Microfracture surgery is a treatment option for people who have cartilage damage within a joint. Cartilage injuries are difficult for the body to heal. The type of cartilage that provides smooth motion at a joint surface is called articular cartilage. Articular cartilage gets its nutrition from the surrounding fluid of the joint. It does not have a blood supply that brings nutrients to the cartilage cells. For that reason, when there is a cartilage injury, there is little the body can do to heal that injury. Normally when tissues within the body are injured, it is the blood supply that delivers the critical nutrients to heal that injury. Without having this type of blood flow, articular cartilage injuries generally do not heal themselves.
Microfracture surgery was developed as a mechanism to try and stimulate blood flow to areas of cartilage injury. Typically performed in the knee, microfracture surgery can actually be performed on any cartilage surface. Essentially, a microfracture surgery creates a bleeding response in an area where the cartilage has been damaged. Either by punching small holes into the bone underneath the cartilage surface or by drilling small holes in the bone, a microfracture creates a pathway where blood can get to the area of cartilage injury. Once that blood flow can reach that area, a healing response can occur. The normal articular cartilage does not heal in this area, but the body can create a healing response of a different type of cartilage called fibrocartilage. This is the healing response that is seen in microfracture surgery.
Rehabilitation after microfracture surgery of the knee joint is the key to effective treatment. While the surgical procedure can be performed perfectly, without the proper attention to rehab after surgery, the results are unlikely to be successful The exact rehabilitation from microfracture surgery depends on the size and location of the area of cartilage damage.
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.
Results of Surgery
Microfracture has been shown to be a very effective treatment for appropriate patients with knee cartilage damage amenable to this types of surgery. Reports in the literature are variable, but about 80% of patients find improvement in their symptoms. The results from surgery tend to be best in the early years after the procedure, and there is evidence that the results can diminish over time.
The reason is thought to be the result of the type of cartilage that grows when a microfracture surgery is performed. Unlike the normal cartilage of the knee joint, called hyaline cartilage, microfracture stimulates the growth of fibrocartilage. Much like scar tissue on the skin, the appearance and the durability of this scar cartilage is not the same as normal cartilage. Therefore, a few years after microfracture surgery has been performed, some studies show a deterioration of the results with fewer patients reporting successful outcomes.
Numerous studies have also been performed to compare microfracture surgery to other treatment options for cartilage damage. These other options include autologous chondrocyte implantation (ACI) and osteochondral autograft transplantation (OATS). In general, no procedure has been shown to have superior results to another, and since the risks and costs of microfracture are significantly less, and the rehab much easier, microfracture is generally considered the first-line treatment. Other options such as ACI and OATS are reserved for patients who fail to improve after microfracture surgery.
A Word From Verywell
Microfracture surgery can be an effective treatment for people who have sustained cartilage injuries. In order for microfracture surgery to be effective, the rehabilitation that follows must be performed as instructed. By performing too much activity following surgery, the effects of microfracture may be diminished, and the cartilage healing that takes placed may not be adequate. For that reason, it is critical to follow your surgeon's instructions when recovering from microfracture surgery.