I should write more about climbing and displaced patellas, because the conventional wisdom I've been getting from doctors doesn't exactly line up with my experience. Let me just say this, from anecdotal experience of someone who's been climbing for 10 years after having severely displaced his patella, and with a subsequent tendency to repeat the injury:
- Climbing with deliberate, static moves is good exercise for strengthening the musculature around the patella.
- Drop-knee moves are dangerous. My kneecap has popped out doing that.
- Landing after being lowered is dangerous. My kneecap has popped out doing that, too. Didn't even seem like a fast lower.
- Jumping down after bouldering is intuitively risky, but my kneecap has never popped out doing that.