Frequently Asked Questions

Martin Bionics was invited by NASA to transition our work in fabric-socket technology into the Space Program to help NASA connect exoskeleton robotics with astronauts in a more comfortable way. Our success on that program lead to being invited to play a role on two additional exoskeletal robotics programs with NASA, where we lead the physical man/machine connectivity aspect of those projects. Martin Bionics created and discovered some fascinating new materials and methods during those programs, which we have since transitioned into a new way of fitting clinical prosthetics. The specific mesh material of our Fabric Inner Socket is made of the same unique blend as was used in the NASA programs. It’s design enables it to very effectively conform to the 3-dimensional body, yet is incredibly lightweight, durable, and breathable.

The dynamic and conformable materials used in the Socket-less Socket™ system are incredibly durable and are designed to give a long life-expectancy. The SwingBrim™ webbing for instance is designed and rated for close to 5000 pounds of force, which is made of a material that is similar to a seat-belt, but thinner. We see very few durability related issues, but if something were to break, our unique modularity allows the socket to be repaired quickly and easily and is often field serviceable even if away from your prosthetist. More importantly, the socket should remain comfortable for much longer than a traditional socket, as the user-adjustable conformable materials match the socket to the user, versus the user’s limb having to match to a static piece of plastic. The human body is very dynamic, and making the socket’s fit dynamic as well provides a long lasting comfortable socket.

Yes, the Socket- less Socket™ is simple to donn in sitting or in standing, and does not require pushing or pulling soft tissue into a contained bucket as conventional sockets require. If an end user is able to tie their shoes, they should be able to donn the Socket-less SocketTM designs with ease.

Yes, the Socket-less Socket™ works excellent with short limbs to long. We’ve successfully fit several above the knee users with femur lengths as short as 3” to 4”. Some of these users could have been fit as a hip disarticulation level since the femur was so short. But since we can so effectively capture the underlying femur through our Floating Femoral Pad, it can provide much greater limb control than a conventional rigid bucket socket.

The Socket-less Socket™ accommodates for a large amount of volume change. In some cases a ‘sock-ply equivalent’ of 10+ ply up or down will still maintain the same comfortable feel. The comfort of our sockets does not change with volume change as in conventional sockets. In conventional sockets, the comfort of the fit degrades over time as the limb size changes. The Socket-less Socket™ however should largely remain comfortable up until the time a new socket is fabricated.

Conventional sockets are rigid, heavy, and trap heat. The Socket-less SocketTM designs uniquely offers user-adjustable volume accommodation, is lightweight, and breathable – qualities that most amputees desire. It has been successfully fit to all limb types – Short limbs to long, large limbs to small, geriatric to athletic, and on those with a lot of volume change to those without volume change. We’ve found that even those who do not fluctuate in volume (less than 2 ply per day) love the ability to micro-adjust the socket fit in real-time.

The user should not experience discomfort at the brim level, and more specifically at the proximal end of the anterior medial strut near the Adductor Longus Tendon, but if they do, check each of the following:

A. Make sure the proximal end of the anterior medial strut is positioned directly in line with the Adductor Longus Tendon, with its proximal swivel directly over the tendon. Also make sure that the blue foam arch pad is positioned over the swivel.


B. If the proximal end of the anterior medial strut is too high, raise the distal AirHammockTM receptacle in order to apply additional distal support and slightly raise the user out of the socket. This will be more effective than attempting to lower the brim level.


C. Make sure that the angle of the anterior medial strut it not too straight up and down, but rather flows in line with the natural limb shape angle. By widening out the socket at the brim level through a slight angle change to the anterior medial strut will put less medial/lateral pressure at the brim level.

The Socket-less SocketTM uniquely conforms around the limb and allows for sensitive areas like the distal femur to remain outside of the socket with no rigid structure to hit. The user should not experience distal femur pressure, but if they do, check each of the following:


A. Make sure the posterior lateral strut is positioned behind the distal femur, with the distal femur resting in between the posterior lateral strut and the floating femoral pad. The distance between the strut and the pad should be as close as possible, while still allowing the distal femur to remain in between. If the distal end of the posterior lateral strut is too close to the centerline of the socket (too much compression into the limb) it may cause excess pressure. During the fitting process simply move the distal end of the posterior lateral strut one to two holes outset by adjusting the position of the attachment point into the lollipop base plate of the fitting components. Typically also make an angle change to the strut to allow the proximal end of the posterior lateral strut to remain with its same contouring to the body on its proximal end.

B. Containing the limb tissue appropriately is one of the most important elements of a well fitting socket, and can result in distal end discomfort if the limb is not supported correctly. Make sure that the end of the limb is supported in the AirHammockTM distal receptacle with the correct amount of distal pressure for that user. Circumferentially the limb should also be supported, and adding tissue management elements like more AirHammockTM petals, changing to a gel liner with more matrix, or adding a thermoplastic inner socket can help contain and control the limb tissue and eliminate distal pressure. See also the ‘Tissue Management’ section on page 6.


C. Some users limbs are not able to tolerate micro-movements between the femur bone and the soft tissue that surrounds it upon weight bearing. If better supporting the limb tissue through ‘Tissue Management’ (page 6) are not effective, consider using a more traditional distal containment through fitting the SwingBrimTM or cX-HybridTM designs instead of the full cXTM. This is typically a very effective path for the few users who can not find distal femur comfort in the full cXTM system.

The Socket-less Socket™ is designed to provide long lasting durability and comfort.  Its materials are designed to hold up to high-activity users, and the conforming nature of the materials allow the socket to match to the underlying body every time it is donned, allowing the socket to remain comfortable for longer.  The brim material for instance is made of high-strength webbing, similar to seat belt material, and is rated at nearly 4,000 pounds.

In conventional sockets, the carbon fiber lamination and inner socket materials are great heat insulators.  Conversely, the Socket-less Socket’s™ open frame design allows the limb heat to dissipate, making for a cooler socket environment.