Limbs & Things is a leader in medical training and simulation of human anatomy models. The company invited IDC in the UK to help its products improve performance through design and development, simplify assembly, and smoothly push the products into production through proper production-oriented design.
Based on the requirements of the project, the IDC team needs to develop a very anatomically sophisticated model, including the upper arm and the lower arm, and an internal structure that can reflect the fracture, and by adjusting the tension, the contraction force is changed. The fracture state of the model should be as true and consistent, and the anatomical details of muscles, skin and bones should be extremely realistic.
Manufacturing-oriented design also needs to be taken into consideration. Reducing the number of components and simplifying assembly are one of the design goals.
Since the skin of the model will be constantly touched and used during the training process, the simulated hands and skin are also designed to be replaceable.
Fracture of the lower end of the radius occurs on the radius, near the wrist. The technique of reduction of fracture at the lower end of the radius is a non-invasive method of treatment. To do this, the clinician must stretch the fracture part and manipulate the injured hand to reset to the correct position.
The Limbs & Things model aims to provide doctors with a training experience that can practice this complex reduction technique repeatedly and refix the arm with plaster. This design can be used to reflect common errors, such as when the arm is not accurately fixed when the plaster is fixed, it will immediately bounce back to its original state.
The first challenge for IDC engineers is to develop a design that mechanically simulates human wrist movements. The design has been simplified from the technical form of many strap components to a simple two-way hinge with only a few functions to simplify assembly.
Silicone is the best material for making realistic skin. However, the low friction performance of silicone can cause problems with the skin rotating around the internal structure of the arm and the bone structure of the hand. The IDC team worked with the material manufacturers we have worked with to find a suitable adhesive material that can perfectly bond the two parts of the hand together. At the same time, some mechanical functions are included to avoid skin falling off during arm assembly.
The designer has developed an integrated silicone skin that users can easily peel off and replace when needed.
A key feature of this product is the ability to adjust the tension generated during fracture contraction. Because it can replicate the difference of muscle tension in different groups, this will gradually increase the difficulty of training. The tension can be changed by adjusting the hidden screw located at the elbow.
The IDC team also developed a clamping device on the upper arm, where the model can be fixed to the bracket if necessary. The design of the skin makes the internal structure and fixed features well hidden.
Manufacturing-oriented design is an important element of this project. Limbs & Things hopes that the design can be printed in 3D in the early stage. Once the sales reach the appropriate level, it will be manufactured through large-scale injection molding. Most of the production work will be completed within Limbs & Things.
IDC was able to simplify assembly while improving performance, and finally successfully delivered a design that could be mass-produced. The reduction training products for fractures of the lower end of the radius have now been officially put into production and have received good feedback from clinicians.

Product design and development cases: idcdesigncn.com/medical/limbs-things-anatomical-model/
UK IDC official website: idcedsigncn.com
case of medical product design: idcdesigncn.com/medical/cases