After a knee fracture, whether treated conservatively or surgically, if the fracture end is relatively stable or the surgical wound is relatively stable, you can use a double crutch to walk on the ground and exercise functionally, but the injured limb is not able to bear weight and the main force is on the healthy limb. If you want the injured limb to be able to use a single crutch for weight-bearing, it takes at least 4-6 weeks, and you must review the photos to see the growth of bone scabs before you can give up a crutch and use a single crutch to give the injured limb part of the force to gradually walk activities and functional exercises.