Are there many cases of a non displaced lateral malleolus fracture treated conservatively in cast and non weight bearing, then aircast partial weight bearing, having to result in orif ?

Possible: It is entirely possible to initially treat a fractured ankle with immobilization and then have to perform surgery due to non healing.

Occasionally: A lateral malleolus fracture treated this way is frequently considered stable but may border the line between stability and instability. In these instances such a fracture might displace sufficiently to warrant operative fixation of the bone.

Fx ankle: If stable and not displaced a cast and non weight bearing should be enough to avoid orif.