Limiting physics between two objects

Is it possible to set it so two objects that are both affected by physics are a fixed distance (On a 2D plane) between each other programmatically? I basically want it so they are always 10 units away from each other. They are currently connected by a configurable joint which I can't seem to make work with what I require, I suppose I could do it like this but i'm not sure what to put in the //DoSomething bit:

if(Vector2.Distance(PointA, PointB)<10 || Vector2.Distance(PointA, PointB)>10){
// DoSomething
}

Many thanks in advance!!!