GimpyDavid

I am a 70 y/o male with a history of 5 left
Total Knee Replacements and would like to return to recreational bike riding.
However, I have only 95 degrees of left knee flexion which prevents me from completing a full crank revolution.
I would like some recommendations for acquiring asymmetric crank arms which will accommodate my left knee ROM
limitations. Thank you-GimpyDavid

groth

Not sure about asymmetric, but you could try short cranks or crank shorteners. I suppose if you did that only on the left, it would be asymmetric! In any case, crank shorteners are what I used before my total (right) knee replacement (and I only had 1, how did you ever do 5???).

Good luck,
Ed

OldTryGuy

5 ???? What happened, wearing out of joint, failure, improper installation, build up of scar tissue causing problems**********

I am years over-due for a right replacement that also requires an upper tibial osteotomy, actually left needs it also but not quite yet so curious as to what caused so many replacements.

Thank you.

+1 on the crank shortener

JoeKahno

Throwing a shorter crank arm on the left side shouldn't be a problem. The only possible issue I can see is that if you adjust the seat height to get minimum flex on the left, your other foot may want to lift off the pedal at the bottom of the stroke. It's worth a try. Worst case you may have to go to a matched set of shorter arms This will reduce your leverage slightly but shouldn't be anything you can't compensate for with the available gear ranges.

Doug64

This is a bike I gave to a freind. We shortened the left hand crank by drilling new holes in the appropiate places to accommodate his left knee's limited range of motion. A local machinest driiled the holes, and our lbs tapped the 9/16" left hand threads for us. It worked well, but he did not do long rides with it.

Flip Flop Rider

how much does 5 knee replacements cost out of pocket if you don't mind me asking?
thanks

Doug64

I found a better picture than the one above.

banjaboy

I have had both knees totally replaced this past couple of years. My heart goes out to you my friend!!!!!!! 5 times? My question would be why and why would a surgeon keep doing that. I found my road to recovery wasd the brutally painful re hab physio. I did what I was told, through tears many times but I must say Im 100% now, 1250130 both sides, getting back into biking again after being unable to do it for years. Have you thought of a personal trainer that specializes in TKR? That might help, just a thought.

Stormy Archer

A kind of big problem with this that no one seems to have mentioned is that if you have one crank arm shorter than the other, you will need to set your seat height according to only 1 crank length. If you set it to the shorter crank arm (which is presumably what you'd need to do) then your seat will be higher and the other leg will be over extended at full crank rotation. If you set your seat height to the longer crank arm, then your seat will be lower and the short crank arm will be less helpful since you are closer to it. knee will be bending more, and will not reach full extension at the bottom of the crank rotation.

I'm pretty skeptical this will help much. It may enable you to get around on the bike but keep in mind generally the longer cranks are 175mm and smaller cranks are 150mm which is only 2.5cm, not a huge change. And if you go small enough you're going to be straining going up hills which is also presumably bad for your knee. BUT plenty of people bike with 1 leg especially clipped in. So if your other leg is in good shape and you get that fitted and set up well it could work.

banjaboy

A shot in the dark here....Im thinking if you had a top class Ebike with a modified crank arm on the problem side might got you out there and in time would increase your ROM and you could phase yourself into a progressively longer crank until you get that full rotation. Failing that.......maybe a top notch bike fitter/.kinetics dude might just be able to help. I feel guilty that both my replacements turned out to be perfect. But man, I know what knee issues can do to your life.