I am going to stray a little from topics of my other posts, to post this rather long rant of thoughts about my road-testing of 3 different computer-controlled knees. There is a lack of user opinions around this subject, and I’d like to post my opinions and observations, in case they could be helpful to somebody. Originally, I wrote this for the O And P list as it originally gave me a lot of hints and clues, before my tests started. I cleaned it up a little, and corrected (most of) the spelling / typo mistakes, but the basic content is the same as found on the list. So if you read it there, no need to read it again.
Here is my original post to the list.
MPK = Micro Processor Knee, A prosthetic knee joint fitted with a processor to help continuously gauge and adjust the behavior of the knee during gait.
Middle of November last year I wrote about opinions and benefits/weaknesses about MPK fitted legs for people in my situation. That is left femur and right Crux amputees. I have now had the pleasure of trying out all three mentioned MPK's and the comments and tips I received from the list was very helpful in that process. So thank you everyone on the list who responded. I have now received a healthcare approval and have decided and acquired one of the three.
First of all - I think that we are still very early in the evolution of MPK's. Many features seem engineer driven and not necessarily something I as a user would benefit from There is also too much "following your competitors" and too much evolution in there. A little more “true invention” and breakthrough would be nice. But still – when coming from an old pneumatic leg that only allows me walking a a predetermined pace, going with any of the MPK's was a step forward. (pun intended). That was clear after walking the first few steps on any of the three knees ...
**** DISCLAIMER ... The following is my impressions as a user, based on my limited testing, and does not necessarily reflect the opinions of practitioners and other professionals I have met in this process. ****
(read - I'm not trying to step on anyone's toes .. just trying to give my immediate feedback).
1. The Plié 2.0
I only had the opportunity to try this out for one day, but despite the setup being down to - "bolt it on and start walking" it was by far the smoothest leg "out of the box" and the easiest to start walking on. I haven't been running since I tried to stop a train 24 years ago, but after putting this leg on, I was taking my first running steps, less than 30 minutes later ... That kind of sold me on the idea of MPK’s .... I also liked the idea of an interchangeable battery.
But I seriously doubt the water resistance that this leg claims. And there was wires hanging visibly and semi-loose on the inside….
I works as a freelance IT consultant, helping customers choose between a number of different products and there was just something about this product that didn't seem "solid" to me. And when looking at the time frame for a healthcare approval I had to think long term. If it was the third generation and not the second, I might reconsider. Also - I don't know how easy it would be to service this leg if it failed while I am travelling somewhere outside US or Europe?
2. The C-leg.
It took me about 2 weeks to learn how to use the c-leg, and from then on I loved it! It was predictable, yet did supported me in what I needed to do. But I also had to learn how to use it. There wasn't the same initial "this is nice and fits me well" feeling as with the Plié 2.0. But "predictable" is a good thing I guess. Giving the trial knee back after 3 weeks and returning to my old knee was a sad experience. There is a learning curve, and having a good practitioner that was able to explain to me how to use it, and how to gain trust in it was VERY helpful.
To sum it up. After set up to suit me, it just works the same predictable way every time you take a step in the same way. I'd definitely want that if I was a new amputee. Downside is that it locks when running out of battery. First thing I did was to run the battery dry to see how that worked. It didn't. Try walking with a leg in a cast, without crutches ... it's impossible!! Imagine going on long flights where you might not be anywhere near an outlet for a while. Not cool. And imagine sitting in an airline seat on couch, and having a locked leg?? Not possible.
Another thing is the quirky "second mode". My cardio consist of me working out on a stationary bike, and having to jump on my toes all the time in my gym ... jeeez ... That is something only a sick and twisted engineer could come up with (at one time I studied engineering myself…). And the other option is a remote for doing that? I'm lugging enough stuff around already. So another remote ... no thanks. Why not something more subtle like pushing/tapping a button on the back of the knee at a preset customized interval. Or something else? Spend a few days brainstorming and coming up with something more clever should produce results stunning results ...
Another downside is that you are locked into the Otto Boch components for your leg... feet etc.
3. The Rheo 2
I only had the opportunity to hold and play with the Rheo 2 a few minutes at a sales presentation, and read about it for a few months. I liked the features in theory but didn't know how they would work out in practice. But eventually I got a trial set up, and I had the possibility to walk on it for 3 weeks. I ended up cancelling my return appointment to borrow it for a short trip to Madrid - and thanks for that!! I wouldn't have seen much of the city on my old knee Saved me on room service bills too :-)
Features i like: When I am not putting pressure on it, it swings relatively free. Saves me from the c-leg "second mode". And it works fine in free mode.
One thing I didn't know until the trial is that the more pressure/weight on it, the more resistance in the knee. So you have to trust it and put all weight on it to lock it. In practice this works REALLY well. But i could imagine newly amputees having a problem trusting their knee like that. For example … The first 20 years, I required having my knee lock completely once the heel was touching ground. But then ... maybe that's just me. However, I quickly got around to trusting the Rheo 2, and after that it was VERY natural in the way that it switched between swinging freely and giving resistance.
Another added benefit from this operation, is if you want to get into your car quickly; you don't have to wait for the knee to bend. Just take weight off it, and you can hurl it into your car. Nifty on narrow streets with lots of traffic. “No resistance – swinging freely” is also the mode it enters when running out of battery. With my fairly stable setup I can easily walk on it without battery and I really need that feature. There is bound to be times where I forget to charge, or run out of battery.
Support and maintenance: From what I understand, Ossur is everywhere, so I wouldn't be too concerned about going on long trips with this knee.
It holds battery pretty well ... I sit at a desk or in meetings a lot, and it took me 36+ hours before I managed to drain the battery completely. With higher activity - more walking I'd imagine it draining quicker though. Should I be sitting on long flights, I can turn it off completely which I think is a very nice touch for saving on batteries. And the recharge is fairly quick - 2-4 hours.
There is a bit of "grinding" feeling once in a while due to the way the knee works1 - The liquid and the discs controlling the liquid, working. But it doesn't in any way affect how I walk on it. Also - all the hydraulic knees I have been walking on have lost the oil over time. I like the idea of having something else than old-school hydraulics. Off course that might lead to new and unexpected problems ... but lets see.
Downside is that it is a bit heavier – about a lb. - but in reality I can't feel any difference in respect to the other two knees.
Conclusion
To sum it up .... all three legs could work for me, And all 3 MPK’s are MUCH better than the older manual knees.
Mostly the ability to walk naturally and with less energy at different speeds is a killer feature. Especially being able to walk FASTER, where I earlier had to work much much harder to accomplish that, is a nice touch. I also feel like I am walking more naturally especially after receiving a little training correcting some of the bad habits collected over 20 years. I would add that this training is a must do activity and it gives me the ability to better use the abilities in the MPK’s.
All three knees were giving me these basic benefits, so in reality I think I could be happy with any of them. It was more down to add-on features and my "gut feeling" for choosing technology that was stable and durable enough. I finally ended up going with the Rheo 2, because I liked the features that it gave me, and it’s overall solid look and feel. Mostly the features around swinging free when not applying pressure, and doing the same when running out of battery.
If I was a new amputee though, I probably would have gone with the C-leg, due to the better stumble control and the more "predictable nature" of the c-leg, and I’d then have to deal with a “stiff” leg once in a while …
The post got a little longer than intended, but I hope that my observations can be helpful to some of you. If there is one thing I need to stress, make sure that patients "stick with it" when trying out a new knee. Make sure they walk AT LEAST 2 weeks on it, before judging on it. It takes time to build up enough trust to let the knee "do it's thing" and fully appreciate all the benefits of an MPK.
If you should have any follow-up questions that you think would be helpful, please email me, and I'll get back to you. Or if you have patients with questions, let me know if I can help. I won't recommend one knee over the other - it's all about understanding one's own needs and choosing the right one for you. But I would be glad to share my thoughts on what should be considered, and describe how I perceive the different properties of each knee.
I’d have loved to look at, and test-drive some of the new gear out there such as the coming X2, the coming X3 which I hear is water and dustproof (hello Afghanistan veterans?) or the Endolite Smart Adaptive. (I am a gear-addict at heart). But I think I have found what I need for the next few years.
best regards
Lars
Notes:
1) Info from the O&P list: Christie Ferraro: “The main problem with the Rheo 2's when they came out was a 'grinding' and 'shuttering'. If it keeps happening send it back in they have a software upgrade for them.”
Mine isn’t THAT bad, so I don’t think I have the need for a software upgrade. But thanks Christie. Nice to know!
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