The amount of weight put on the area of microfracture must be limited. This allows the cells to grow in develop in the area that underwent the microfracture treatment.
How to limit weight on the area of the microfracture depends on the location of the injury. When the microfracture is on the top of the shin bone (tibia) or the end of the thigh bone (femur), weight is limited by having a patient use crutches. When the microfracture is on the kneecap (patella) or within the groove for the patella (trochlea), knee motion must be limited because bending the knee will cause compression on this area.
Weight bearing is usually limited for 6 to 8 weeks, then gradually progressed over time. It may take 4 to 6 months before one can return to sport activities, and even longer to return to competition. Professional athletes may be sidelined up to a year after microfracture surgery.
Range-of-motion is usually initiated early on after surgery. However, if the area of microfracture treatment is on the kneecap or within its groove, then motion will be limited for several weeks.
Some surgeons will elect to use a CPM, or a motion machine, to help patients move their knee early on after microfracture surgery. The use of the CPM has not been shown to be any better than range-of-motion exercises, but some surgeons will still elect to use the machine.
The reason for starting motion as early as possible is that the movement helps stimulate healthy cartilage growth.
Mitheofer K, et al. "High-Impact Athletics After Knee Articular Cartilage Repair" Am. J. Sports Med., Sep 2006; 34: 1413 - 1418.