Today's prosthetic systems are constructed with fixed components that often results in users becoming provided with variants of systems, where the different systems are specially adapted for specific activities and purposes. Which then leads to that different sports and Activities require different components, this often leads to that orthopedic engineers produces several prosthetic systems for patients who all require their own separate sockets. The socket is the component which is directly adapted for the specific the individual, which is based on a mold the orthopedic engineers take of the patient's residual limb to achieve a good fit.

The systems are designed with locked components, which means that patients will be bound to change the entire leg to change between different systems for specific activities. The socket is designed to create a pressure around the residual limb as soft parts are compressed, and this means that each change provides an increased risk of swelling.

If a patients residual limb start to swell it increases the surrounding pressure that occurs between the residual limb and the socket which can result in pain and discomfort and that the socket can not be connected to the residual limb.

It is not uncommon for a patient to be provided with between two to six different prostheses adapted for different purposes resulting in a large amount of sockets prepared for each patient. Which in health care systems results in an increased patient time because orthopedic engineers repeat the manufacture of sockets for every system. Prostheses are designed to replace lost extremities which results in longer patients have longer prostheses that can not always be accommodated in luggage. Which may be because the sockets have a large load capacity which has a negative impact on baggage space when traveling abroad, when traveling patients are often in need for several prostheses for various activities to be packed in the luggage. Patients often also prefer to disconnect prostheses for longer periods at lack of legroom to achieve a better sitting position.

There are major shortcomings in how the user can customize their systems for those situations they face. When users are expected to switch between the entire prosthetic system, they can experience situations where system design is perceived to be obstructive whenever they want be spontaneous

Stage of development

At the current stage a working prototype have been produced and mechanically and user tested for evaluation.

Build height

Current version have a height of 64mm

Conducted tests

During the development the prototype have been user tested, as well as mechanically tested in a UTM with a custom loading scenario.

Materials used

Main body made in Titanium Grade 5, smaller internal components in structural steel as well as ABS plastics for fairings.

What's the solution?

And how does it look?


The coupler is developed to fit with the female connector attached to the pyramid adapter at the socket. The male connector can then be connected directly to the other components.

Cosmetic fairings

The system is developed to work even if enclosed inside foam based cosmetics with silicone sleeves, as well as with 3D-printed cosmetics.

Internally enclosed components

The main function of the device is enclosed within the structure. With seven internal parts allowing for the quick release functionality.


Following achivements have been reached during this project




Filed patents


Units Produced


Awards won


Steps taken

Mechanical testing cycles


Which sports & activities have been tested with Hydra Coupler.


Gym Workouts
Lighter hiking


Everyday usage
Motor Cycling

What is the impact of the product?


Lowered cost

The implementation of the product could reduce cost of manufacturing prostheses for patients, as well as reduce the manufacturing time.


Ease of transport

The component allows users to just bring the specific components needed for traveling. Reducing luggage space and weight.


After installation there is no need for external tools for usage. Which allows the user for freedom of choice in any given situation.

One socket fits all

Allowing for usage with and without cosmetics allows the user to use every component with any socket, independent of cosmetics.



For more information please contact Martin Adelholt or through our contact form Here


Last updated: May 29, 2018

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