My 3 year old had a spiral fracture in her leg shortly after her third birthday. No traction needed thankfully, but was in a cast from foot to hip
Is the child still in a car seat? He won't be able to rear face, there's nowhere for the leg to go. Even forward facing is difficult there's not a lot of room between the leg and seat in front. May be necessary for the child to be behind the passenger seat with the passenger seat pulled right forward. The only place we went in the car was the appointments for her leg.
She actually adapted really well, it was difficult to keep her off the leg until she was allowed to walk on it. She did a lot of bum shuffling, and hopping and leg dragging. She found what was easiest for her. When out and about we put her in a trike which has a parent handle to push her,l. We made a makeshift sling for her leg underneath the handles so her foot was up out the way.
She did need help getting on and off the toilet, but at the time she needed a footstool to reach the toilet.
I'm not sure about when the leg has been in traction, but we got a waterproof cover for bathing and showering and playing with mucky things. We had to measure the leg to get a proper fit and the hospital gave us a leaflet with recommended brands.
Also have a think about clothing. Tights were a no go, most jeans were a no go, most leggings were a no go. Most things just simply didn't fit over the cast. We had to go out and buy some baggy jogging bottoms. Also think about things to cover the foot. We got some socks several sizes too large for my daughter.
We found she adjusted quite well but did get frustrated at times