I'm not sure there's anything you can do to prevent it but I can share some of the symptoms I've consistently seen in my pigs. The first is that they change how they walk, looking stiff and holding their butts higher up than usual. They often end up standing awkwardly, so small portions of the feet look bright red/sore while the rest of the foot looks like it's barely used. That comes along with standing on their back heels with the toes lifted off the ground. You can also feel stiffness in the limbs when stretching them out (while pig is sitting up against your chest). If you're worried about it, it might be worth noting how flexible each of his joints are now so that you have a reference point later on in his life to see how much his mobility might have reduced. Gently stretch/rotate the leg around the hip, knee, and hock -- my boar's hocks are completely fused now so the difference is significant. My boar also squeaks in mild discomfort when he stretches his back legs out, and doesn't lie as comfortably as my two girls -- he won't stretch his legs out while sleeping, for example. And lastly, when the back legs are affected, piggies sometimes do little hops with the back legs instead of walking normally when they get up to speed.
Honestly, though, I wouldn't worry about it too much. My pig's on a low dosage of painkiller/antiinflammatory twice daily & it really doesn't affect him much, I just have to take care of his red feet so he doesn't get bumblefoot. He's perfectly happy and able to do everything he used to. Also, your piggy is so young you won't need to worry about it for a few more years. Hope this helps. :^)