not affect the load calculations meaningfully. The seat of the PDG Bentley can be tilted backwards through 20° about a pivot point close to the knee, and we have performed the strength calculations for both the regular and tilted seat setting (Figure 1 Right). The anti-tipper center of rotation (Figure 1 point T) lies 165 mm (6.5 inches) below the axle center of rotation (Figure 1 point O). We set the COG (Figure 1 point M) to be 178 mm (7 inches) ahead of the center of rotation (axle) to simulate a manoeuvrable configuration. We considered up to 30° of tip to include a safety margin in our calculations, to accommodate flexion of the wheelchair frame. We computed the torque that should be produced by the anti-tippers to balance the torque produced by gravitational forces at the axle using the formulae:

{\overset{⇀}{τ}}_{T} = {\overset{⇀}{P}}_{G T} \times {\overset{⇀}{F}}_{G}

{\overset{⇀}{τ}}_{M} = {\overset{⇀}{P}}_{M O} \times {\overset{⇀}{F}}_{M}

{\overset{⇀}{τ}}_{T O} = {\overset{⇀}{P}}_{G O} \times {\overset{⇀}{F}}_{G}

{\overset{⇀}{τ}}_{O} = {\overset{⇀}{τ}}_{M} - {\overset{⇀}{τ}}_{T O}

where

{\overset{⇀}{τ}}_{T}

represents the torque produced at the anti-tipper center T, either due to the spring or due to the hard stop, which applies forces at the ground contact (Figure 1 point G).

{\overset{⇀}{τ}}_{O}

represents the net torque at the axle center O due to

{\overset{⇀}{τ}}_{M}

(gravitational torques from the mass of the wheelchair and user at M) minus

{\overset{⇀}{τ}}_{T O}

(the torque produced by the anti-tipper about the axle center O).

These calculations estimate that each anti-tipper must withstand up to 84 Nm of torque to prevent further tipping of the wheelchair when it is at an angle of 30° (Figure 1 Right).

For impact loads, we considered the 130 kg (287 lb) wheelchair falling the height of a curb of 152 mm (6 inches), which results in the anti-tipper colliding with the edge of the curb. The impact force can be estimated using the below formula:

F_{i} t_{i} = 2 m v_{i}

where F_i stands for the impact force, t_i stands for the collision time, m stands for the mass of the user and wheelchair, and v_i stands for the velocity at the time of impact. Assuming a collision time of 100 ms, we estimated the impact torques that the anti-tipper should withstand to be about 200 Nm (147.5 ft.lbs).¹³

Assuming a safety margin of three times the static load and one-and-a-half times the impact loads, we calculated our strength requirements to be:

− Static strength requirement: 252 Nm (185.9 ft.lbs) per anti-tipper

− Impact strength requirement: 300 Nm (221.3 ft.lbs) per anti-tipper.

2.2. Component design

This prototype was inspired by spring loaded hinge designs seen in ankle foot orthoses.^14–16 The prototype was designed to attach to the pre-existing anti-tipper attachment site on PDG wheelchairs, and work within the space constraints—a width of 89 mm (3.5 inches) to fit onto the existing axle plate, thickness of 38 mm (1.5 inches) to fit between the wheel and the seat frame in the tilted position, and a height of 102 mm (4 inches) to allow space between the anti-tipper and ground (Figure 2 Top). The prototype utilized 3D printed parts and off-the-shelf components for fastening and reinforcement.

The progressive anti-tipper design consists of two main components: a fixed Hub and a rotating Arm that pivots on the Hub (Figure 2 Middle). The Hub and Arm are fastened together using a shoulder bolt, which also acts as the pivot for the rotating Arm. The Hub consists of a cuboidal block that is fastened to the wheelchair axle plates, and a plate underneath with two bosses (Figure 2 Hub). The spring stop boss provides the surface to engage the die spring that produces the progressive resistance. The spring stop is reinforced using two dowel pins. The shoulder bolt boss holds a captive nut for the threaded section of the shoulder bolt.

The rotating Arm contains a channel that fits the spring stop on the Hub; the length of this channel provides the range of motion required to rotate the Arm about the Hub. Underneath the channel is the shoulder bolt hole, with a top hat bushing and thrust washer to provide smooth concentric surfaces for rotation. The Arm has a threaded hole to receive the die spring and a set screw used to preload the spring. The threaded hole can accommodate die springs of different stiffnesses; we used standard die springs with 1100 lb/inch, 600 lb/inch and 300 lb/inch stiffnesses to provide progressive resistance depending on user weight and support preferences. We used 3D printed soft elastic sleeves of Thermoplastic Polyurethane (TPU) around the die springs, as their diameters varied based on stiffness, and to prevent rubbing between the die springs and the threaded hole. Underneath this, the second hole receives the anti-tipper support rod that contacts the ground.

While the wheelchair is at rest, the Arm is held at an approximately 20° angle to the horizontal position by the extended spring (Figure 2 Rest position). As the wheelchair tips backwards, the support rod of the anti-tipper contacts the ground and rotates the Arm upwards, compressing the spring and providing progressive resistance. Once the Arm rotates through its range of motion, the top of the Arm contacts the base of the cuboidal axle attachment block of the Hub, and acts as a hard stop (Figure 2 Hard stop).

A key advantage of using 3D printing is that we can quickly manufacture customized parts to fit user preferences. For instance, during a wheelchair prescription visit, clinical staff could collect a user’s anthropometric measurements and preferences. They could then modify the anti-tipper Computer Aided Design (CAD) files before 3D printing. The anti-tipper support rod would be left floating slightly above the floor to prevent friction during level wheeling. The initial angle at which the anti-tipper support rod contacts the floor and starts providing support can be adjusted by modifying the dimensions of the spring stop and spring stop channel. The amount of progressive resistance provided can be adjusted by changing the die springs, and by preloading the spring using the set screw. Finally, the angle of tip at which the hard stop engages can also be adjusted by selecting the die spring with the right length and deflection parameters.

2.3. 3D printing

We 3D printed samples of our prototype using four different methods, and selected print settings based on literature and recommendations from experts at BCIT MAKE+.^17,18 We optimized settings considering both strength and material usage. We have detailed the print settings used in Supplementary Materials section A.

2.3.1. Fused Deposition modeling (FDM)

We 3D printed the prototype on Bambu X1 Carbon and Bambu A1 printers, using Poly Lactic Acid (eSun PLA+) and Acrylonitrile Styrene Acrylate (Bambu ASA) filaments.

2.3.2. Stereolithography (SLA)

We printed using Loctite ABS-like resin on the Phrozen Sonic Mega 8K S printer to print solid parts (100% infill) of the prototype.

2.3.3. Fused filament fabrication-composite (FFF-composite)

The Markforged Mark2 and X7 printers are capable of embedding a second continuous filament within the 3D printed part for reinforcement. We used the Onyx (Nylon with shredded carbon fiber) filament, along with continuous carbon fiber filament to reinforce the part.

2.3.4. Fused filament fabrication-metal (FFF-metal)

The Markforged MetalX printer was used to print the prototype using 17-4PH stainless steel, using a three part process (printing, solvent washing and sintering).

As our aim was to compare the strength of different 3D printing methods, we chose to fix the geometry of our design based on the product space limitations of the anti-tipper and wheelchair frame, and quantify how strength is affected by 3D printing method and print settings. For each 3D printing method, we used print settings that optimized strength while considering weight and cost. For example, 100% infill would have been the strongest setting for FDM. However, based on previous experience, a 60% infill ratio provides a reasonable trade-off between strength and weight. While we could have placed carbon fiber reinforcement in every layer of the FFF-Composite prints, we decided to use intermittent reinforcement to optimize strength while limiting cost, based on previous experience (Supplementary materials A). Alternatively, we could have modified the geometry based on the strength properties of each 3D printing method and material using FEA analysis. However, we did not find sufficient data and validated methods to apply FEA to 3D printed parts, due to their anisotropic material properties.

2.4. Function and strength tests

We tested the performance of our prototype as a progressive anti-tipper, conducted the ISO Wheelchair Standards 7176-8 prescribed strength tests, and performed destructive testing on an Instron Universal Testing Machine (UTM) (Figure 3). For the function and ISO 7176-8 tests, we used a 113.4 kg (250 lb) ISO test dummy to simulate a wheelchair user at the weight limit of the PDG Bentley-LT wheelchair design. We used a PDG Bentley prototype with 22 inch wheels and 6 inch casters provided by Permobil.

2.4.1. Function

We fitted our anti-tipper samples printed using different 3D printing methods on the PDG Bentley wheelchair loaded with the ISO test dummy. We first placed the wheelchair in a 20° tilt position; this moved the COG further backwards increasing the load on the anti-tipper (Figure 3 top left). The wheelchair was then tipped through the ROM of the anti-tipper until it came to rest at the hard stop position. We verified that a tip of 20° was sufficient to raise the front casters sufficiently to climb a 152 mm (6 inch) curb. The anti-tipper was then disassembled to check for failure or damage.

2.4.2. ISO 7176-8 strength tests

We performed the pendulum impact test and curb drop test prescribed by ISO 7176-8 for wheelchair anti-tippers. The pendulum (lateral impact) test involved striking the anti-tippers using a 1m long, 10kg pendulum raised to an angle of 31° (Figure 3 bottom left). The curb drop (upward impact) test involved driving the wheelchair down a 114.3 mm (4.5 inch) curb at 1 m/s, in such a way that the anti-tippers impact the edge of the curb (Figure 3 bottom right).

2.4.3. Instron UTM destructive testing

Using a 34TM-50 Instron UTM, we loaded the 3D printed samples until failure and quantified the ultimate strength of the different 3D printing methods (Figure 3 top right). We aimed to achieve 3X the static load estimate and 1.5X the impact load estimate (Methods 2.1). We tested 3 samples each of the PLA and ASA, four samples of Onyx, and one sample of the SLA resin and FFF-Metal prints. To ensure load on the Arm and Hub components during the UTM testing, we replaced the 3D printed set screw with a steel set screw, and the hollow anti-tipper support rod with a similar sized solid steel rod.

3. Results

The FDM prints in ASA and PLA did not have good dimensional accuracy, and required minor operations like drilling, tapping and reaming to ensure fit between the Arm and Hub and insertion of fasteners into holes. The SLA and FFF-Composite methods produced prints with good dimensional accuracy which did not require any more operations. The FFF-Metal parts had mild warping after the sintering process, attributed to the storage of the filament for a long period of time. Table 1 presents the function and strength test results.

Table 1.

Function and strength test results. The strength value is for a single anti-tipper. The weight and cost values are for two anti-tippers required on a wheelchair. For 3D printing methods that had multiple samples, we have reported average values.

Printer	Function	Pendulum impact test	Curb drop test	Strength (Nm)	Weight (gm)	Cost (USD)
Filament	Function	Pendulum impact test	Curb drop test	Strength (Nm)	Weight (gm)	Cost (USD)
FDM	✓	✓	✓	144.7	1234	38
Bambu X1C, A1
eSUN PLA+
FDM	✓	✓	✓	163.9	1194	42
Bambu X1C, A1
Bambu ASA
SLA	✓	✓	✓	126.6	1242	160
Phrozen Sonic Mega
Loctite ABS-like resin
FFF-Composite	✓	✓	✓	339.3	1004	178
Markforged X7, Mark2
Onyx+Carbon Fiber
FFF-Metal	✓	✓	✓	>725.7	3110	1180^*
Markforged Metal X
17-4PH Stainless Steel

*The cost for the metal print is an estimate including the price of printing, washing, sintering and electricity.

3.1. Function

All 3D printed samples passed the function test by providing 20° of backwards rotation; a tip of 16° is sufficient to achieve the 152 mm (6 inches) of caster clearance necessary to climb curbs. During preliminary tests with PLA samples, the spring stop on the Hub sheared off under load. Therefore, we chose to add dowel pins in the spring stop during our next design iteration.

3.2. ISO 7176-8 strength tests

All samples also passed the pendulum impact and curb drop tests without failure.

3.3. Instron UTM destructive testing

For all the 3D printed samples, failure occurred at the Hub, either by tearing at the spring stop or fracturing at the shoulder bolt hole (Figure 4). The Arm did not fail in any of our tests. The FDM samples of PLA and ASA reached a load of 144.7 Nm (107 ft.lbs) and 163.9 Nm (120.9 ft.lbs) respectively, which did not meet our safety criteria of 300 Nm (221.3 ft.lbs). The SLA resin sample reached a torque of 126.6 Nm (93.4 ft.lbs). However, the sample underwent brittle fracture (sudden shattering like glass), which does not support its use as a critical safety mechanism on wheelchairs. We had printed the Hub component of the Onyx samples in two orientations—flat on the back of the hub plate, and vertically on the smaller face of the axle attachment block. The horizontally printed samples failed at very low loads, as the applied forces caused layer separation. The vertically printed samples, with forces applied along the filament direction, exceeded our strength requirements at 339.3 Nm (250.3 ft.lbs). We stopped the test due to significant bending in the Hub component when the UTM forced displacement past the hard stop (Supplementary material B Fig 9), even though the graph appears to still be in the elastic zone (Figure 4 red). The FFF-Metal component reached a load of 725.7 Nm (535.2 ft.lbs) before we stopped the test, as the steel anti-tipper support rod was showing deformation instead of the Arm or Hub parts. We have provided more details of the analyses of the strength tests in Supplementary Materials section B.

4. Discussion

We developed a prototype for a manual wheelchair anti-tipper that imparts a spring-loaded response as the wheelchair tips backwards, providing progressive resistance before engaging a hard stop. We manufactured our design using several 3D printing methods and tested the prints for function and strength properties. Our design achieved its functional goals, stabilizing the wheelchair while providing a tip of up to 20°, which is sufficient to navigate a 152 mm (6 inch) curb. All 3D printed parts survived the ISO 7176 prescribed curb drop and pendulum impact strength tests for anti-tippers. The FDM and SLA prints had the weakest strength properties and failed during Instron tests at loads below the impact strength requirements. The FFF-Composite and FFF-Metal prints exceeded the strength requirements. These results support the viability of 3D printed load bearing wheelchair components.

Progressive anti-tippers have the potential to improve wheelchair functionality. The progressive anti-tipper allowed us to place the axle 178 mm (7 inches) behind the COG on our wheelchair. In this position, the wheelchair is unstable but highly manoeuvrable. While the wheelchair can tip backwards if the user accelerates quickly, they do not experience a jerky collision with the hard stop in rigid anti-tippers, and can continue to propel the wheelchair and regain stability. Based on preliminary feedback from users, the progressive resistance also reduces the sensation of falling and the anxiety response associated with tipping backwards in a wheelchair. Kirby and colleagues developed and tested the Arc Rear Anti-tip Device (arc-RAD), an anti-tipper that rotates to allow increased rear tip before engaging the hard stop.^11,12,19,20 However, we do not think this design provides a spring-like progressive response to rearward tip. Kirby et al. showed that the arc-RAD increases tipping ROM which has several advantages, such as improved performance of wheelchair users on wheelie dependent wheelchair skills, and reduced seating pressure.^12,20 Presently, there are few commercial examples of progressive anti-tippers, such as the Ki Mobility’s Dynamic 5th Wheel and the PDG mobility Bentley LT-R. Our prototype is easily customizable—the Hub can be modified to attach to different wheelchair designs, the channel length can be increased to change ROM, and spring stiffnesses can be changed to accommodate response levels. The progressive anti-tipper has some disadvantages. For example, as the wheelchair rotates backwards much further than with rigid anti-tippers, and the ground contact point of the anti-tipper support rod is pulled forward while tipping, the COG might move behind the anti-tipper ground contact point, causing a fall. Thus, the anti-tipper rod had to be longer than in a rigid anti-tipper, contacting the ground an inch further behind the wheel. This increases the footprint of the wheelchair and might reduce navigability in tight spaces.

3D printing technology encompasses several different methods and materials with different levels of barriers to entry. FDM printing has the least barrier to entry; printers and materials are relatively inexpensive (e.g. a Bambu A1 costs 400 USD, while a larger Bambu X1C costs 800 USD), and does not require specialized training/engineering skills. While most materials are non-toxic, printing and post-processing certain materials like ASA can produce toxic fumes which require specialized material handling. We could develop a set of protocols that allow clinical staff to customize the design for each individual user, test user preferences, then print and assemble the parts within one or two days. Our results show that FDM prints reinforced with off the shelf fasteners can produce very strong parts. While our present FDM print did not meet the 300 Nm strength requirement, we are exploring design improvements including a thicker Hub plate with inset bolts to compress print layers, that can sufficiently strengthen the prints. SLA printing is also relatively easy to operate, but does require handling toxic materials. While we tested only one SLA resin which suffered brittle fracture, we aim to explore more resins that are developed for industrial and high impact applications. The FFF-Composite method—while much more expensive (Markforged Mark2–15000 USD and X7–80000 USD)—produced parts with high dimensional accuracy, low weight, and met the strength requirement of the progressive anti-tipper, making it the most suitable method among the ones we tried. The level of expertise and material handling requirements are the same as for FDM printing. The FFF-Metal method—while requiring expensive equipment (Markforged MetalX–150000 USD), long manufacture times of up to 2 weeks, toxic material handling, and specialized training to operate—produced the strongest parts among the methods we tried. The metal print is about six times the cost and three times the weight of the Onyx composite print; we are exploring design improvements to reduce material usage/weight of the metal print. Given that present rigid anti-tippers on wheelchairs retail for 100–200 USD, the manufacturing costs of our progressive anti-tipper design are reasonable (Table 1). All the prices cited here are approximate, as prices are reducing rapidly for 3D printing. We have also not explored other 3D printing technologies that produce strong parts, such as Multi-Jet Fusion (MJF) and Direct Metal Laser Sintering (DMLS). The DMLS method has been used commercially to produce metal lug-and-tube design wheeled devices, such as Rove® Wheelchairs, and Atherton® bikes. Our results show that 3D printing has potential use for the manufacture of customized wheelchair components, and further fatigue strength and real-world usability tests are warranted.

4.1 Future work

Future work will include optimizing material requirements based on strength properties for the different 3D printing methods. We were constrained by the limitations of FEA and shape optimization methods in optimizing 3D printed designs, due to their anisotropic material properties and internal infill geometry. We are developing a test rig to evaluate the fatigue properties of our designs. Once the designs are finalized, we intend to collect usability data from end users using mixed-method analyses. These strength, fatigue and usability tests will inform further research into other load bearing wheelchair components that require customization.

Supplemental material

Supplemental material - Viability of 3D printing for load-bearing wheelchair components: A progressive anti-tipper prototype

Supplemental material for Viability of 3D printing for load-bearing wheelchair components: A progressive anti-tipper prototype by Sayed Naseel Mohamed Thangal, James Formby, Torr Brown, Jaimie Borisoff in Journal of Rehabilitation and Assistive Technologies Engineering

Footnotes

Acknowledgements

We would like to thank BCIT MAKE+ and AAMTECH staff for providing design and manufacturing support for this project. We thank Rohan Korsch-Sharma for support with SLA printing and recommendations for FDM print settings, Shadi Sabeti for support with FFF-Composite reinforcement, and Fardin Barekat for support with FFF-Metal printing.

ORCID iDs

Sayed Naseel Mohamed Thangal

Jaimie Borisoff

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This project was supported by Mitacs fellowship IT 35230 to SNMT in partnership with PDG Mobility, and CFI and Natural Sciences and Engineering Research Council of Canada Grant NSERC RGPIN-2019-05458 funding to JB.

Declaration of conflicting interests

The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: This project is partly funded through a Mitacs fellowship to SNMT from PDG Mobility, and TB and JF are employees of Permobil.

Supplemental material

Supplemental material for this article is available online.

References

Arledge

Armstrong

Babinec

, et al. RESNA Wheelchair Service Provision Guide. Resna (Nj1) 2011.

Pousett

Lizcano

Raschke

. An investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. Canadian Prosthetics & Orthotics Journal 2019; 2(1): 31008. https://doi.org/10.33137/cpoj.v2i1.31008

Paterson

Donnison

Bibb

, et al. Computer-aided design to support fabrication of wrist splints using 3D printing: A feasibility study. Hand Ther 2014; 19(4): 102–113. https://doi.org/10.1177/1758998314544802

Lee

. Design and development of a customized 3D-printed assistive device using modular 3D blocks. Disabil Rehabil Assist Technol 2025; 20: 1–13. https://doi.org/10.1080/17483107.2025.2462170

Vennam

Vijayasankar

Pati

. 3D printed personalized assistive devices: a material, technique, and medical condition perspective. Appl Mater Today 2024; 40: 102403. https://doi.org/10.1016/j.apmt.2024.102403

Ribeiro

Cimino

Mayo

, et al. 3D printing and amputation: a scoping review. Disabil Rehabil Assist Technol 2021; 16(2): 221–240. https://doi.org/10.1080/17483107.2019.1646825

Waldburger

Schaller

Furthmüller

, et al. 3D-printed hand splints versus thermoplastic splints: a randomized controlled pilot feasibility trial. Int J Bioprint 2021; 8(1): 474. https://doi.org/10.18063/ijb.v8i1.474

Jalal

Shaikh Mohammed

. Low-cost low-tech obstacle pushing/gliding wheelchair accessory. Disabil Rehabil Assist Technol 2019; 14(8): 849–858. https://doi.org/10.1080/17483107.2018.1539130

Abdullah

Shaikh

. Modeling and simulation of two wheelchair accessories for pushing doors. Assistive Technology 2018; 30(4): 165–175. https://doi.org/10.1080/10400435.2017.1293193

10.

Tomlinson

. Managing maneuverability and rear stability of adjustable manual wheelchairs: an update. Phys Ther 2000; 80(9): 904–911.

11.

Kirby

. Anti-tip devices for wheeled conveyances including wheelchairs and method related thereto. US Patents March 2003; 6,530,598.

12.

Kirby

Corkum

Smith

, et al. Comparing performance of manual wheelchair skills using new and conventional rear anti-tip devices: Randomized controlled trial. Arch Phys Med Rehabil 2008; 89(3): 480–485. https://doi.org/10.1016/j.apmr.2007.08.163

13.

Kerdanyan

Minkel

Maneekob Kunwong

, et al. Measurement of force and acceleration experienced in a manual wheelchair. In: Proceedings of the 28th Annual RESNA Conference, Atlanta, Georgia, June 2005, pp. 25–27.

14.

Bowman

. Single-Case Study: Traditional Thermoplastic AFO Versus Adjustable Dynamic Response -A Crossover Single-Case Study. JPO: Journal of Prosthetics and Orthotics 2010; 22(2): 84–90. https://doi.org/10.1097/jpo.0b013e3181ccbed5

15.

Amerinatanzi

Zamanian

Shayesteh Moghaddam

, et al. Application of the superelastic NiTi spring in ankle foot orthosis (AFO) to create normal ankle joint behavior. Bioengineering 2017; 4(4): 95. https://doi.org/10.3390/bioengineering4040095

16.

Kobayashi

Orendurff

Hunt

, et al. The effects of an articulated ankle-foot orthosis with resistance-adjustable joints on lower limb joint kinematics and kinetics during gait in individuals post-stroke. Clinical Biomechanics 2018; 59: 47–55. https://doi.org/10.1016/j.clinbiomech.2018.08.003

17.

Kuznetsov

Solonin

Urzhumtsev

, et al. Strength of PLA components fabricated with fused deposition technology using a desktop 3D printer as a function of geometrical parameters of the process. Polymers (Basel) 2018; 10(3): 313. https://doi.org/10.3390/polym10030313

18.

Syrlybayev

Zharylkassyn

Seisekulova

, et al. Optimisation of strength properties of FDM printed parts—A critical review. Polymers (Basel) 2021; 13(10): 1587. https://doi.org/10.3390/polym13101587

19.

Kirby

MacDonald

Smith

, et al. Comparison between a tilt-in-space wheelchair and a manual wheelchair equipped with a new rear anti-tip device from the perspective of the caregiver. Arch Phys Med Rehabil 2008; 89(9): 1811–1815. https://doi.org/10.1016/j.apmr.2008.01.019

20.

MacDonald

Kirby

Smith

, et al. Sitting Pressure in the Tilted Position: Manual Tilt-in-Space Wheelchair: vs: Manual Wheelchair with a New Rear Antitip Device. Am J Phys Med Rehabil 2009; 88(1): 61–65. https://doi.org/10.1097/PHM.0b013e31818dff2a

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