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 knee arthritis), microfracture may be performed in an attempt to stimulate new cartilage growth.
How does microfracture work?
A microfracture 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 layer. This deeper bone has more blood supply, and the cells can then get to the surface layer and stimulate new cartilage growth.
Who is a good candidate for microfracture?
• Patients with limited areas of cartilage damage
• Patients who are active and cannot participate in their sport or activity because of symptoms
• Patients with pain or swelling caused by the damaged area of cartilage
Who is not a good candidate for microfracture?
• Patients with widespread arthritis of the joint
• Patients who are inactive
• Patients unwilling to participate in rehabilitation following microfracture
Does microfracture work well?
Yes, in properly selected and compliant patients. 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 types (hyaline cartilage) is normally found on the joint surface. Microfracture stimulates the growth of a type of cartilage commonly found in scar tissue (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 break down over time.
How is a microfracture procedure performed?
A microfracture is performed as part of an arthroscopic knee surgery. 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 is used to create the small microfracture holes in the bone. The number of microfracture holes created depends on the size of the lesion being treated. Most patients with a 1 to 2 centimeter area of damage require 5 to 15 small holes in the bone.
Appropriate rehabilitation following the microfracture surgery is an essential part of the recovery process. In general, most patients use crutches and are unable to put weight on the effected knee for approximately 6 weeks following surgery. This is followed by progressive strengthening exercises. Rehabilitation must protect the area treated by microfracture as well as maintain the strength and motion of the knee joint.
Are there alternatives to microfracture?
Yes. Patients who are good candidates for microfracture could also be good candidates for other treatments for cartilage defects of the knee. These alternatives include articular cartilage transplantation and cartilage implantation.