You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
I am having pain in my right knee. I have had my model 3 for three years as well. I am also convinced it is from letting up on the accelerator pedal repeatedly to slow down. I am not doing anything differently in my daily routine to affect my knee.