Production documentation

Ergonomic Crutches Design for Enhanced Mobility and Comfort

Table of Contents

Project description

This project development of an innovative, user-friendly crutch designed to improve the mobility and experience of those with temporary or fixed mobility restrictions. A key innovation of the crutch is a push-button locking system that makes it easy for users to change the height to make it fit their needs. This mechanism provides locked functions for safety and reliability against unintended slippage to provide better safety and stability while in use.

Project context

Clinical needs

The clinical need for this ergonomic crutches design, specifically the length-adjusting crutch shaft, mainly revolves around:
•         Improving mobility
•         Comfort
•         Safety for individuals who rely on crutches,
This is applicable for users with temporary or permanent mobility impairments.
This innovation addresses:
1.        Improved stair navigation,
2.        Reduced physical strain,
3.        Enhanced balance and stability
4.        Adaptation for varying mobility levels,
5.        Increased independence
6.        Prevention of overuse injuries.
The ergonomic adjustments design addresses the significant clinical gap in crutch mobility, particularly for those dealing with the everyday challenge of navigating stairs with fixed-length crutches.

Existing solutions

•         The existing solutions concerning mobility aids include crutches, which are typically made of metal or wood and are, therefore, not equipped with required essentials such as height adjustment and comfortable gripping.
•         Another one is forearm crutches, which are more suitable for patients who plan to use those walking sticks on a constant basis. However, these crutches rely on convenience factors that are rather large and uncomfortable after hours of use.
•         Foldable crutches are convenient for portability purposes
•         Smart crutches have come as a much more sophisticated product, and few of them are designed with the sensors that are used to study gait.

Proposed solution and its innovative aspects

The concept for this project is to create a new kind of crutch designed to enhance the mobility of such patients both for temporary and long-term disabilities. The design maintains abilities congruent with ergonomics to improve convenience and usability but dealing specifically with the disadvantages the standard crutches, for example, pain, problems with stairs, and instability.
This feature of crutch entails the use of a push button lock whereby the user can easily change the height of the crutch once locked. It also makes it possible to setup to fit different users, height and size of the users; this enables better posture and reduce on the strain on the body while using the crutch. The push-button system is created to fasten the crutch at the preferred height firmly with no slippage, to add more safety to the user.

Additional features of the design include:
Dynamic adjustability: This aspect is well address by the fact that crutch height can be adjusted regardless of the surface; may it be stairs or otherwise.
Stability and grip: A high friction non slip rubber cap provides for safe and sure ground contact, the push button locks the crutch into position and ensures no movement along the crutch shaft during usage.
Ergonomic support: The handle of the crutch and the underarm support Curve to adjust the pressure quandary of the user’s body weight and this reduces stress more so, when the user spends many hours utilizing the crutch handle.

Intended users

This product shall benefit anyone who struggles with mobility. These include
•         Short-term users: persons with short-term physical impairments like fractures, sprains, infections, or operations that, for one reason or another, make them find it difficult to move from one place to another.
•         Long-term users: Patients with physical disorders requiring wheelchairs and other mobility aids on a regular basis, for example, cerebral palsy, multiple sclerosis, or amputation.
•         Rehabilitation patients: Patients who have suffered through an accident, disease, or disability and need to use crutches during a physical therapy session.
•         Elderly individuals: Neuromusculoskeletal diseases that affect elderly people and make them have restricted mobility and might need assistance while walking to avoid stumbling.
These users may require solutions that are comfortable when in use, that are adjustable, and that possess highly technical features based on the time and severity of the mobility requirements.

ISO compliance

EN ISO 13485:2016
This standard specifies requirements for all entities involved in medical devices, in all stages of the product life cycle: from design to manufacture to installation to disposal. Ubora Platform is structured to be a guideline for design activities in compliance to this standard.
EN ISO 14971:2012
This standard specifies requirements for designers and manufacturers of medical devices, in order to minimize the risk of the device itself. There is no “risk zero” device but many activities can be implemented to reduce and manage risk. This standard provides useful checklists and also guidance on the most widespread risk management techniques such as FMEA.
MEDDEV 2.7.1 rev 4 CLINICAL EVALUATION: A GUIDE FOR MANUFACTURERS AND NOTIFIED BODIES UNDER DIRECTIVES 93/42/EEC and 90/385/EEC
This guideline provides information on methods used to assess the clinical performance and the clinical benefit of a medical device.
IEC 62366-1
This standard provides guidance on how to manage the human factors while designing a medical device (usability engineering).
EN ISO 15223-1:2016
This standard lists a series of symbols that may be applicable in labels of medical devices.
ISO 10993-1

Design and prototyping

User and evironment

Who is the intended user?
Self-user/patient
Is training required in addition to the expected skill level of the intended user?
No
Is any maintenance or calibration required by the user at the time of use?
No
Where will the technology be used?
rural settings, urban settings, outdoors, indoors, at home, primary level (health post, health center), secondary level (general hospital), tertiary level (specialist hospital)

Health technology specifications

Dimensions (mm³)
1100 mm x 100 mm x 50 mm
Weight (kg)
1 kg
Does it require the use of consumables? For example, disposable batteries, disposable electrodes, etc.
No
Estimated life time
5 Years
Estimated shelf life
3 Years
Can it have a telemedicine or eHealth application?
No
Does it use any kind of software?
No
Is it portable?
Portable
Type of use
Reusable
Does the technology require maintenance?
No
Energy requirements
Mechanical energy (e.g. manually powered)
Facility requirements

Design prototyping

Quality criteria and validation test

This is the link to our Finite Element Analysis
https://drive.google.com/file/d/1m7_4UBbJvPRiON3lTiz4o8CHdRIfKAzV/view?usp=sharing
Model Setup in FEA
Geometry and Meshing:

In the crutch assembly model, one can find the bottom ABS support, top ABS handle, aluminum connector, and the ABS shaft connector in complex geometries.
The model is discretized into a mesh of finite elements (solid mesh) where localized material behavior is captured by each element.
A high-quality mesh is used throughout, such as a Curvature-Based Blended Tri with the maximum element size of 26.7785 mm and a minimum of 1.33879 mm in order to precisely capture the place of stress concentration.
Material Properties:

The different material properties used in the crutch are ABS plastic and 1060 Aluminium alloy, whose density, Young's modulus, Poisson's ratio, and yield strength are defined in the simulation.
Each material has been assigned the behaviour of being linear elastic, allowing an accurate assessment of the amount of deformation seen under applied load with reasonable computational effort.
Boundary conditions and constraints:

The crutch is fixed at the base—a bottom ABS support—that simulates ground contact, where movement is constrained and the load is mainly directed downward.
A downward force is applied at the top handle, representative of the user's weight. As such, a real-world loading condition could be simulated in which a user presses down on the crutch.
Load Conditions:

A vertical load equivalent to the weight of a person acts on the handle for a simulation representing a static load case.
Other test scenarios include changes in force direction and cyclic loading to check for fatigue resistance in a wide variety of conditions.
3. Crutch Analysis: Key FEA Results
Stress Distribution-von Mises Stress:

The distribution of the von Mises stresses in the crutch assembly can indicate regions with higher levels of stress that may easily compromise the material to yield or fail. The maximum von Mises stresses from FEA were 1.361e+06 N/m2, and these are compared with the yield strength of the materials so that the design remains at a safe limit of stress.

Displacement and Deformation:

Displacement results show the amount the crutch deforms under the load applied. The maximum displacement observed was 0.01159 mm. The least value of displacement is desirable since it reflects in structural rigidity, hence reducing the chances of fatigue over time. This pattern of displacement identifies if the handle, shaft, or connectors are overbent or shifted in any way that would affect user comfort or safety. Strain Analysis: Equivalent strain results are showing the highly deformed areas that come within the elastic range, and the maximum equivalent strain is 1.309e-05. These results help check for any material deformation or plasticity under normal conditions of load, with the added value that the crutch will be able to sustain cycles of repeated loading without setting.

Tools Required:

Screwdriver (Phillips).

Torque wrench.

5. Complete Guidelines for Prototyping

Tools and Equipment:

Cutting and Boring Machine for aluminum shaft manufacturing.

3D printer for ABS found in handle and other locking parts.

Non-slip rubber tips injection molding equipment.

Material Procurement:

Finished product is ABS plastic procured from [Supplier Name].

Supplied aluminum alloy rods from [Supplier Name].

Rubber compound of high friction coefficient supplied by [Supplier Name].

Production Process:

Trim the aluminium shaft to predetermined size.

15 As for the machine, it grooves for the adjustable mechanism.

Make ergonomic handle by 3D printing and then screw it into the shaft.

Prepare rubber tips and then put them on the shaft.

Check and verify each crutch against loads needed on the frameworks.

Quality Assurance

Testing Procedures:

In the mode of operation a static load test was performed with a vertically applied force of up to 800N.

Fatigue testing: Run the test to perform, so that it replicates the usage for 100000 times.

Measurement of the coefficient of friction of rubber tip on different surfaces.

Validation Standards:

ISO 10993: Membership in the bio-friendly materials category.

ISO 13485: This research theme deals with quality management for medical devices.

Packaging and Labeling

Packaging Instructions:

Crutches have to be stored in a foam lined box to avoid any damage as they can really ill afford it.

Provide a user manual and a warranty formalities document.

Labeling Requirements:

Specify characteristics in ISO 15223-1 appropriate symbols (e.g., reusable, weight capacity).

They must contain cautionary and usage information to avoid improper or incorrect usage leading to either injury or malfunction.

Maintenance and User Manual

Usage Instructions:

Bend or extend the crutch in the required length using the push button located near the bottom end of the crutch.

Check that it locks and make sure that the mechanism makes a clicking sound after engaging the lock.

Maintenance:

Do not wash them with water, though you should clean them with a damp cloth and mild soap.

To have a look at the rubber tips of the rollers and replace them when damaged.

Check the actual working of the locking mechanism from time to time.

Safety Precautions:

Avoid its uses in loads that have a weight higher than 120 kilogrammes.

It shall also only be applied on stable non-washable non-staining surfaces.

Ergonomic Crutches Design for Enhanced Mobility and Comfort