Clean break of my right femur courtesy of a drunk driver when I was 7 years old (plus the lovely scar on my chin from where a bit of car cut it to the bone, which was a triumph of plastic surgery given how much of a mess it was at the time). Spent the swelteringly hot summer of '87 in traction (it didn't need to be pinned), mostly in an isolation room[1] with just a Commodore 64 for company, and many months learning to walk again afterwards - it was ages before they'd allow me to bear weight. I did an awful lot of swimming, which the physios were extremely enthusiastic about, and got to skive copious amounts of school for the purpose.
Obviously this sort of thing heals much better in children, and I could barely ride a bike at that age, so no experience there. Swimming is a good way to maintain fitness and exercise a leg that isn't rated for weight-bearing, though. I recommend it.
The only long-term effect has been the difference in leg length, which became more of a problem in my early teens as I grew. Watch out for that (though presumably it's less of an issue if it's pinned), it can cause all sorts of knee and lower back fun, depending on how you walk/stand, and makes optimal bike setup a bit interesting.
[1] I was about the only person on the children's ward who *didn't* come down with the mumps, so they put me in isolation. This was tedious, but on balance worth it for the less draconian bedtime rules.