A knee replacement is in the near future for me and I have been having and ongoing discussion with my ortho doc(s) about the level of cycling I can do post replacement. I cycle about 150-200 a week now and usually do a couple climbing rides a week. The short version of the discussions with my doc(s) is that they suggest I will need to curtail my cycling post replacement in order to limit wear on the joint and possible premature failure.
There are folks here and on other forums with knee replacements who cycle high miles at good speed and also climb a reasonable amount. This seems at odds with what the doc(s) are telling me. When I look at the TKR medical literature it seems there is not a large body of evidence about the medium to long term effects of athletic activity on knee protheses. There is some, but nothing that would be definitive either pro or con for higher levels of activity post replacement. And, yes, generally the literature suggests cycling post replacement is "good for the knees" but my reading of this is that by "cycling" the literature generally means "riding a bike" and not "cycling" as forum members would understand the term.
So, I have an appointment soon with one of my ortho docs and I wan to discuss some of the literature I have found and forces on the knee from various kinds of physical activity, but especially cycling so I can understand their conservative approach about higher mileage cycling post replacement. I have found only a few articles about this and wonder if anyone here knows about the comparisons of forces on the knee from various types of physical activity. The one item I found seems encouraging:
"We estimated the patellofemoral joint forces generated during pedaling on a bicycle ergometer. Our calculations were based on measurements from a force transducer mounted on the pedal, 16-mm cine-film sequences, and biomechanical models of the cycling motion and of the patellofemoral joint. Six healthy male subjects cycled at different work loads, pedaling rates, saddle heights, and pedal foot positions. The maximum patellofemoral compressive force was 905 N (1.3 times body weight [BW]) when cycling with an anterior foot position at 120 W, 60 rpm, and middle saddle height. The mean peak compressive force between the quadriceps tendon and the intercondylar groove was 295 N (0.4 BW), and the patellar-tendon and quadriceps-tendon strain forces were 661 N (0.9 BW) and 938 N (1.3 BW), respectively. The patellofemoral joint forces were increased with increased work load or decreased saddle height. Different pedaling rates or foot positions did not significantly change these forces."
The other items I have found also suggest that relative to other activities, cycling does not generate significant forces on the knees, but these are generally studies that are using more of a "ride a bike" definition of cycling and not more intensive road biking. Anyone have some information that might help me in my discussions?