Two big things. First, I had my MRI today and am officially diagnosed with chondromalacia patella, aka patello femoral syndrome. This is inflammation on the cartilage of my kneecap caused during the crash when my kneecap was slammed into my leg and pushed way towards the inside during the impact. The good news is that the menisci and major ligaments look fine, so no obvious reason from the MRI for surgery at this point, though I may still get "scoped and scraped" if the pain doesn't resolve after today's giant needle cortisone shot and PT.
I am happy to have a plan. Hope I get back on a bike soon, even if it's just a trainer.
Updated: this is totally "hindsight is golden", but reflecting back, I wish I had more vigorously pushed back on the PFS diagnosis, given my prior history of no knee problems and the acute pain I was experiencing. Surgery much later on revealed a structural cause for all of the pain and swelling (torn meniscus), and had I had a decent MRI at the outset or a more insightful ortho/PT at the beginning, I might have spared myself a lot of pain and recovery time. (Got Bitter? Actually, I am kind of over it at this point).