Four months back, I had met with an accident in which I broke my femur (thigh bone) the longest, most-weight bearing bone. This was the my first fracture in life(!), the earlier ones being just ligamant, cartilage ruptures and all but not a fracture. (I have had all the variety :-))

Now the first thing, immediately as the fracture happens, is a good first aid. First aid people are required to sew wounds first hand and no one gets them redone after reaching the real-hospital if they do it in an ill-fashioned way.

After the (internal/external) fixation of the bone, one should be careful enough what the doctor wants him to do. Generally they ask you to keep your muscles alive by tightening-loosening your leg. And mind it that is big enough a goal, one should do it more than often than the doctor has prescribed. If you don't, you might fall trap of muscle spasms which occur when one tries to put pressure on a non-exercised muscle.

Then your diet, must have calcium building components. There is no need of calcium tablets (they are needed for women above 45 years). Follow a diet chart which provides you more than MORE THAN 1000 mg (for a normal person) of calcium. Just forget about taste of food etc, there is a fair chance you might get bored with the nutritional products you eat but just ignore it and keep following a diet full of calcium products.

Refer to - http://www.healthsystem.virginia.edu/internet/digestive-health/nutrition/calcium1.cfm

Exercise at your ease. Put a little more strain each day without overstraining yourself. Dont relax it too long, exercise it every 2-3 hours with appropriate limber-down as well. It is thing which would heal very slowly. One wont be able to find the difference in his activities daily but on a weekly basis. And avoid any fall and practise to keep a check on your reflexes. If an object falls, let it fall but dont move your leg suddenly as it might displace the bone.

More for exercising -
http://sportsmedicine.upmc.com/InjuriesFemurFractureRehab.htm

Recommended from my experience -
I month - Total rest of the leg. Painkillers/Tightening(exercising)/Calcium Diet the muscles (very important). After the stitches are removed, one may start bathing. Physiotherapy startz after 4-5 days of the stitch cutting ceremony. Walking with the help of walker or crutches with 25% weight on the fractured leg.
II month - Physiotherapy & a good calcium diet. But very very slowly. Exercising it heavily would spoil your muscles.
III month - Start walking with the help of Stick. Take help from Physio. One holds the stick in the opposite hand of the fractured leg.
IV month - Strong Diet and Strong exercises with weights on the leg. Try walking by self as you feel comfortable. There would be pain when muscles come into action after long hours of sitting etc.

Healing a leg bone is a long slow process. One starts getting desperate at the end but maintain your cool and take care.