It's not just surgical intervention but post-traumatic osteoarthritis (PTOA) from joint trauma that's a big red flag. And it starts with some type of injury to a joint - usually a torn or partially torn ligament, tendon, cartilage or even a fracture that initiates a degenerative process. A signficantly torn meniscus is a big one that invariably leads to OA whether it's surgically repaired or not. And OA of knee, ankle & hip are the bad ones for runners and those doing other high-impact activities (13 million adults age 60 & older have clinically diagnosed OA of just the knee!).
I think it is relative to the type of injuries folks have had. Soft tissue, mild tendon, and anything folks can get over with a few months off or even 6 months with intervention tend to be indefinitely sustainable. So how hard one trains is not the primary focus.
But based on what I have gleaned from two orthopedic docs I know, one a surgeon; any injury that requires surgical intervention is a red flag for longevity as that area becomes a permanent potential point of problems for the future. I personally know excellent runners younger than myself who have had various screws, plates, and transplants of other parts of their bodies put in their feet and knees. I’ve seen them fall by the wayside over the years.
I know folks just LOVE to point to people who’ve had both knees replaced and keep on running. This is the kind of inductive reasoning that people use to justify smoking cigarettes because, after all, Jeanne Calment smoked and she lived to age 122 and 164 days. Extreme statistical outliers are, after all, extreme by definition.
I have ankle, knee & hip OA. Several years ago during a sprint finish of a 5k race, I completely ruptured the Posterior Tibial Tendon of my ankle - it literally exploded as I engaged in a full uphill sprint finish dropping me like a lead balloon! 😖 (this was bad and I've had some pretty hard hits from my football days). Surgery was an option but not recommended primarily because of my age (lengthy non-weight bearing recovery) and the fact that with the right rehab I could return to some form of running. Rehab was about 3 months before a return to full running but with a lot of limitations (mileage, intensity, racing, etc.).
But repetitive use of a traumatized joint leads to PTOA. In my case later follow-up radiographs & MRI showed significant degenerative changes within the cartilage between the tibia & talus. Any cartilage degeneration of a joint is bad news for a runner. My foot & ankle surgeon says in the future I'll be needing a complete fusion surgery which is a major procedure with plates, screws and all that fancy hardware. Right now I'm told to let pain be my guide, continue rehab excercises & more non-weightbearing activity.
My knee PTOA (mild) is from a partially torn ACL from my college football days. And I have no idea where my hip OA (also mild) originated from. But it's only one hip with moderate soreness from time & time...nothing compared to the ankle.
Running on replaced joints is probably is not advisable and is just going to wear the parts out more quickly. However, that being said, I know two guys from the master running club I used belong to that continued to run after knee replacements. One, a faster running in his age group, had a torn meniscus about 12 yrs ago that was surgical repaired and he continued on with a pretty heavy training & race schedule. In his 70s, he developed severe PTOA and had a full joint replacement and still runs & races, but much slower now with a pronounced shuffle-step type form. The other guy, in his late 60s, had two partial knee replacements and runs very slowly with the same shuffle step motion. It's almost fast walking with a gliding motion as they're trying to minimize impact forces.
I'd say soft tissue injuries, mild tendon, ligament & muscle strains, and tendinitis type stuff is nothing compared to severe trauma to a joint. Those aforementioned pathologies are manageable with the right rehab & nutrition, IMO. Trauma to the structures of any joint is bad news and will invariably lead to PTOA, and pretty much game over for high-impact activities. So, count your blessings if you haven't had any major trauma to a joint.