Is a C-leg prosthetic knee for a prosthesis all that great?

People with two good legs - and even Below Knee amputees cannot understand . . . without a knee you can control with muscles, you are at the mercy of your eyes, your balance and the level or smoothness of the terrain.


All amputees are not amputated equal, and you are not a REAL amputee unless you are an Above Knee amputee. Hip dis-articulated amputees suffer an even worse hazard. Even the State of California does not consider you "disabled" for the purposes of a Hunting or Fishing license UNLESS you are amputated ABOVE the knee.


Does it really make all that much difference? YES - it does. People who are amputees of other sorts - and even upper extremity amputees - like arms or hands, cannot even begin to imagine the fear involved in walking on and depending on a mechanical prosthesis knee which is as unpredictable and moody as shifting your weight upon it or having to try to stop mid-step because some genius cut you off. Most prosthesis knees will UNLOCK or never do lock, and you will uncontrollably fall. Some knees have no lock feature at all - and you will fall.


One such hydraulic knee is the Otto Bock 3R80. It depends completely on the proper setup of the prosthetic for safe operation and even then the wearer must look at where they are going and constantly think about each step. It is a bit un-nerving - even for a 9 year veteran amputee. I have walked on a 3R80 - and it is a smooth comfortable walk - however if not setup right - it will go out from under you faster than you can blink. So let's talk about walking in the dark.


Nope . . . let' forget about it. If you cannot see where your next step is - forget about it - it is a safe bet you will fall. Something has to think for you that you are falling or the step is not going well and complete - because guess what . . . you have no knee to transfer sensation to that you will need to catch yourself from a stumble.


Today - all the Microprocessor controlled knees have some form of "stumble recovery mode" which tries to do this, and there is NO kind of non-microprocessor controlled prosthetic knee which can do this. Or slopes safely, or stairs acceptably. So . . . now let's cry fowl, because the only study which drives home this point I could find was from Otto Bock for the C-leg comparing it against other Otto Bock non-microprocessor controlled units - one being the 3R80, the other being a Mauch type unit knee leg combo.


Surprise, surprise, when a bag is put over the amputees' head, he suspended in a safely hanging harness and asked to walk - when the unlock trip is triggered by the researcher, they fell almost all the time - but with the C-leg. Anytime a person with two good legs tries to tell me something about being an amputee, I ask, "should I tell a woman what it is like to be a woman just because I read about it?"


Then they have stupid look on their face. The last time I heard a co-owner of a prosthetic business - who is female, the wife of one of the owners, and faced with a billing issue they knew was impossible, try to tell me, I do not need a fancy microprocessor controlled leg - because mine needed repair and the insurance was gong to be a rough go to get it paid for even though the doctor prescribed the repair part - I wanted to go off on her and say look b____h you do not get this because you have two good legs. Instead a bit my tongue and outlined the multitude of features I needed in a leg to try to get back into the profession I was doing and that only halfway shut her up.


So before you rush onto eBay to get a C-Leg and think you are going to just bolt it on away you go - . . . For those of you who do not know - YOU CANNOT get the software to program a C-leg yourself, nor the DATA CABLE; and if the pylon is unplugged for any reason - you will LOOSE the present programing, the unit will go into "native mode" and lock up stiff until you get it re-programmed. An Otto Bock prostheticist is not allowed to program the leg unless it meets Otto Bocks' operational and service standards, and that means current upgrades and parts comprising the entire prosthesis must be present on the leg- and they must check if you bought it used, or it is stolen or bought off eBay.  Otto Bock will have a record of who originally bought that C-Leg prosthetic knee.


Then they will want to send it in for service - and now comes the bill . . . Here's what one of their top repair facilities in Germany had to say on this subject: ""I have worked with otto bock quite a bit in the past and have been to their main shop in Duderstadt, Germany... First these are my personal opinions; Otto bock is/are perfectionists to the highest level, before a new product hits the end user they go through the most rigorous testing I personally have ever seen.. Ossür in my opinion is the exact oposite...(i am reffering to the "power knee" its just not ripe yet..)they do also have good products though... ok back to topic; before a prostheticist is aloud to sell/provide a c-leg he has to go get specialy "c-leg" certified etc and a whole load of stuff. The software that is for the c-leg is some of the most "safe-guarded" I have ever seen. When you bring your leg to checkup they can tell exactly who tinkered with it, every piece of software has its own serial number and is meant for one shop only--you sign (as a CP) contracts saying your in deep s*** if you share their software...(yes their software phones home, ask wireshark) scenario; you buy a "used" c-leg bring it to a non-c-leg-certified CP, not possible, only a CP that is c-leg-cert. has the proper software to change it, (that is legally speaking..) These are just some of bock's arguments, I think its just...making money. They insist that its quality managment...For the most part I do not agree with them. I dont know how much you intend on paying for the knee, I am sorry to say this; I would not buy it if it were over 3K and over a year and a half old... it would be horrible to pay a bunch and have it not setup properly or it break.. 9/10 c-legs that I have seen have had to be " seriously waited" on at some point.. on the other hand, I can imagine it would be wonderfull if you had one, I'm sorry, It all works down to Otto Bock making money..chris"" December 8, 2009 (type and spelling errors reproduced in full)


While a C-leg is a hydraulic SNS type knee, it is also NOT self learning while the Rheo Knee by Ossur and Smart Adaptive from Endolite - are.   So I say cry foul . . . because there is no Apple for Apples comparison to OTHER microprocessor controlled legs to see whose stumble recovery mode worked the best - only this comparison to other Otto Bock knees by Otto Bock themselves which have NO stumble recovery mode features at all.


IF . . .  you know how to - and can hop fast enough so the hydraulics go back into stance mode - then - and even a standard hydraulic mechanical knee, will offer some support if you put it down and weight on it - but the incident will happen so fast, likely no human will be able to get their weight an posture in a position to take advantage of that hydraulic support anyway - and they will uncontrollably fall.


I walk on a  C-Leg right now, and I will say it is the only knee out there that does perform as advertised, and it does have stance support that is always on unless you shift weight and push on the toe wrong which will COMPLETELY unlock the stance for the prosthetic knee to expect the  walking phase.  STILL the only other two knees I have walked on that were as safe or safer was the Ossur Century 2000 or the Otto Bock 3R60.  Both of those knees are fairly harder to fall in - as the Century 2000 (and 2100) actually mechanically locks when standing and the 3R60 has a stance flexion feature which is also a lock when standing


So it is not so much a question of is the "C-Leg" all that great - the question is whose Microprocessor controlled knee is the best and why. You can find more info on the article here =>


See also