Key words terms (KWT)

1. Open-source hardware
2. Distributed manufacturing
3. Assistive technology
4. Orthopaedic crutch
5. Forearm crutch
6. 3D printing
7. Medical devices
8. Sustainable medical technology
9. Mechanical testing
10. Replicability
11. Accessibility
12. Joint design
13. Adhesive joints
14. Bolted joints
15. Stress concentration
16. ISO 11334

Strategies

Literature was identified primarily through Google Scholar using combinations of the key terms listed above. Additional sources were obtained by following citations within highly relevant publications, searching standards databases (ISO), consulting reports from international organizations (WHO), and reviewing open-source hardware repositories (Open Science Framework and Open Hardware Journal). Preference was given to recent peer-reviewed publications, internationally recognized standards, and foundational papers in distributed manufacturing and open-source hardware.

This project investigates methods for improving the accessibility, manufacturability, and replicability of open-source forearm crutches through redesign of the structural joint architecture.

Traditional assistive devices frequently rely on commercially manufactured hardware and centralized supply chains, limiting accessibility in many low-resource settings. Open-source distributed manufacturing has emerged as an alternative approach that allows assistive devices to be fabricated locally using widely available 3D printers and materials.

This work specifically examines whether replacing conventional screw-fastened joints with hardware-minimized fastening systems—including adhesive interference-fit joints and threaded collet compression joints—can maintain or improve mechanical performance while simplifying assembly and reducing dependence on externally sourced components.

The work evaluates both engineering performance and broader design considerations such as accessibility, repairability, manufacturability, modularity, and sustainability.

More than 2.5 billion people worldwide require at least one assistive technology, with this number expected to exceed 3.5 billion by 2050 due to aging populations and increasing prevalence of chronic disease.

Despite growing need, access to assistive technology remains highly unequal. Many individuals lack access because of:

• Cost
• Geographic isolation
• Limited healthcare infrastructure
• Dependence on centralized manufacturing
• Supply chain disruptions
• Limited availability of replacement parts

Open-source distributed manufacturing offers an opportunity to fabricate assistive devices locally using affordable desktop 3D printers.

However, successful fabrication alone does not guarantee successful implementation. Devices should also be:

• Easy to assemble
• Easy to repair
• Highly replicable
• Independent of specialized hardware
• Mechanically reliable

This research addresses these practical implementation barriers.

Development of open-source assistive technologies has progressed considerably over the past decade. Recent open-source forearm crutch designs have demonstrated mechanical performance approaching commercial products while substantially reducing manufacturing costs.

Current limitations include:

• Reliance on screws and standardized hardware
• Complex assembly procedures
• Localized stress concentrations around fasteners
• Reduced accessibility in regions where hardware availability is limited

Little research has evaluated alternative fastening strategies that simultaneously improve structural performance and simplify distributed manufacturing.

• Individuals requiring mobility aids
• People with disabilities
• Elderly populations
• Rehabilitation clinics
• Hospitals
• Prosthetics and orthotics clinics
• Humanitarian organizations
• NGOs
• Community fabrication laboratories (FabLabs)
• Makerspaces
• Healthcare providers
• Engineers
• Designers
• Open-source hardware developers
• Researchers
• Manufacturers
• Policy makers
• International health organizations (WHO)

This research is particularly applicable to:

• Low-resource healthcare systems
• Rural and remote communities
• Humanitarian aid settings
• Disaster relief
• Developing countries
• Community makerspaces
• Distributed manufacturing networks
• Educational institutions
• Open-source hardware communities

Source: https://iris.who.int/server/api/core/bitstreams/17a1cbf6-be26-466c-9fca-ab80eeb2d192/content

• Establishes the worldwide need for assistive technologies.
• Reports that over 2.5 billion people currently require at least one assistive product, with demand expected to exceed 3.5 billion by 2050.
• Highlights large disparities in access between countries (approximately 3–90% coverage).
• Identifies barriers including affordability, infrastructure, trained personnel, and supply chains.
• Provides justification for developing lower-cost, locally manufacturable assistive devices.
• Serves as the primary motivation for improving accessibility through distributed manufacturing.

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Source: https://www.researchgate.net/publication/389172785_Open-source_3D_printable_forearm_crutch/link/67b7821596e7fb48b9c8f2a0/download

• Introduces the original open-source forearm crutch design.
• Demonstrates that a 3D printed forearm crutch can satisfy structural requirements while remaining affordable.
• Uses modular screw-fastened joints.
• Establishes the baseline design modified in the current study.
• Discusses distributed manufacturing as an approach for increasing accessibility.
• Identifies opportunities for future design improvements.

Source: https://www.medrxiv.org/content/10.64898/2026.02.13.26345756v2

• Provides the newest iteration of the open-source forearm crutch.
• Demonstrates mechanical validation of the design.
• Compares performance with commercial devices.
• Reinforces the feasibility of distributed manufacturing.
• Continues to rely on hardware-fastened joints.
• Leaves opportunities to investigate alternative fastening systems.

Source: https://www.medrxiv.org/content/10.64898/2026.02.13.26345756v2.supplementary-material

• Contains detailed testing procedures.
• Includes additional mechanical data.
• Provides supplementary figures and analyses.
• Useful for reproducing experimental methods.
• Assists interpretation of reported mechanical performance.

Source: https://osf.io/n8m5y/files/osfstorage

• Contains complete CAD files.
• Includes printable STL and STEP models.
• Provides documentation for distributed manufacturing.
• Demonstrates open-source design transparency.
• Serves as the starting point for redesigning the crutch joints in this study.

Source: https://link.springer.com/article/10.1007/s10668-012-9337-9

• Introduces distributed manufacturing concepts.
• Explains environmental and economic benefits of localized production.
• Discusses sustainability advantages.
• Supports reducing dependence on centralized manufacturing.
• Demonstrates how distributed manufacturing enables community-based production.

Source: https://ojs.lib.uwo.ca/index.php/openhardware/article/view/17830

• Explains the origins and philosophy of open-source hardware.
• Reviews development of the open hardware movement.
• Discusses transparency and collaborative design.
• Explains why open hardware promotes innovation and accessibility.
• Provides background for distributed manufacturing.

Source: https://www.law.nyu.edu/sites/default/files/DistributedManufacturingofOpenHardware.p

• Reviews distributed manufacturing of open hardware.
• Discusses intellectual property considerations.
• Explains logistical benefits of local manufacturing.
• Highlights challenges including quality assurance and regulatory compliance.
• Discusses implementation in healthcare technologies.

Source: https://www.cambridge.org/core/journals/proceedings-of-the-design-society/article/identifying-the-factors-affecting-the-replicability-of-open-source-hardware-designs/02509F521214AFF0124B005C348875C7

• Defines replicability in open-source hardware.
• Identifies factors that influence successful reproduction.
• Highlights documentation quality as a major contributor.
• Discusses manufacturing complexity.
• Supports minimizing specialized hardware.
• Suggests design simplification improves accessibility.

Source: https://www.cambridge.org/core/journals/design-science/article/designing-for-replicability-a-qualitative-empirical-study-on-the-replication-of-opensource-machine-tools/B75B173A1D57431A53974CB79A4DE3F5

• Investigates replicability in distributed manufacturing.
• Focuses on low-resource implementation.
• Demonstrates importance of reducing assembly complexity.
• Identifies documentation and modularity as key factors.
• Supports hardware-minimized design philosophy.

Source: https://www.sciencedirect.com/science/article/pii/S0957415813001153

• Reviews additive manufacturing workflows.
• Discusses optimization of printing parameters.
• Summarizes advantages of fused filament fabrication.
• Provides methodology applicable to medical devices.
• Supports manufacturing decisions used in this project.

Source: https://soar.wichita.edu/server/api/core/bitstreams/63f29faa-f537-4cf3-86a8-3258861fbe95/content

• Investigates stress concentrations surrounding bolted holes.
• Demonstrates how holes create localized stress amplification.
• Explains crack initiation mechanisms.
• Supports elimination of screw holes in redesigned joints.
• Provides theoretical basis for structural reinforcement.

Source: https://www.researchgate.net/publication/287239966_Peterson's_Stress_Concentration_Factors_Third_Edition

• Standard reference for stress concentration theory.
• Quantifies stress increases around geometric discontinuities.
• Supports theoretical discussion of screw-hole removal.
• Useful reference for interpreting failure locations.
• Provides equations and correction factors for stress analysis.

Source: https://eprintspublications.npl.co.uk/2130/1/MATC65.pdf

• Compares adhesive and mechanical fastening methods.
• Reviews advantages and disadvantages of each approach.
• Discusses load transfer characteristics.
• Compares common failure mechanisms.
• Supports evaluation of the adhesive interference-fit joint.

Source: https://www.iso.org/standard/36054.html

• Specifies testing requirements for elbow crutches.
• Defines static loading procedures.
• Establishes performance criteria for structural evaluation.
• Enables standardized comparison between crutch designs.
• Forms the basis of the experimental methodology.

• Adhesive bonding between PETG and wood
• Mechanical properties of PETG
• Threaded collet fastening systems
• Compression-based load transfer mechanisms
• Fatigue testing of mobility aids
• Repairability metrics for open-source hardware
• Life-cycle assessment of distributed manufacturing
• Economic comparison of locally manufactured versus commercial assistive devices
• Human factors and usability of forearm crutches