Microfracture Surgery for Cartilage Damage

Microfracture is a surgical option used in the treatment of areas of damaged cartilage. When a patient has a small area of damaged cartilage (not widespread arthritis), microfracture may be performed in an attempt to stimulate new cartilage growth. Microfracture is most often performed inside the knee joint, although it has also been used for treatment in other joints including the hip, ankle, and shoulder.

A microfracture procedure creates small holes in the bone. The surface layer of bone, called the subchondral bone, is hard and lacks good blood flow. By penetrating this hard layer, a microfracture allows the deeper, more vascular bone to access the surface of the joint. This deeper bone has a more rich blood supply, and the cells can then get to the surface layer to stimulate cartilage growth.

There are some people who are good candidates for microfracture surgery and others who are not.

A microfracture is performed as part of arthroscopic knee surgery. Other joints can be treated similarly, also by arthroscopic surgery. Microfracture has been performed in the ankle, shoulder, hip, elbow, and other joints. While it is by far most commonly performed for knee joint problems, it can also be used effectively for problems in other joints in the body.

First, the area undergoing microfracture is prepared by removing any loose or damaged cartilage. Ideally, the area undergoing microfracture will be less than about 2 centimeters in diameter and have good, healthy surrounding cartilage. Then, a small, sharp pick (awl) is used to create the small microfracture holes in the bone.

The number of microfractures created depends on the size of the joint are being treated. Most patients with a 1- to 2-centimeter area of damage require five to 15 small microfracture holes in the bone.

The penetration of the outer layers of bone allows blood and stem cells to form a clot in the area of the cartilage defect. These cells have the ability to form a cartilage layer within the defect. Essentially the body is able to repair the damaged area of cartilage by stimulating blood flow to the defect.

One of the keys to successful treatment is appropriate rehabilitation following the microfracture surgery. Rehabilitation must protect the area treated by microfracture as well as maintain the strength and motion of the knee joint. As a result, most patients need to use crutches after surgery, often a knee brace will be recommended, and in some situations, a motion machine to bend the knee may be used.

Microfracture can be an excellent procedure, providing substantial pain relief when done in the right patient. One of the concerns with microfracture is that it does not stimulate the growth of normal joint cartilage.

There are many types of cartilage, and one of these (hyaline cartilage) is normally found on the joint surface. Microfracture stimulates the growth of another type of cartilage commonly found in scar tissue (called fibrocartilage). Unlike hyaline cartilage, fibrocartilage does not have the same strength and resiliency of cartilage normally found in a joint. Therefore, there is a chance that the cartilage stimulated by a microfracture procedure will not stand up over time.

Microfracture surgery is popular because it is safe, relatively easy to perform, and comparatively inexpensive to other cartilage stimulation surgical procedures.

But does it work? The results of microfracture surgery have been investigated many times. In general, people who undergo microfracture surgery do reasonably well in the short to mid-term.

There are questions, however, about the durability of microfracture repair, and most surgeons agree that the cartilage that heals within a microfracture defect is not nearly as durable as normal cartilage.

Patients who are good candidates for microfracture could also be good candidates for other treatments for cartilage defects of the knee. These alternatives include cartilage transfer and cartilage implantation. 

However, the success of these surgical options has been shown to be no better than microfracture, while the risks and costs of microfracture are dramatically less.

Microfracture surgery is generally considered the first-line treatment for cartilage damage in the knee joint. Some of these other surgical options are generally done for athletes who have failed to improve after microfracture surgery.