@VW54, good to see you here! It sounds as though you've been very busy on the domestic front and perhaps that's keeping you from building some regular walking into your routine? If so, just try to figure out how to build a daily 20-30 minute *date* with yourself to get your knee in better shape for your big trip. If walking one km is too far, then cut it back to a comfortable amount and build gradually from there. I find just a few minutes daily on the bike really pays off in the stretching department and that helps me walk further and more comfortably; win/win.

That said, I'm not walking huge distances yet, and in fact don't measure miles, just time. I'd say I'm good for about an hour, maybe 90 minutes under unusual circumstances (read: slow) lol. If I go more than an hour, I definitely need ice afterwards. If not, I generally don't, so it's still a fine game of balance.
I know you are concerned about the sound effects, but it is a common phenomenon here and hey, it doesn't hurt, right? My knee is more of a *clicker* than a *clonker,* though it does clonk at least once a day. It's just a nuisance sort of thing, but it sure beats the grinding pain of OA, right? I really like your sound solution when heading for the Underground; good thinking!
I hope your visit with the OS goes well and can't see why it shouldn't? I'm sure he's not expecting you to be an Olympic Athlete, right? Remind him you still have at least 7 more months of healing to go! And yes, I know, none of us want to hear that, but it's true; pffft! Also, be sure to inquire about your ankle swelling and the spasms you're getting. Let us know what he has to say, ok? Only recently, I realized I haven't been stretching enough, especially before bed, so I've put that back into my nightly routine. I see a positive difference in overall comfort when I remember to do it, especially in the hamstrings.
I'm not familiar with that drug or supplement you mentioned unless it's Glucosamine with a different brand name? If so, I took it for about a year pre-bionic hip, with no results, so I stopped. It was also pricey for something that didn't seem to provide a positive impact. Just my take, of course. I know others who swear by it.
It's great that real life has taken over for you, but don't forget to keep us posted and update us on your trip as well! Hang in there and take care of that knee and yourself as you prepare for this big, exciting trip; woot!
