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Patient Instructions

Knee microfracture surgery is a common procedure used to repair damaged knee cartilage. Cartilage is the material that helps cushion the area where bones meet in the joints. Often, athletes have this procedure.

Three different types of anesthesia may be used for knee arthroscopy surgery:

• Your knee may be numbed with painkilling medicine, along with medicines to relax you
• Spinal (regional) anesthesia
• General anesthesia, where you will be unconscious and pain-free.

The surgeon will make a 1/4-inch-long incision (cut) on your knee.

• Then the surgeon will insert a long, thin device called an arthroscope through this incision. The arthroscope is like a camera. It is attached a video monitor in the operating room. It allows the surgeon to look inside your knee and work directly on the joint area. See also: Knee arthroscopy
• The surgeon uses a small pointed tool called an awl to make very small holes called microfractures (tiny breaks) in the bone near the damaged cartilage.
• The holes the surgeon makes in your bone release the cells in your bones that build new cartilage. Your body then builds new cartilage to replace the damaged cartilage.

Microfracture surgery is done on people who have small amounts of damage in the cartilage of their knee joint and on the underside of their kneecap. This surgery can help people avoid the need for a partial or total knee replacement. It is also used to treat pain in the knee from cartilage injuries.

Risks for any anesthesia are:

• Allergic reactions to medicines
• Breathing problems The risks for any surgery are:
• Bleeding
• Infection
• Blood clot

Risks for microfracture surgery are:

• Cartilage breakdown over time. The new cartilage made by microfracture surgery is not as strong as the body’s original cartilage. It and can break down after a few years.
• Increased stiffness of the knee.

Always tell your doctor or nurse what drugs you are taking, even drugs, supplements, or herbs you bought without a prescription.

During 2 weeks before your surgery:

• Two weeks before surgery, you may be asked to stop taking drugs that make it harder for your blood to clot. These include aspirin, ibuprofen (Advil, Motrin), naproxen (Naprosyn, Aleve), and other similar drugs.
• Ask your doctor which drugs you should still take on the day of your surgery.
• If you have diabetes, heart disease, or other medical conditions, your surgeon will ask you to see your doctor who treats you for these conditions.
• Tell your doctor if you have been drinking a lot of alcohol, more than 1 or 2 drinks a day.
• If you smoke, try to stop. Ask your doctor for help. Smoking can slow down wound and bone healing.
• Always let your doctor know about any cold, flu, fever, herpes breakout, or other illness you may have before your surgery.

On the day of your surgery:

• You will usually be asked not to drink or eat anything for 6 to 12 hours before the procedure.
• Take your drugs your doctor told you to take with a small sip of water.
• Your doctor or nurse will tell you when to arrive at the hospital.

Physical therapy may begin in the recovery room right after surgery. A continuous passive motion machine (CPM) gently exercises your leg for 6 to 8 hours a day for several weeks. This machine is usually used for 6 weeks after surgery. Ask your surgeon how long you will use the CPM machine.

Your exercises will increase over time until you regain full range of motion in your knee. These exercises may speed up the new cartilage growth.

You will need to keep your weight off your knee for 6 to 8 weeks. You will need crutches to get around.

Many people improve after this surgery. Many can return to sports or other intense activities in about 4 months. Athletes in very intense sports may not be able return to their former level of competition.

Results are best when this surgery is done on people younger than 40 whose cartilage injury is recent. It is also most successful for small amounts of damage in the knee cartilage.

Cartilage regeneration - knee

Ritchie PK. Surgical management of cartilage defects in athletes. Clin Sports Med. 2005 Jan;24(1):163-74.

Williams RJ 3rd, Harnly HW. Microfracture: indications, technique, and results. Instr Course Lect. 2007;56:419-428.

Kreuz PC, Erggelet C, Steinwachs MR, Krause SJ, Lahm A, Niemeyer P, et al. Is microfracture of chondral defects in the knee associated with different results in patients aged 40 years or younger? Arthroscopy. 2006;22:1180-1186.

Updated by: C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Dept of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.