Methods and Apparatus for Testing Material Properties of an Orthosis

Abstract/Technology Overview

An orthosis is a customized medical device to aid in the support, correction and/or alignment of the human body. It is used to counteract the effect of an actual or developing deformity, such as the use of a spinal orthosis (brace) for patients with spinal scoliosis. It may also aid in improving movement impairments. For example, an Ankle Foot Orthosis (AFO) can counteract the effects of a foot drop in stroke patients.

The conventional process of fabricating an orthosis involves a complex process of casting, rectification, fabrication and finishing. It is labour intensive, requires large amount of space for equipment and machinery, time consuming and is also dependent on the workmanship and skills of the Orthotist and Technicians. The conventional process also does not allow any further room for customization or design optimization.

Additive manufacturing allows the fabrication process for an orthosis to be shortened. The process involves less material wastage and allows for design of the orthosis to be optimized for function and adjusted to incorporate additional components for comfort. However, there are currently no methods of bench-testing for orthosis manufactured by additive manufacturing. There are also no manufacturing protocols and industrial standards.

This invention relates to a method and apparatus for bench-testing an orthosis. It can be used to test both additive manufactured orthoses and conventional orthoses. In particular, it provides a systematic method and parameters for analyzing the properties of the materials used in additive manufactured orthoses in terms of material stiffness and fatigue resistance.

Technology Features, Specifications and Advantages

The critical properties to ensure the functional performance of an orthosis, is its material stiffness and fatigue resistance. The invention provides a method of testing material which mimics the forces applied when the orthosis is worn by a patient. The method of the invention is applicable to orthoses including upper limb orthoses, lower limb orthoses and spinal orthoses. Upper limb orthoses include clavicular and shoulder orthoses, arm orthoses, elbow orthoses, forearm-wrist orthoses, forearm-wrist-thumb orthoses, forearm-wrist-hand orthoses and hand orthoses. Lower limb orthoses include foot orthoses, ankle-foot orthoses, knee-ankle-foot orthoses and knee orthoses.

An AFO is secured in the testing rig and the testing rig can be divided into three main areas of interest. The top section, where force is applied from the actuator to the upper rod, mid-section, where force is transferred from the rod to the AFO, and bottom section, where the AFO is grounded. The top section includes an actuator which may be any type of linear actuator provided it can apply sufficient force. The actuator drives the actuator rod to move in a downward motion to a certain extent on each movement. The actuator rod is connected to a load which measures the force applied by the actuator at the point where the downward movement stops. The applied force may be conveyed to a computer in operative association with the load cell. The corresponding force applied to the orthosis can be calculated using static equations of motion. 


Potential Applications

Existing additive manufacturing service providers do not conduct bench-testing of their 3D-printed devices that are meant to be worn by patients (in the Healthcare Industry). The quality of these orthoses (Medical Class A devices) could be compromised resulting in safety issues and litigations. We anticipate that testing for these orthoses will eventually become a standard requirement by various regulatory bodies.

Types of orthoses that can be 3D-printed includes AFO, Hip-Knee-Ankle Foot Orthosis (KAFO), Supra-malleolar Orthosis (SMO), Hinged AFOs, Cranial Helmets and Spinal Orthotics (Braces). Parts of a prosthetic device can also be 3D-printed. These include below & above knee prosthetic sockets, upper limb prosthetic sockets and the prosthetic shell or cover (body).

The systematic set of methods to bench-test additive manufactured orthoses can be used by service providers to ensure the material properties and design of orthoses meets the parameters and standards of conventionally made orthoses. Future possibility of a certification mark or trademark can be applied.

Customer Benefit

With new standards of testing orthoses, the customer (patients) will be able to receive a product which is not compromised in terms of integrity and functionality. Patients will also be able to have their orthoses undergo further customization in terms of design and function with the availability of a bench-testing method to verify its parameters. Optimizing design and function will lead to greater comfort for the users whilst still maintaining or in some cases improving effectiveness.

Customers (service providers, manufacturers) will be able to meet the required manufacturing standards for their 3D-printed orthoses. This also provides their consumer the confidence for the safety and reliability of their manufactured products.

Customers (educational institutions, researchers) would be able to test their new study prototypes of varying orthotic material design or new materials and compare them to conventionally-made orthoses.

Technology Owner

Evangeline Ng


National Health Innovation Centre Singapore

Technology Category
  • Medical Devices
  • Additive Manufacturing
Technology Status
  • Available for Licensing
Technology Readiness Level
  • TRL 9