I assume that being 6-7-12, you are already running.
Your surgeon should have given you some advice on this.
But, returning from injury and taking a good 3 months off of running, the advice is start slowly.
A few miles at first, then cross train. Try a one day on, one day off /cross-train(or bike, swim, strentgh train, yoga, etc.), then run. If you feel good,then after a few weeks, try 2 days in a row of running followed by a rest day or X-train day.