April 10 2018 - Trying out a Bionic Knee

I just got home from the Prosthetist. I am wearing a new Bionic Knee. It is a Genium, made by Otto Bock.

During the fitting of the knee, the Prosthetist found that neither of the feet I have been using will work, because the knee is to long. So they had to temporarily give me a old, straight, cheap plastic foot.

The Physio lady and I walked around a bit so I could get a feel for it, But I never felt safe with it. Every step it feels like it is collapsing. This "collapse" is only for a few degrees. But that same feeling with my Total Knee 2100 means I will fall to the ground.

 When I step forward, the Genium is designed to hit the ground at a 4 degree knee bend angle. As soon as my body weight is put on the knee it gives slightly until the computer locks the knee from bending further. This is supposed to give a slight "give" and therefore be softer on the stump. But as soon as I try to walk, it goes to 0 degrees with a clunk. There is no resistance in going from the 4 degrees to the 0 degrees.
The Physio lady said to not push back with my stump.  With the 2100, I have to push back to make sure it is locked. This Genium should not require that. But how can I ever walk forward without pushing back with my foot to push me forward. If I walk backwards with the Genium, it feels much better than walking forward.
So as I walk, the Genium goes click, thunk, click, thunk, click, thunk.

I am battling getting used to this knee compared to my Total Knee 2100. I am used to making positive that the knee is locked before putting any weight on it. The Genium is supposed to do that thinking for me, so I need to learn to let it do what it is supposed to do.

With my 2100 everything seems "Black and White". The knee is totally floppy, or the knee is locked. The Genium is all "Grey". It is kind of, sort of, floppy, or kind of, sort of, locked.

 This Genium knee has 3 accelerometers, and 5 sensors. It detects if I am standing still, sitting, falling, and the speed I am walking.

If the knee detects that there is weight on the leg, and it is straight, it will lock straight. Like when I am just standing.

If the knee is bent in one position for a short period of time, it will lock in that position. Like squatting.

If it detects I am trying to sit, then it will give resistance to the knee bending of about 30 kg (60 pd) to help lower me into the chair.

If the knee detects I am sitting for more than 2 seconds, it goes into power saving mode, and supplies no resistance to movement.

On walking up stairs, if the knee detects a sweeping backward motion very soon after a stance phase, (I have to learn to signal the knee with this action) then the knee thinks I am going up stairs, and it will go all loose until it detects pressure while bent. Now it thinks the prosthetic leg is on the next step up, and will lock in that position.
It does the same thing when walking up a steep slope.

When walking down a steps, or a steep slope, it will act similar to when I am sitting down, and apply resistance, so I can sort of ride the knee down the slope or steps. Going down steep slopes is great. I can do that much better today than ever before with any knee. This down slope walking should speed up my ParkRun time significantly.

I definitely rub people the wrong way. The Physio lady and the Prosthetists seems to just want me out the door. So I left, with the knee not performing anywhere near what I think it should.

As I was leaving, I met the guy that works there that is a double leg amputee. We chatted for about 20 minutes. He is full of useful knowledge, experience, and information.
He says that he tried the Rheo3 (Ossur's Bionic Knee) and the Genium, and didn't like either one. He says he likes to be in control of things, especially of his prosthesis. He says the Bionic knees take to much of his control away. They are in charge of how he walks, not him. He asked me what my profession was before I lost my leg, and I said that I was a pilot. He said that he would be surprised if I liked relinquishing control of my walking to a computer.

He said that first time amputees like the Genium, because it makes learning a prosthesis much easier. He also said that it seem to be liked by non-technical people better than technical people. That is sort of the opposite of what I would have thought. I thought that geeks and nerds would love all the AI and computers.
But then, most geeks I know like Linux and the command line, and the non-technical people I know all like friendly, easy Microsoft.

He also said that when he does rough terrain, he uses walking sticks. The ones like ski poles. He says the extra balance provided, makes him much faster. All the energy used to run the race is still from him, so he doesn't care what others think. He usually doesn't use a cane, crutches, or walking sticks because they are a pain when he isn't walking, or using them. But he says that anytime he can conveniently use a cane, crutches, or walking sticks, he does.

I just read this on line:
The highest of high-end prosthetics right now is the Genium knee, "the Maserati of microprocessor prosthetics,". Ottobock developed the Genium with the Department of Defense, hoping to let soldiers with lower-limb amputations return to active duty. It's waterproof, dust proof, saltwater resistant, and it runs silently. The Genium's estimated cost is around $120,000.

I think the cost has come down quite a bit.  The Genium is now about R850,000, which is only about $71,000.

The Genium comes with a nice charger for the batteries. It holds on magnetically, and works through clothing. The battery should last about 5 days.

I have another appointment on Friday. Then I'll try to get them to fix the knee, and I'll get the download for Android to control and program the knee with blue-tooth from my phone.
Till then I'll be walking on a $71,000 knee that goes click, thunk, click, thunk, click, thunk.

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April 6 2018 - New Physio Lady.

On Tuesday I went to a new Prosthetist. There they have on staff a Physiotherapist lady that specializes in amputee walking.

Today I had an appointment with her. We talked for a bit, then went walking around the complex where their office is. The complex reminds me of a Collage campus.

She had a route to walk, that had many of the obstacles I have trouble with. We walked up some steps, then up a long slope where there was some loose soft gravel. Then we walked more stairs and slopes, and got back to the office an hour later. I was very tired.

She showed me how it is easier to go up steps if the good leg goes one step past the prosthesis leg on the way up. It was counter intuitive what she said, but after a few times up and down the steps, I could see her point. I need to work on steps a lot.

Then we did a long steep slope. Up and down. I was more interested in how to do slopes quickly, than how to do them pretty and normal. She showed me a quick side bunny hop for going down slopes. It is definitely faster than how I currently do slopes, but it uses a lot of energy.

We then went to a soft gravel parking lot. I tried many ways to walk on the soft gravel. The solution to walking on gravel and soft sand is....don't try to walk on gravel and soft sand!

I then mentioned how when I stand talking for a long time, my good hip starts to hurt. She said it was because my "blah blah blah, was to tight on the "blah blah blah", and it forced my "blah blah blah" to pull. So I need to change my long term stance to put much more weight on the prosthetic side. I tried her way, and it helps.

The best thing I learned today was getting up after a fall. I showed her how I do it, and she said that my way, is one way, to get up, but it require a lot of strength. I agree, because when I fell on the last Park-Run, I was already tired, and it took great effort for me to get up. I start on my stomach, but my way means that any weight I put on the prosthetic leg is on the toes, and therefore the knee will not lock. With the prosthetic knee not locked, then all the strength to rise must come from my good leg.
She showed me another way, that is slower, and looks silly, but requires much less strength.
If you sit on the floor with your legs in front straight, then your toes point up. If you lie on your stomach, then your toes point down. She showed me to start on my stomach and do the splits as far as possible. The toes gradually point more up (less down). At 90 degree splits, the foot is parallel to the ground. Now if I push backwards with my hands, the prosthetic leg heel takes the force. NOW the knee will lock, and I can push my bum up high and slowly stand with legs far apart. Then shuffle till both legs are together.

We got back to the office, and I was standing, and she said I should sit.
I told her how when I finish a long walk, as soon as I sit, my stump starts to hurt, and it throbs painfully. I then either stand again, or take the leg off. The leg will not come off easy, and it take a huge, long, effort to free the painful stump.
She says she knows what causes that, and fetched one of the prosthetists. He said that on the top, inside of the thigh near the groin, is where the artery and veins come into the leg. The artery is deep, but the vein is near the surface. My socket presses to hard on the vein when I sit, and the blood trying to escape the stump is trapped. This makes the stump swell, and throb. He says the socket should never press in that area, and I either need a new socket, or I need to grind or cut the offending parts away.
As soon as I got to the car, I battled to remove the socket from my throbbing stump. Once the socket was off, the pain was gone in seconds.
Once home I took my Dremmel tool and cut and ground off about half a centimeter all across the front inside of the socket. Now I need to trim the plastic liner.

I was hoping to get to try a new Bionic leg today, but it looks like only next week.

Tomorrow is a Park-Run. I want to try the new venue. I am a bit worried because I had a rough day today, and yesterday I walked 5.5 km, and the day before was about 2.5 km. I wish I had a full day to rest before the Park-run.

I also bought new Park-Run socks, and new insoles for my good foot shoe.
I hope they give me good luck tomorrow.
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April 3 2018 - Going to a Different Prosthetist

Today I decided to try a different prosthetics company. The prosthetist I have been going to since my amputation, seems to be trying less hard for my business than he did before. I have no specific complaints about any of his work, so maybe I just wanted a change.

I have been walking about 12km a week, mostly just to the shops for coffee. A few weeks ago I tried a local ParkRun. Park Runs are 5 km run/walks. There are athletes that finish in about 30 minutes, and fat, old ladies pushing a baby carriage that finish in just under an hour.
My fastest two leg ParkRun time was 35:39. My fastest time since amputation was a 1:24:48.

Last week I did a ParkRun in 1:56:19. I was exhausted and very slow. The terrain was very uneven the entire race. Uneven terrain means that the leg will sometimes unlock when I don't want it to, and sometimes will stay locked when I need to bend it while swinging it forward. Uneven terrain require me to concentrate on the ground immediately in front of me, where the prosthetic foot will land. This is not fun, and requires total concentration.

This is the foot I have now. An Ossur Vari-Flex. All the prosthetists I have talked to, say this is the foot of choice for most amputees.

I have always felt that the solution to uneven terrain is a flexible ankle. My Vari-Flex has a zero flex ankle.
Last year I borrowed, for 2 weeks, an Ossur Proflex ankle. It has hydraulics in the ankle so the foot can move the toes up and down to match the terrain.

It made uneven terrain a bit easier. It made slopes a bit easier. I would gladly have paid a few thousand Rand for that ankle...It was R87,000. Definitely not worth that much to me.

Today I called around to see if any other Prosthetic companies have any ankles to loan me. One place sounded much better than the others, so I drove there. They have a 2 hour evaluation exam and test, that is done by a Physio lady, and a prosthetist.
They are very modern, and proud of their technological approach to the prosthetic business. One thing I liked very much about their methods was they insisted on real world conditions.
My old prosthetist did all his alignment on a flat floor. I always felt that he could get it perfectly set up in that room, but it was all wrong before I even got out to my car. These new people first aligned everything on a flat floor, then took me outside to the real world. Steps, slopes, loose tiles, and rocks.

They strapped a small electronic measuring device on my prosthetic ankle, then made me walk supper fast for 6 minutes. This device measures acceleration, impacts, distance, cadence, and stride length. They also had video cameras to record me walking from all sides.
We studied the videos and the computer printout from the device after my walk.
They both said that my foot problems seem to be knee related. I told them my knee was fine, and the problem was lack of flex in the ankle.
I had to be careful, because these people seemed to know what they are talking about, and I always think I know everything.

While they were doing computer things, I chatted to a double above knee amputee. He works at a disabled children school. He told how he puts his single, above knee amputee kids on a pure straight leg with a J type carbon fiber running foot. He says that the kids run much faster over uneven terrain without any knee at all. He says the knowledge that they won't fall makes them go much faster than having a very expensive knee, that may make them fall.

This Para-Athlete runs with no knees. It looks funny, but he doesn't fall, and is very fast.

The prosthetist and the Physio lady both said that I may be faster on uneven terrain with no knee. I need to think about that.

They both said that I need more push off (energy recovery) in my prosthetic foot. They found an old Fillauer All-Pro foot and put it on my leg. It looks like this.

We then did the 6 minute fast walk with the measuring device strapped on. My stride was longer, and I was a bit faster. They say that it should have lots more give and flex on uneven terrain. They loaned it to me for a week.
Tomorrow I will go to one of the ParkRun venues near me that has rough terrain, and give it a try.

When I was done, and getting ready to leave, a lady came in. She was an above the knee amputee from cancer, so we had a great talk. She is getting a loaner knee. The top of the range Bionic knee from OttoBock. She was excited. The OttoBock guy said his job was to put as many people on OttoBock products as possible, even if it was just for a week or two. He said that he had another loaner that he wanted me to try out. It is a super Bionic knee. Lots of Artificial Intelligence in that knee.  Here is what it looks like:

If the actions of the knee fit one of many event criteria, then it thinks you are tripping and it takes corrective action.
It senses when you are standing still and will lock the knee. It senses when you are sitting, and goes slack. It senses if you are walking fast, and varies the resistances to match. It is programmable via blue-tooth, so you can change program profiles via a cell phone. You can read more about it here..

https://www.ottobockus.com/prosthetics/lower-limb-prosthetics/solution-overview/genium-above-knee-system/

A very fancy machine, but it costs almost what my house, and my car together are worth.

I will go back to these people in a week, to return the foot I am trying out, and maybe the OttoBock guy will have dropped off the Genium knee for me to do a 2 week trial.

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Oct 10 2017 - Am I becoming a Chicken/Fraidy-Cat?

My whole attitude to life has been gradually changing for a few years now. I think more due to the loss of the leg, than from the cancer.
I am seeing the "Black Swan" philosophy in many aspects of my life.

I recently got food poisoning.
A month of wonderful, home cooked, healthy, meals is not worth one bout of food poisoning. Food poisoning, harmed me more in a day, than healthy eating for months could possibly benefit me. I would be healthier eating from MacDonald's everyday and NOT getting food poisoning.

 Visiting a friend and getting lots of attention and caring, would be negated in a one second fall down their stairs. A fall could break an arm or leg to make crutches and a wheelchair unusable. That means months in a bed. I don't think a few months of love and caring are worth that risk. I would rather be in my safe home, in my safe wheel chair, than taking small risks, that have such super consequences. There is the desire of safety, in all that I do.

It used to be that the pluses of life were balanced by the negatives in life. It was worth doing exciting things if the worst that could happen was proportional. Life was in balance.
Now I see the positives in life as being minor, and the negatives as being huge.
A month of enjoyment playing with kittens, is not worth once, tripping over one, and falling.

Some people will act super concerned about the health of their children, spend big money on car seats to protect them, buy the safest car, and the best medical care money can buy, and yet, text while driving. In one second they can do more to damage the future of their supposed loved ones, than a whole life of caring and love could ever make up for. Their "love", is false love.

I would gladly forgo the positive pleasures of life, for the absence of the negatives of life.
The Buddhist philosophy, is of minimizing both the peaks of life, and the valleys.

I think about statistics of falling while using my prosthetic leg.
If the prosthetic is reliable 99% of the time, then I would fall every 100 steps.
If the prosthetic is reliable 99.99% of the time, then I would fall every 10,000 steps. That is only one day of walking.
99.999% reliable is a fall every 10 days.
99.9999% reliable is still a fall every 100 days. A broken arm, or broken leg every three months is un-acceptable to me.
Stairs, kittens, uneven ground, carpets, and wet floors change the percentages to make me want to just stay home in my wheel chair.

I seem to have made peace with the cancer. Death no longer scares me, like it did a year ago.
Injury, or falling, however, terrifies me.
I am sure the psychologists would have lots to say about that.

How unlike the "Me" that I used to know..

July 10 2017 - PET scan relief

After visiting the oncologist and the surgeon, the consensus is that the PET scan shows a clear body, free from any sign of cancer. 
The bright spot shown on the PET scan, in the inside groin area, of my stump, is most probably a torn muscle, NOT a tumor. :-)
Angiosarcoma does not usually metastasis to muscles. It will first go to lungs, liver, and kidneys.
A PET scan shows fast cell growth, like a tumor, or a torn muscle.

I spent a few hours with the prosthetic guy. He has lately been on some courses to learn about  "Elevated Vacuum" prosthetic systems. He wants to practice on me.
I'll get to tryout some expensive prosthetic hardware. The leg he wants me to tryout costs about $100,000. I hope I don't like it, because if I do, then I'll be trying to borrow that money from someone.  Actually I have no intention of ever paying it back, so it would be more of a "gift", than a loan. :-)

Elevated vacuum systems are another way of attaching the prosthesis to the stump. There is a seal between the socket, and the stump. A vacuum pump that sucks the air out from between the two. This makes the stump swell and form a perfect fit inside the socket. It is supposed to make the proprioception (feeling of position) much better. 

One downside I see with a system like that, is that putting the prosthetic on, and removing it, is a much more complex and time consuming procedure. 

Another problem is that the vacuum pump is battery driven, and needs recharging daily.

I look forward to trying the system, but I feel that reliability of a pure mechanical system may suit me better than the electronic systems. I feel the same regarding the new bionic knees and ankles. It is hard to beat the reliability of stainless steel, titanium and carbon fiber, when compared with batteries, motors, and electronics.

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June 22 2017 - Third PET scan

Today I went for my third PET scan.
The diet was followed perfect, and I was looking forward to a clean scan. I packed an egg sandwich to eat after the scan.
I drove to the PET scan place, arriving at 10:00 and did the whole procedure of injections, pills, and drinking peppermint tasting fluid.
I took my prosthetic leg off while there, and just used crutches.

I did the scan, then she said she wanted to re-do a section. So I ended up doing a total of 40 minutes in the tunnel.
Then they told me to go wait in the cool down room because I was too radioactive to be near anybody for an hour or so. Normally they allow me to eat then, but the lady said no food. About 20 minutes later, she said the Doctors wanted another partial scan.
So I went back into the tunnel, but this time it was only for about 10 minutes. They just did my groin area.

Then I went back to the cool down room. They said I could now eat.
After eating, I started to put my leg on, to go home. Then the Lady told me to leave the leg off for a bit longer. After another hour she came in and asked me to follow her on crutches, to the ultrasound room.

There they did an ultra sound probe of the area next to my groin on the stump. The cute ultrasound Lady said the area in question was next to, the groin lymph node.

After 10 minutes she had a pile of picture paper on the floor. She picked them all up and left. About 20 minutes later, she came back with a doctor. He did another 10 minutes of ultrasounding my thigh, and he produced another pile of paper pictures. They both left with the pile of pictures, and told me to go wait in the cool down room.

About 10 minutes later a lady told me I could put my leg back on. They they came and gave me a big sealed envelope and told I could leave now, and me to give the envelope to the Oncologist. They said that it takes 3 or 4 days before the pictures are interpreted and the report will be sent to the Oncologist.

On the way home I felt depressed, so bought a pizza.

At home I looked at the CD. All images are in DICOM (Digital Imaging and Communications in Medicine) format.
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June 23
It was not easy to see the DICOM images. I had to use GIMP (Graphic and Image Manipulation Program) to convert them to png format.
 Here are 2 of the PET scan pictures.

 It is easy to see what the problem is. On the groin muscle is a bright spot on the PET scan photos.
The bright dots above it are my balls, and the big ball above them is my bladder.
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Today I also spoke with my prosthetists. He made a cast of my stump almost 5 weeks ago. I wondered why things are taking so long.
He has been going on courses to learn a new system for prosthetic attachment.
Normally, like with mine, there is a seal, and a one way valve, that allows air out of the bottom of the socket when the stump is forced into the socket. This forms a suction in the very bottom of the socket, and that keeps the prosthesis from falling off.
With this new system, the seal is very high on the stump, and a small vacuum pump keeps the whole stump under a vacuum. This is supposed to keep the volume of the stump the same, and force the sides to be in contact with the socket. This is supposed to give greater feel, and less stump shrinkage through out the day.
Until very recently this system has only been available for below the knee amputees.
The brochure says it is for people that:

need volume management

require improved socket fit and comfort

benefit from increased proprioception and enhanced gait symmetry

need added safety by eliminating/reducing pistoning 

Well, I have need of all of those. As usual, they want the price of my house for the vacuum system.

One company also has a new foot/ankle system that allows walking on uneven ground.

Again big prices. Add to that a good new knee, and the total for a new leg will be +- $155,000 or  R1,900,000

My prosthetists say he is trying to get a loaner vacuum rig so he can practice building a system. He wants to learn on me. He also wants the medical aid to pitch in for most of the cost. I may have to also add some money.
All this is very exciting for me........
But now I have a shining spot on my PET scan pics. :-(
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June 11-14 2017 - Biopsy results, Park Run venues, Army amputees

June 11
Park Runs are 5 km run/walk/strolls for the family.
For more info, see my May 28 2016 blog about Park Runs.
My favorite nearby one at the Voortrekker monument closed down. It was all on tar roads.
There are usually many baby strollers, and dogs on leads. There are 3 new Park Runs to replace the one that closed down. All three are on rough terrain, and are two lap races. They all say that the terrain is not suitable for strollers, or young children.
Last week I walked one lap of the Bronberrik Park Run venue nearby. It had 3 streams to cross, and a very steep hill. It took me 1 hour 6 minutes to walk the 2.4 km. The up and down slopes slowed me WAY down.

Today I went to another new Park Run venue at Laudium. It is on a large sports ground, and has many 2 meter high berms around the various cricket fields. I zoomed around just one lap.It took me the exact same time, 1 hour 6 minutes and the distance was 2.5 km.
Again, the up and down slopes were the main time killer. Walking up a 2 meter berm, and then back down the other side is so hard for me.

A big reason NOT to run these Park Runs is the fact they are 2 lap races. Most people finish in about 45 minutes, and they usually stop timing after an hour. That means that every single person running the Park Run will lap me. There is no room to pass people in many sections, so I would end up delaying many, many people if I competed in these races.

So I am thinking about doing my own Park Run at these venues, on a Tuesday or Thursday. I need the exercise. I will miss the atmosphere of the real Park Runs though. :-(

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June 12
Today I went to the surgeon to have my stitches removed.
She said all looked great, and the biopsies were good news. Both tumors were benign Basil Cell Carcinoma.

I also chased up why the PET scan is taking so long. The Medical Aid has not given approval yet. Last time it took days. Now so far it has been 2 weeks.

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June 13
I just got news from my Medical Aid. The PET scan is approved.
About 10 minutes later I got a call from, and had a good chat with, the PET scan Ladies. It looks like the morning of June 22 for my PET scan.
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I got a bit of a shock today, while reading an article in a US Army magazine.
They took active duty Soldiers that had lost either :
1 leg below the knee. (BK).
1 leg above the knee (AK).
2 legs below the knee (BBK)
or
2 legs above the knee (BAK)
They also took about 100 un-amputated soldiers.
All of these people were required to walk (no running or jogging) fast in a straight line for 6 minutes.
The military calls this a 6MWT (Six Minute Walking Test).
The total distances walked were measured.
The distance each group averaged for 6 minutes was:

Able body: 761 m
BK:           661 m
BBK:         576 m
AK:           542 m
BAK:         482 m

 I am an AK, and last week I was just able to walk 2400 m in 66 minutes. That means a double above the knee amputee can walk over twice as fast as I can. ??? What is my problem?
Of course these are young, fit, soldiers, that have received the very best treatment, training, and rehabilitation possible, and they have the best prosthetics money can buy.
The US Military plans on spending $1.76 million for each above knee amputee.
The best prosthetic knee I own, was bought on eBay.

The Army has done some major work on lower leg prosthetics for soldiers returning to active duty.
These papers are all available for download. It is like sipping water from a fire hose.

AK combat soldiers prefer pure mechanical knees while on combat patrols, but use microprocessor controlled knees once back inside the camps.
In the 6MWT the type of prosthetic knee was statistically irrelevant. Not so with the prosthetic feet used. Most military AK personnel are issued feet like these:
"carbon fiber J-shaped energy storage and return feet with shock absorbers and torque rotators"
Us civilians have to pay house like prices for these things.

Interestingly it seems as if personal preference is the single largest determining factor in the usefulness of a prosthetic foot. Users perceive differences between different foot designs with no evidence to support the differences. One foot just "feels" better than another.

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June 14
I decided to see just how far I could walk in 6 minutes.
This required changing the setup and adjustments for the prosthetic leg.

The knee locks stiff with weight on the heel, and breaks loose as weight shifts to the toe. There are three things that control when the knee breaks loose on a Total Knee 2000 or 2100..
The over center geometry of the leg.
Geometric lock settings.
The angle of the foot in relation to the leg.
The easier the knee breaks, the less energy it takes to walk, but it is far less stable when washing dishes or walking around in the house. Falls are much more likely.

For my walks around the Park Run courses, I had lowered the toe on the foot. This makes it easier to go downhills, but harder to walk up slopes. This lowered toe resulted in less stability.
The area for my 6 minute walk is flat and tared. So I wanted the foot back to level, but also wanted an easier breaking knee. So I adjusted the foot angle and the over center angle on the Total Knee 2000.

Once I was happy that I could go fast, AND not fall, I went to the section of road by my house and walked fast for 6 minutes. Using 2 different GPSs, I went 401 and 403 meters. Far short of even the double amputees tested. :-(
I went home, had lunch, and increased the knee flexion resistance, and decreased the extension resistance. This should make the leg swing forward quicker, and therefore allow more steps in the same amount of time.
Back on the road, and away I zoomed for 6 minutes. 400 meters, and 401 meters on the GPS. The same speed, no change.
I went home and installed the Total Knee 2100 from eBay. It is a much better knee, but also not a 100% knee. It leaks oil, and makes squishy noises. I got it all adjusted as best as I could, and then back to the road.
This time I did 420 and 422 meters in 6 minutes. That is a 5% increase. I didn't feel faster or better, but obviously it was.

I think I agree with the Army's result. Basically....
A good knee is essential for stability and mobility, but the type and cost of the knee is not a significant factor in speed.
A variable angle foot, a shock absorber, and an energy recovery system is more important in gaining speed.
If my goal is a one hour Park Run, then I think a variable angle foot to handle slopes better would benefit me far more than a fancy bionic knee.

Also losing some weight, and getting in better shape wouldn't hurt either. :-)

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