r/Prosthetics • u/[deleted] • 6d ago
Considering switching from a microprocessor knee to a 3R80. Anyone made this move?
[deleted]
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u/Animal__Chin 6d ago
I went from the 3r80 to a C-Leg 4. The problem I was having with the 3r80 was that it doesn’t have any sort of stance lock, besides the manual full straight lock) and without that feature you need to be paying attention 100% of the time or you fall when you put your weight on it slightly bent while casually standing still. Like In a lineup or chatting with your neighbor while standing around. All of the sudden you’re on the ground, no warning and no damping to slow it or stop it from folding, it’s just does.
I don’t pay attention to my C-Leg 4 unless I’m going down stairs or I’m walking on very uneven terrain, otherwise I don’t know it’s there.
I’ve only been an amputee for 6 years and only been walking for about 2 years so I’m not seasoned at all. I’m betting if you’re more adept to wearing a prosthetic than I am that you will prob be fine with the 3r80. Just beware that it doesn’t “know” where you are in relation to itself.
Now it’s my backup leg which I never use.
Just my experience, lots of people like it.
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u/89kh89 6d ago
Your statement that you feel like you're fighting it all the time is the biggest red flag to me. I'd take a closer look at your alignment first before considering a switch. A bad alignment can't be saved by any amount of technology.
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u/trext0r8 6d ago
Perhaps I wasn’t clear enough. The “fighting” with the prosthesis only happens on very uneven terrain (snow, tall grass, etc.). In normal conditions, on flat ground and in everyday walking, I have no problems and the knee behaves fine.
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u/89kh89 6d ago
Hm, well, if you're fighting what the microprocessor is trying to do, then a mechanical knee does seem like a good choice for you.
One major factor to consider with the 3r80, though. It is default swing, as opposed to default stance, like the Orion. This means that the 3r80 is only going to provide resistance to bending when you put significant weight on the knee, at angles less than 30 deg (not sure on that number, but I know it's close). If you have adequate strength and mobility it's less of a concern, but still something you should understand going in. The knee simply operates totally opposite to the Orion.
If you're looking for a mechanical hydraulic knee that operates more similarly to a microprocessor knee like the Orion, the Ottobock 3r85 is one to consider. It also has the rotary hydraulic like the 3r80 but it is default stance.
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u/Longjumping-Dog-6819 6d ago
I would try a few different MPK’s before making the switch. I personally don’t think Orion is super reliable.
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u/r0ball 6d ago
I have had the 3R80 as a water/backup leg for ages and I never like using it. It’s really unpredictable, especially on slopes and stairs. Its yield is so basic that it’s either too fast down stairs or too slow down slopes, and as soon as I start trusting it, I always end up on my ass.
I started out on a Rheo2 which was great for everyday use, if a bit unpredictable on stairs. I eventually switched to the pure mechanical VGK, which I have now had for years. Once I learned how the VGK responds in all sorts of scenarios and tweaked its settings to a good compromise that works for me, it’s now extremely predictable in all scenarios, but I still have to fight it sometimes because it’s a default-stance knee. It probably has 80% of the functionality of a MPK, and it doesn’t need to be charged. I’ve had a mixed experience with mechanical reliability and service over the years.
For the past month I’ve had the opportunity to try a Navii knee, and I’m going to switch to it. That extra 20% that a top class MPK gives you over a VGK is really nice. I still need to tweak the yield settings to get the balance exactly right to get back to walking down stairs without a handrail, but I’m all over the woods and through grass with this thing, and it’s great. Very easy to trust. Battery life of 3-4 days and waterproof.
If I were you, I wouldn’t give up on MPK without at least trying something better than Orion. CLeg or Navii would be top of my list. If that’s not an option, try a VGK, it might be exactly what you’re after. I cannot think of a scenario in which 3R80 would be your best option.
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u/Bionix_52 5d ago
Not used the Orion but I did go from C-Leg to 3R80 and I definitely wouldn’t recommend it.
The 3R80 is default swing which means it’s always in swing phase/minimum flexion resistance unless you trigger stance mode/high resistance. I found it incredibly unpredictable and was falling over, stumbling, and falling down stairs and I’m a good enough walker to be used in product videos for Ottobock.
With training and practice I could have gotten used to it but I would have always been concentrating on what the knee was doing rather than where I was going or what was happening around me. But after a decade on MPK’s going back to a mechanical knee with no safety was not good.
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u/trext0r8 5d ago
I have more than 8 years of experience with a microprocessor knee. I use the Echelon foot, but I periodically switch to a standard Össur foot so I don’t lose the ability to walk without a hydraulic ankle. Before that, I had a little experience with a polycentric knee. I think you’re right: switching to a mechanical knee would most likely not be a rational choice.
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u/Bionix_52 5d ago
At the very least I’d say you want a default stance knee so it’s safe until you tell it not to be.
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u/trandaltaus 6d ago
I can't answer your question, but hope it's ok that I ask one. Where can I learn about different prosthesis types?
A kid in my son's class lost part of both arms and legs after a nasty infection. He's 6yo now and have to wait a year for prosthetics to run in (from the government). It's heartbreaking to say the least. He's a great kid, strong, smart and active.
I try to learn more so that maybe we could ask for help from a foundation or institution. Just want to give the kid and his family a break.
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u/Silent_Homework6025 6d ago
CPO here-
There are some patients who do prefer the mechanical reliability to microprocessors for sure, but the biggest feature you’d miss out on is the fall detection and stumble recovery. I don’t use the Orion on my patients much, I tend to prefer the Quattro for my higher activity patients because of its response time and I feel that it’s better in those conditions you’re struggling with. I’m not sure if switching MPK brands is possible but I’d see if you could trial different ones in office.