brudford

I know there is a thread over at the Over 50 section about TKR but it has gotten to long and changed focus as long threads tend to do . I had a TKR, right knee about 6 months ago and I'am a road rider. I am at 15 miles each ride now . Does anyone know of any long term studies that show what the mechanical wear is on a knee replacement ? I have asked several Orthorpedic Surgeons, PA's and Nurse Practicianers and PT Therapists who work in that disipline and they just either shrugg their shoulders or do not know . Surgeon told me to expect at least 20 years of life for my new knee. He cannot answer if that 20 years would be diminished for an avid cyclist ? Thanks

Flip Flop Rider

I'm saying no way that riding would diminish the time the knee would last, with it being a non impact activity

would think that cycling would strengthen the muscles surrounding the knee, increasing the longevity of the replaced knee

the replaced knee is titanium, so how long does that last? forever? the surrounding tissue is the issue and again, biking would strengthen those areas

that being said, I am a high school psychology teacher, so there's that

brudford

Thanks for the reply . I failed to mentioned that I have been an RN for the last 26 years and have access to Health Care Professionals daily and still could not get my answer, or the answer I want to hear . Yes, Sureons are very big on non-impact activities such as cycling and swimming . Strictly no running orders although . My concern is surface to surface frictional wear . Yes ,high tech metals and polymers are used, but any material will wear over time and extra usage . This surgery was so painful and the rehab is so long I never want to go through it again ! Thanks

metalheart44

I asked the same question prior to my knee replacements and received no answers either. I did a casual literature search and also found little that was helpful. There have been a few cadaver studies of athletes who pushed the envelope on using their knees after a TKR, but my memory of the findings is weak. Many of the studies of athletic activity post TKR I found often mention biking or cycling, but close examination of what the activity level, as I recall anyway, is that it is very casual cycling as opposed to serious road riding. It has been a couple years since I did those searches, but a quick look at Google scholar should help you to find anything recent.

I came away from the lit search and discussions with several surgeons with the impression that those of us with knee replacements who are road cycling at more than a recreational level are in a unique group as far as knowledge about the effects of wear on the implant, specifically the "wear resistant" plastic spacer. And, with younger cyclists/athletes (40+) getting knee replacements the wear question has more unknowns about the longevity of the spacer.

On a recent visit to an Ortho doc to address some tendonitis issues in my second knee replacement I once again asked about the wear and tear issues of the cycling I do --- 5-6k/year depending --- and specifically climbing and faster flat rides. His comment was something like, "Most 73 year olds with knee replacements are worried about if they can walk to the bathroom after their surgery and not if they can climb a 14% grade. We just don't know enough about this yet."

After my one year follow up appointment with the surgeon, he said "See you again in two years," which is apparently the standard protocol. Since I have questions and concerns about the effect of my road cycling on the implants, I asked for another follow-up in a year and he agreed.

I can probably dig up a few of the links I bookmarked a couple years ago about athletic activity post-TKR, but I am hoping there is some more recent given the wider age range of people having knee replacement surgery. In the mean time, ride on.......

cyclintom

As an RN yourself you should know how many different manufacturers of replacement knee joints there are. And each one is differently configured of different materials. So unless you went straight to the manufacturer with a question like that you'd be unlikely to get an answer with any confidence level.

Troul 

My aunt that had a tkr was told 5 years if body weight was not brought down within 20% of "average" lbs for her weight height age.
She's exceeding 10 years & has lost some lbs, but is still over the 20% as predetermined as a need for change.

metalheart44

I would encourage you to talk with your surgeon about your level of activity and related effects on the prothesis. There are lots of potential causes of TKR(A) failure, but osteolysis related to wear on the plastic / polyethylene spacer is prominent in the literature I looked at a couple years ago. And, just a quick search for studies about the wear on the spacers related to activity post TKR does not indicate to me that much is known by either manufacturers or clinicians. For example, here is a quote from this study about osteolysis related to spacer wear:

Some other factors that have shown to increase polyethylene wear and/or mechanical stresses at the implant/bone interface can be at least partially influenced. For instance, the type, extent and intensity of physical activity could be modified to avoid a premature TKA failure. However, there is a relative paucity of literature data directly relating polyethylene wear to patient activity in TKA, and many recommendations are based on simplified biomechanical models [126] which solely provide information on level walking. Although this is the most frequent dynamic activity of daily living, it does not exclude the possibility that other less frequent activities may be more damaging. More representative wear scars have been obtained during in vitro testing, when other activities of daily living were included and generated wear rates were higher [127].

That particular article is worth a scan, but there are others. I am still convinced that we cyclists with a TKR have a level of activity that was not anticipated when this surgery was developed and the knowledge about how much cycling with what effect on the replacement joint is still developing. To me that just means I need to keep checking for increased inflammation levels in the CBC, ask for yearly X-rays and attention to how my activity level might influence the need for revision surgery.

brudford

Good idea , I will be contacting the Ortho office to see if they can give me the contact number of the appliance ( knee ) manufacturer . I will post any information that I recieve from the manufacturer .