Process Book Low-Tech Rehab Fall 2011 Daniel Orbach
“Design a low-tech rock-climbing and hiking Prosthesis for an above knee amputee�
Table of Contents Research Sketching Validation Modeling The Design Exploded Views & Engineering
Let’s Talk About Amputees Active Amputees have a better quality of life relative to those who are less active
of amputees do 0-1 of the activities they did before the amputation
of lower leg amputees report moderate to severe pain while wearing a prosthesis
Barriers to sports participation for amputees: pain, embarrassment, and a lack of special organized programs for amputees There are over 1,000 Amputees coming back from the wars in Iraq and Afghanistan
70% of all amputations occur below the waist, and 39% occur below the knee
For every step you take, an amputee has to use around 1.5 times the amount of strength as you do. As the day goes on, the effect intensifies.
These facts were pulled from over 50 scholarly articles and interviews I read as part of my research. Citations available upon request
What is happening in the world of prosthetics now?
Prosthetics are becoming more high tech every year. Low-Tech options are largly falling by the wayside, but there is a huge need for extreme sport prosthetics, as only one knee currently exists, and there is no complete solution
2007: the first 3d printed prosthetic socket
2008: XT-9 extreme sports knee hits the market
2009: The 4th annual Extremity Games are stages. This was the first time the mainstream media covered the games.
2009: outside magazine published 7 articles about different active amputees
fall 2011: Innovation Magazine Issue discussing prosthetics at length
2010: OttoBock releases the second C-leg, it makes 1,000 calculations per second
2011: The VA builds a theraputic rock climbing wall for recovering amputees
What comprises a prosthetic leg? Protip: Though not visible, suspensions
are a critical part of a prosthetic. They help keep the socket on the leg, and often involve the user wearing a silicone “sock� as well as using air valves and belts for suction and security
Socket The part of the leg that interacts directly with the residual limb. Most amputee pain happens here.
Attachment point The point where the prosthetic is suspended from the socket
Knee/Calf Nowadays most knees are fully mechanized, complex structures. This is a computerized knee, and needs a lot of room for mechanisms
Ankle
Foot The foot is usually covered and made of carbon fiber and other composites
Many prosthetics don’t have an articulating ankle because they inrease the propensity to stumble
So what is out there now? Sport related prosthetics
XT-9 Extreme Sports Knee
Cheetah Leg by Ossur
Eldorado Z-axis climbing foot
pros
pros
pros
Absorbs and gives back energy waterproof the most durable prosthetic knee
Top of the line running leg lightweight
shortened foot the only foot on the market
cons
cons
cons
Doesn't articulate heavy adjustable only using special tools not a complete solution
not for use with climbing can't navigate uneven terrain expensive not a complete solution
no shock absorption foot is still forwards not a complete solution can't be used to hike
So excersize is critical for amputee rehabilitation, especially for our returning veterans. What kinds of prosthetics exist for what sports? Right Now, Specialty Prosthetics Are available for: Aerobics / Dance / Gymnastics Hockey Archery / Bowhunting Pool / Billiards / Snooker Baseball / Softball Photography Basketball Bicycling Skip Ropes Canoeing / Kayaking Sparring / Martial Arts Snow Skiing Fishing Swimming & Surfing Firearms Musical Weight Lifting Football / Soccer / Volleyball Wind Surfing Golf Climbing
A curiously relevent study
Comparing the energy expenditures of an above knee amputee in climbing a rockwall when put in five different prosthetic conditions When asked to subjectively rate their climbing experience with the different prosthetics:
Volume of Oxygen consumed during the climb (lower is better):
Climbing times, from fastest to slowest.
1: shortened prosthesis, foot backwards
1: shortened prosthesis, foot forwards
1: shortened prosthesis, foot backwards
2: no prosthesis
2: shortened prosthesis, foot backwards
2: shortened prosthesis, foot forwards
3: shortened prosthesis, foot forwards
3: no prosthesis
3: no prosthesis
4: articulated prosthesis, knee unlocked
4: articulated prosthesis, knee unlocked
4: articulated prosthesis, knee locked
5: articulated prosthesis, knee locked
5: articulated prosthesis, knee locked
5: articulated prosthesis, knee unlocked
But I didn’t stop there, I went to UCs rock wall, and climbed with a straightened leg.
Starting the Climb is not an easy task, it’s mostly arms in the begining since footholds are limited.
Getting over ridges is very difficult, because the straight leg cannot bend, or apply force to assist the climber.
on some occasions it would have been nicer of the straight leg was shorter, so the climber has a wider range of motion
near the top things can get tiring, because of the deadweight of the leg, combined with the stress on the muscles.
Interviews
Mike Lagerstrand
Patrick Taylor
A prosthetist at the VA
The head of prosthetics at the VA
“What you really need to do is keep this thing as simple as possible. Especially if they’re going to be wearing it for a long time.”
Clifford Robbins A prosthetist at J.F Rowley
“And actually for rock climbing you’d wanna make sure the suspension was good. You’d probably want a sleeve, with suction and a pin” Got to sit in on a patient fitting, and see how sockets are made
“You know, there really is a need. A big need. These veterans are coming home, and they want that outdoor experience.”
Andrew Meyer
An active above knee amputee
“I have the XT-9 Knee, and when I climb it’s great, but since it doesn’t swing hiking with it is horrible” “I try to stay as active as possible, and I’m actually doing some new things I never thought I could do.”
Photos from interviews
Trying a socket sleeve on my arm to see how tight the fit is. The amount of friction was far greater than I had initially realised
Taking a look at the JF Rowley workshop. Carbon fiber was everywhere. They still use many techniques most of us would think of as antiquated. They are in fact still used widely throughout the prosthetic world.
Photos from interviews A workstation for handcarving negative and positive socket shapes.
Taking a look at various prosthetics they had lying around the shop. One of which was ottobocks state of the art C-leg
Photos from interviews
Some of the equipment used to currently make prosthetics. There were just drawers filled with components
Photos from interviews
The equation of opportunity
Prosthetic Legs are getting more and more high tech Returning Veterans hike and climb as part of therapy. A climbing and hiking camp for amputees has recently been established There is no total solution for amputees who wish to both climb and hike Physical activity improves the QOL for amputees A need for a low-tech, low-cost rock climbing & hiking prosthetic.
Design Requirements
Durable The leg needs to be built out of standard prosthetic materials, but can incorporate extra reinforcment in certain areas. often times the simpler it is the more durable it will be
Comfortable The biggest reason amputees won’t wear a new prosthetic is simply because it isn’t comfortable. Extra pains will be taken to ensure this prosthetic is as comfortable as any.
Modular If this is to be used for both hiking and climbing, it should have a hiking mode and a climbing mode. However, Modularity should affect weight as little as possible
Lightweight
No one wants to climb with any extra dead weight. Making this leg as light as possible is paramount to its success.
Design Inspiration
Climbing Culture
I did my homework. A lot of it. After reading over 50 scholarly articles, and interviewing a myriad of professionals it was time to draw my heart out.
Rapid Ideation
Rapid Ideation
Rapid Ideation
Rapid Ideation
Rapid Ideation
After all this sketching and researching I figured it was about time to validate my ideas. So I narrowed them down into 3 concepts:
Concept One: The Lightweight
The simplest and lightest of all three concepts this concept would have up to 9 inches of telescoping motion, and potentially include a free swinging knee.
Hits The Simplicity Socket Bumper Height Change is Large Integrates With Existing Parts
Misses “Not As Visually Exciting” No Failsafe Suspension “That Shock Matters A Lot”
Concept Two: The Welterweight
This concept sits right in the middle of the spectrum. It utilizes a shock to absorb impact, but the suspension is not as extreme. This concept was consistently ignored during validation
Hits The Valve Placement Shock Absorber
Misses Too Much Mass Shock Limits Height Offset Shock Too Complicated
Concept Three: The Heavyweight
The most intense of all the three, this concept features a quadruple suspension system, and a protective rollcage for a heavy duty shock.
Hits The Suspension Fabric Lip With Pocket for Tools A Big Hit Aesthetically Rugged Overmolded Socket
Misses No knee Potentially Very Heavy Shock Limits Height Lots of Parts
Concept [X]: The Auxiliary
Prosthetics are complicated and tend to have a lot of parts. This page is an effort to simplify and help explain the final foot and socket direction.
The socket will ultimately utilize three forms of suspension. A sleeve, an air valve, and foam. The foam will also help guard against the effects of volume loss. A lamination process will allow for a simple construction, with all of the necessary parts
This two part foot was consistently succesful during validation. It has an inner, foot for climbing, with an outer chassis for hiking.A shoe won’t be necessary. The concept was green-lit by an engineer. However, this concept will end up being simplified for the final
Final Direction: The Lightweight Ultimately, this leg formed the base of the final design. it’s weight ended up being crucial in this decision. Another large influence was the fact that the leg did not need as much “protection” as initially anticipated. Though the leg would not stay this simple, simplicity remained a driver for the rest of the process
Validation: done. It’s time to get real and make some models. (I love sketching as much as the next designer, but sometimes you just need to see things in 3d.)
Models were made for the foot, calf, and knee. Many of the knee models were functional in nature, while the other models were mostly costmetic.
3D modeling iterations
Getting started on the 3D model was a bit daunting. Before deciding to move the shock from the calf to the knee, I built a base model, and began to experiment with different housings. This direction was eventually nixed. But It’s always good to show process!
3D modeling iterations
More nixed alias iterations. Unfortunately, they didn’t all end up being saved, but many of them were built against a human form, as you can see above.
3D modeling iterations
After working in alias for a lot of the back-end 3D modeling, the model was rebuilt in solidworks from scratch. Here you can see form studies produced in both solidworks and alias for various parts of the design. Test rendering was critical in determining the color finish and materials. Every model made was not only built to test the form, but to test the paint and metals as well
Full Scale Plot
After producing close to final geometry, full scale plots were made using orthographic drawings. These drawings were then compared to measure of man drawings, and adjusted to make sure that the prosthetic fitted the shortest woman all the way up to the tallest man
All of these models are great, but my product needed a brand to help tell its story. So I created one. Meet Tรถg:
so what is TOG ? Tรถg is a brand focused on creating experiences for amputees in an outdoor and active setting. It does this mainly by providing prosthetics geared towards outdoor activites. For this project Tรถg is producing a rock climbing and hiking prosthetic. Adjacent products might include a kayaking prosthetic, or a scuba diving prosthetic.
Branding Opportunities High End
outdoor
indoor
Low End
Visual Options
Form Cues
using raw materials, and employing a powerful on-product brand presence are some of the things Tรถg needs to do in order to become a succesful brand
All that process led to a final product. Allow me to introduce you to the Everest Leg, by Tรถg
socket is reinforced with plastic bumpers to increase durability
free swinging knee with a manual lock *
Total Estimated Weight is Less than 8.25 LB, this is in line with industry leading prosthetic legs slim profile 1 way valve helps make the leg easier to manage under clothes
*Calf allows leg to shorten up to 6.75 inches easy push button for shortening leg
durable titanium telescoping pole Foot connects using industry standard mechanics Carbon fiber foot has a rugged rubber outsole so no shoes are needed
Bungee cord acts as a safety in case the pole falls out *foot turns 180 degrees to climb, this climbing surface is engineered to take up to 2400 pounds of force
*This feature is a completely new innovation
Socket contains a ring of foam in order to counteract the effects of volume loss during physical activity. This is a feature unique to this product.
Rubber gasket protects assembly joint, and reinforces it as well
Shock integrated into knee column
Pole shortened 6.75 inches
Rubber coated steel can withstand up to 2400lb of force
Foam Insert for socket
ABS plastic bumber Laminated Carbon Fiber
Molded Plastic Air Valve Titanium Knee
Cast Titanium
IM Rubber
Rubber Coated Plastic Button
Painted Titanium Column
Steel Joint Rubber Coated Steel Anodized Steel Hardware Carbon Fiber PU outsole
Laminated Logos
Hike freely with the everest leg
2 simple pushbuttons on either side of the calf control leg length
A fully articulating knee allows the user to sit down for breaks as well as various prosthetic adjustments
An allen wrench is all it takes to lock the free swinging knee in place for a climb
"this design is better than a lot of the things people in the field have come up with" -Cliff Robbins (Prosthetist with over 20 years of experience)
"the foot on this thing is a really good idea. I mean really good. You should be proud" -Christina (Practicing prosthetist at JF Rowley)
"for someone in my position to sit here and see something this awesome, is really encouraging" -Andrew Meyer (Above knee amputee)