New Suspension Option

New Suspension Option for Transfemoral Amputees

The WillowWood One System, launched in April 2015, now provides transfemoral amputees a choice in suspension methods without sacrificing reliability and security.  The WillowWood One System may now be used as a suction socket.

Initially released for use only with elevated vacuum, WillowWood has been clinically testing the system with suction suspension for the past 10 months. The suction suspension version of the system is ideal for amputees who prefer less technical or complex options in their prostheses.

The WillowWood One System includes several components, such as a fabricless Alpha SmartTemp® Liner, a gel sock, a seal, and a removable brim, that work together to deliver reliable and secure suspension.

Certification is required to purchase and fit the WillowWood One System. For product and certification course information, contact WillowWood at 800.848.4930 or visit

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Prosthetic Advancement

Prosthetic Advancement Helps Father of 3 Enjoy Life Again

Josh Green has been an amputee almost his entire life. Born with his tibia, fibula, and femur fused together, he underwent a transfemoral (above-knee) amputation when he was only four years old. After being fitted with a pediatric prosthesis, he adapted quickly and less than a year later, was playing T-ball with his peers. “My parents didn’t treat me any differently than my brothers,” he said. “We all played sports and I played all through high school – golf, basketball and baseball. I was able to function.”

But as years went on, it was a different story for the Elyria, Ohio, man.

“The place where I got my prosthesis, whatever they supplied I wore. I never had a choice for anything different. I had a nylon belt that would hold the prosthesis to my leg. I was fitted with a suction socket once, but with the sweat, it always came loose. There weren’t any other options,” he said.

Not having a reliable prosthetic leg meant Green had to give up his job and restrict activities with his five children.

“I was a chef for 12 years but I had to give it up because I couldn’t do the long hours anymore; I had to go on disability and my kids had to get used to me not being able to run or play with them,” he said.

Things turned around for Green when a representative from WillowWood, a prosthetic manufacturer, happened to see him in the lobby of a health-care center. “I guess she could tell my leg was an older one. She invited me to contact WillowWood; they were looking for amputees to test a new socket. When they heard my story, I was chosen to be in the study of a new socket system, the WillowWood One.”

WillowWood, located in Mt. Sterling, Ohio, has been manufacturing prosthetic products and advancing prosthetic technology for more than 100 years. One such advancement by WillowWood is the LimbLogic® vacuum suspension system which was introduced in 2007. While LimbLogic® improved mobility for below-knee amputees, there wasn’t a similar system for above-knee amputees.

The Pathway to Making a Difference

WillowWood, in collaboration with The Ohio State University, a world leader in wound healing and tissue health, and The University of Akron, which has extensive experience with polymers, applied for and received a $3.7 million grant from the U.S. Department of Veterans’ Affairs Innovation Initiative to improve socket technology for above-knee amputees.

The goals were to give above-knee amputees a socket system that is comfortable, controls pistoning, reduces sweating, allows for a comfortable walking gait, and monitors and responds to activity levels of the user.

Civilian and military amputees were selected to be testers of the system. The group of 42 included males and females with activity levels ranging from basic ambulation to high activity.

Jim Colvin, Director of Research and Technology at WillowWood, explained the testing process.

”Sockets were evaluated by the prosthetist and amputee using traditional methods of clinical observation and subjective assessment. In addition, data was collected through a variety of methods,” he said. Those included:

  • Limb temperature and perspiration collected in controlled experiments to assess the temperature and perspiration reducing capabilities of the new Alpha SmartTemp®
  • Skin health and circulation measured using in-socket and out-of-socket methods, including surface electrical capacitance, cutometry, transepidermal water loss, hyperspectral imaging, laser speckle flowmetry, laser doppler flowmetry, and transcutaneous oxygen measurement.
  • Internal socket pressure and motion data obtained using the Communicator (a tool developed as part of the project).
  • Gait data collected with a GaitRite mat.
  • Written feedback gathered from the users at regular intervals.

Green, along with other amputees who were using the product, found that with the new WillowWood One socket system, they had a secure connection between their residual limb and the prosthesis (no slippage), improved thermal control (no excessive sweating), greater range of motion, and no need to constantly readjust the prosthesis.

“After the first fitting, I came home and played kickball with my kids,” Green said. “They were really excited to see me run and play, something I was not able to do for years.”

“It’s helped a lot, it’s comfortable, it forms to you, it always sits perfectly and it’s never lost connection to my residual limb.”

Challenges and Solutions

As with any comprehensive research and development project, there were challenges.

“The socket design is different from previous designs, so there have been challenges educating both amputees and prosthetists and getting some amputees to accept the design initially. Experience with the socket allowed them to understand the benefits and to become comfortable with the use of the socket,” Colvin said.

“Obtaining limb health measurements inside the socket was a challenge that was overcome by developing a unique sensor holding system. Development of the optimal liner polymer was difficult and involved considerable benchtop and clinical testing of a variety of formulas,” he said.

After 26 months of development and testing, the project concluded with three key innovations.

The first is an improved version of WillowWood’s LimbLogic® vacuum suspension system that has been adapted for transfermoral applications. A side-mount design allows a more anatomically correct knee center and aids in sitting. The software also was improved for better control and diagnostics.

The second is the Alpha SmartTemp® Liner that regulates skin temperature by incorporating Outlast®, a Phase Change Material (PCM) that stores and releases thermal energy as it transforms from a solid to liquid and back to a solid. The result: hardly any sweating, even on the hottest of days.

The third is a sealing system featuring a soft silicone brim and an internal silicone membrane to maintain a secure comfortable seal that is protected from punctures. The flexible brim and seal allow for an increased range of motion and additional comfort for the amputee through all daily activities.

Quantifiable Results

During clinical testing, amputees repeatedly commented that they could put the system on at the start of their day and no longer needed to adjust their sockets repeatedly throughout their day. The second overwhelmingly reported feedback was that the airtight seal for the system did not break. Amputees could comfortably move from sitting to standing, walk, run, ride a bicycle or motorcycle and did not experience any movement of the socket.

Users report that they no longer have to remove the socket during the day to wipe away sweat, they participate in activities that their previous prostheses did not allow them to do, and all of their daily activities including something as simple as sitting in a chair are much more comfortable.

Wearing a prosthesis and having to worry about it staying in place is a common concern among amputees, who have to adjust their socket to accommodate volume fluctuations – walking in a prosthesis can lead to a temporary reduction of fluid in the residual limb and sitting for an extended time can lead to fluid retention. The build-up or loss of volume results in the socket fitting too tight or too loose.

“It’s awkward enough being an amputee, but even more awkward when every two hours you have to find a bathroom to adjust the fitting,” Green said. “With WillowWood One, it’s a one hundred percent difference in comfort and security.”

Green concluded: “The people at WillowWood have helped me out more than they know. Now I’m an active, stay-at-home dad with my two-year-old and starting this year, I’m the JV coach for basketball and baseball for my older boys. I’m really excited for this new opportunity. I love that I get to see my kids so much.  I also have been umpiring baseball games for the local traveling team. It’s not a luxury to be able to function!”

Results of the project have been published or soon to be published in peer-reviewed journals including Orthobode, a publication of the Orthopedic Foundation for Information Netherlands ; JPO, the Journal of Prosthetic and Orthotics ; and JRRD – Journal of Research Rehabilitation & Development.

So far 16 papers have been presented, with six more planned at scientific meetings including the International Society of Orthotists & Prosthetists (ISPO) World Congress 2015 in Lyon, France; the American Academy of Orthotists and Prosthetists Scientific Symposium in New Orleans, and the American Orthotic & Prosthetic Association National Assembly in San Antonio.

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A Successful Collaboration

A Successful Collaboration to Improve Transfemoral Sockets

Transfemoral (TF) amputees face numerous disadvantages compared to those with a transtibial (TT) amputation. In addition to the issues that are common to all lower limb amputees, such as volume changes and perspiration, TF amputees also experience reduced comfort and range of motion due to existing designs in which a rigid plastic socket extends high on the limb. Adequate suspension of these sockets is also difficult to achieve due to the lack of space available on the thigh for accommodating the external seals that are used successfully in TT suspension.

Faced with these challenges, transfemoral amputees can be forgiven for having low expectations when offered the opportunity to test a new design. However, amputees who have been fit with a new transfemoral socket concept from WillowWood have made statements such as “The day I got this, I ran for the first time in three years;” “For the first time in 35 years, I can vertically jump;” and “I’m living again.” What new technology has caused such a reaction, and how did it come about?

The project began in early 2011 when the U.S. Department of Veterans Affairs announced an Innovation Initiative (VAi2) to improve the fit, function, and comfort of prosthetic sockets for transfemoral amputees. Because WillowWood’s engineering team had already been working on some concepts that coincided with this goal, it made sense to apply for this grant; but to make the proposal even stronger, WillowWood approached The Ohio State University (OSU) and The University of Akron (UA) to join the project as collaborators. Ohio State is a world leader in wound healing and tissue health; UA has extensive experience with polymers. Together, these three entities submitted a concept paper in April 2011 that described a 4-pronged approach:

1) Development of an internal seal for a TF socket.

2) Improvement and adaptation of WillowWood’s LimbLogic® vacuum suspension system to TF applications.

3) Stabilizing the temperature inside of the prosthetic socket through the use of new thermally enhanced materials and structures.

4) Research to establish the optimal integration of these new technologies and their efficacy.

In August of 2012, WillowWood was selected to receive the VAi2 grant, and work began in earnest. UA evaluated existing liner and socket materials, and OSU conducted outcomes research on various existing socket designs. WillowWood used their findings in the development of the socket system, after which OSU and UA evaluated the new design. Additional collaborators from industry, such as Outlast Technologies, were brought in along the way.

Throughout the process, the internal WillowWood team met weekly, an Outcomes Measures group held a weekly teleconference with OSU, and a Cooling System group held a weekly teleconference with UA. WillowWood’s team also visited OSU and UA to participate in some of the testing efforts. The team published monthly reports and shared documents using BaseCamp, a web-based project management and collaboration tool. Face-to-face meetings between collaborators, VA personnel, and amputee test patients were held each quarter.

The resulting system incorporates the following elements:

An internal socket sealing system featuring a flexible polymeric sealing membrane attached to a flexible inner brim. This system accommodates proximal limb motion while maintaining a secure, comfortable seal that is protected from punctures.

A vacuum system that allows better positioning of the knee components for optimized knee center height; easier release of vacuum; reduced noise; adaptive pressure regulation based on socket conditions; and tracking of socket conditions and system usage.

A liner that regulates skin temperature by incorporating Outlast®, a Phase Change Material (PCM) that stores and releases thermal energy as it transforms from a solid to liquid and back to a solid.

A lower trim line that increases comfort for the user without sacrificing suspension.

The system has been worn by dozens of test patients, all of whom provided valuable feedback to help refine the design along the way. Users report that they no longer have to remove the socket during the day to wipe away sweat; they participate in activities that their previous prostheses did not allow them to do; and all of their daily activities, including something as simple as sitting in a chair, are much more comfortable.

There were many challenges along the way, such as contract negotiations, gel formulations, socket fabrication, sensor accommodation for in-socket testing, and thermoconductivity test methods. The key to successful completion of the project was for all parties to remain flexible as they worked to solve each issue. Each entity contributed key achievements in their areas of expertise to produce a significant step forward in transfemoral socket technology.

Copyright © 2015 The Ohio Willow Wood Company

All rights reserved.

PN-2389-A 12 MAR 2015

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