Convalescing at home - Slow & Steady
In the case of orthopedic limb surgery, if your pet is able to walk on the affected leg, this does not mean the bone is mended. The internal hardware is generally taking the entire load. If the load is too much, the hardware or the bone can break.
Excessive load could come from jumping off a chair or table. Lighter loads such as running and playing applied over many repetitions, can weaken the hardware and cause it to break.