Prosthetic ROM Limit

[edk]

Sorry if this is the other end of the ROM discussion but the question is
what does it feel like when you reach the engineering limit for ROM of
your prosthesis? Though it varies by model I've heard that most of them
are designed to give a max bend of about 120 degrees. So I'm 5 months
out and dutifully doing exercises/stretches without a PT person so I have
no ROM measurements other than my eyeball and I'm probably close to 120.
Well lately when I do quad stretches I've gotten to the point where
I can't get a good stretch on my quad. Rather than feeling it in the quad
I feel it in outer lower part of the knee and it radiates down my shin. Is this
what it feels like when the hinge hits the doorstop?

 

[VikingFan]

I have a Smith and Nephew, about 9 weeks out from surgery and have a ROM of about 126. My PT doesn't seem to think there is a limit and I should be able to match my healthy leg ROM of 131. Most of the pain I feel when stretching is that 'bunging up' feeling right behind the knee.

 

[JenniferG]

So I'm 5 months
out and dutifully doing exercises/stretches without a PT person

You're my hero!

Only limits i've heard of or experienced is my vigilence at stretching things and the back of my thigh. I'm thinking I want to work more on better squatting. my mobility for "down low" is still limited and that is due to my negligence of working at it. No resistance bending knees in a sitting position though.

 

[edk]

Actually the funny thing is that I've never been very flexible
but since I'm doing stretches with both legs. My non-surgical
leg has gotten to the point that I can almost kick myself in the
butt with my heal - something I've never been able to do in
my whole life.

 

[Doug]

Jenn, make sure and have a stopping point when you try and do the squatting.. Place a stool or chair at the height you want to get to...That way, if your thighs give out you don't fall....Also, it is best for your balance if you can elevate your heels some what.

 

[schoust]

Funny I was just chatting with my therapist about this exact subject and I am in complete agreement with Viking Fan the only limits on the device are the person it's in. I think they are designed with 100% flexion in mind. At least my Smith and Nephew knee is.....Ralph

 

[DaveW]

The Nephew&Smith Jounrey has a limit of atleast 130 degrees.

Dave

 

[schoust]

Hi Dave not sure exactly what that means? So are you saying there is are there isn't complete flex with this device? I mean the OS told me he had the leg completly bent?

 

[JenniferG]

Doug, have you been watching my poor and dangerous form. The times, I tried have had no stop point, just when going for something I try and pus a little further than is comfortable. Safe is better.
And on that note... Then 130 it is as I have 2 smith & depuy journeys. Must have been a good marketing and DR incentive program as they seem very popular lately. ha ha ha lol.

 

[beachcomber]

"completely bent" doesn't necessarily mean more than 130 degrees. Your natural knees have a limit too. The new implants are improving in design to be more like real knees and are getting better all the time.

Hi Dave not sure exactly what that means? So are you saying there is are there isn't complete flex with this device? I mean the OS told me he had the leg completly bent?

 

[Josephine]

Hi Dave not sure exactly what that means? So are you saying there is are there isn't complete flex with this device? I mean the OS told me he had the leg completly bent?

Not sure where you got the doorstop analogy from. Modern knees are not hinges, they are a free ranging pair of prostheses which glide upon one another but under the constraints of the collateral ligaments, the quads (patellar) tendon, the hamstrings and to a lesser extent, the capsule.

Therefore, the only limit to the flexion is the bulk of this soft tissue and its willingness to let your knee bend.

 

[beachcomber]

Jo---

"doorstop analogy?" I don't understand. Did I miss something? Or is it just a "blonde" day? lol

 

[ttlncsc]

Hello All,

I read a great deal about knees and talked to some of my fellow med surg reps. I then talked to my OS and talked about knees billed as extended flexion. He mentioned some concerns that he had due to mechanical failures that his partners have experienced with the extended flexion model of a popular knee. He said the regular model would give me as much flexion as I measured preop---125 on my own and 135 when he assisted. Yesterday, I was released from PT and I hit 126 on my own and almost 133 with a little push. Don't know what the limits on ROM happen to be but active folks on the forum seem to generally reach a return to their activity levels. I'm 9 weeks post op and am going to shoot for a little more flexibility unless warned. Josephine weighed in on this subject and it appears we can get what we can get. Hope you all have a great day and a restful night. Regards, Tom

 

[Josephine]

Is this what it feels like when the hinge hits the doorstop?

In post #1, Beach!

 

[Josephine]

I'm 9 weeks post op and am going to shoot for a little more flexibility unless warned. I'd be interested to hear Josephine weigh in on this subject.

You go for whatever you can get. It's not going to harm the prostheses in any way whatsoever. See my images. Your limits are mostly dictated by the soft tissues, not the prostheses.

 

[beachcomber]

well..... that explains it....thanks Jo!

My new knee ROM is as good as or maybe better than my other knee. I am doing deep squats in my hot tub these days (groan) and feel the "pull" less in the new knee. I haven't had my ROM measured in months but rely more on function. Doing great and getting stronger all the time--- whatever the degrees of flexion might be!

 

[1jt@atime]

I have a question about ROM that I've not seen addressed. My first kr is almost 11 months old and when I bend the knee back as far as it will go, I still get that same achy feeling that we all know when trying to achieve better ROM. Will that achy feeling always be there or does it slowly go away? I dont remember that pain before knee replacement. Karen

 

[Josephine]

Can be yes, can be no. There's no way to say, I'm afraid. God willing it will be no!

 

[edk]

I knew there is no hinge it was just an analogy about a stopping point. I think I found
out where I got the number. I saw a study where "success" was measured as having
0 extension and 120 flexion. While I was poking around I found exerpts from a book
on knee arthroplasty which said what was mentioned before that some of the
extended flexion knees are a little more fragile. It generally said in very medical language
that the limits in most cases wasn't the hardware it was the disease process and how much the surgeon cared to or could clean up the knee when doing the installation.

 

[ship4]

I have been reading this string with interest. I have my own take or theory on this ROM business. I do believe the ROM you will get from any TKR is dependent upon the amount of ROM you had prior to your surgery.
For myself, pre-op my ROM in both knees was 135 and 0 which is considered normal ROM. If the muscle memory already exists within the knee for the ROM, it will come much easier to what you had prior to the TKR. For those who have suffered for years with limited use of the knee and atrophied leg muscles, it is going to take a long time to build up the muscle fibers especially those in the quadracept muscle which is cut during the TKR surgery.
It will take lots of work, and pushing your muscles (it will hurt!) to gain muscle fiber strength after not being used for years. It will ache. Muscle fibers produce Lactic acid which makes them ache when they are used to capacity. Muscles make lactic acid deliberately, producing it from glucose, and they burn it to obtain energy. The lactic acid is taken up and used as a fuel by mitochondria, the energy factories in muscle cells. The reason trained athletes can perform so hard and so long is because their intense training causes their muscles to adapt so they more readily and efficiently absorb lactic acid. Athletic performance improved when athletes worked on endurance, running longer and longer distances. Consequently if we continue to work on our PT for our knees we will make our muscles stronger and able to absorb more lactic acid.
So, if your ROM was limited prior to surgery it is going to take lots of hard work to stengthen the muscles that were dormant or unused for so very long. A longer PT recovery than those who enjoyed a normal ROM prior to surgery.
In my case, my ROM prior to BTKR was normal in both knees. I believe I should be able to work hard to get my Johnson & Johnson Depuy Complete Knee Systems to move at the normal ROM of 135 which I had prior to surgery.
Just my opinion.
Best,
Crystal