Knee microfracture surgery is a common technique used to repair damaged knee cartilage, the material that helps cushion bones at the joints. It is frequently performed on athletes.

The surgeon makes a tiny, quarter-inch surgical cut on the affected knee and inserts a long thin scope (arthroscope). This scope allows the surgeon to work directly on the joint area.

The surgeon uses an ice pick-like tool called an awl to drill very small holes (“microfractures”) into the bone near the defective cartilage. The injury prompts the body to make new, replacement cartilage. Bone marrow seeps out of the holes, creating a blood clot that releases cartilage-building cells.

Microfracture surgery can help avoid a partial or total knee replacement. It is also used to treat pain in the knee from cartilage injuries, as well as:

• Degenerative chondral lesions of the knee
• Early arthritis of the knee
• Lesions on the kneecap
• Traumatic injuries to the cartilage

Risk for any surgery include:

• Bleeding
• Infection

Risks for microfracture include:

• Cartilage breakdown. The new fibrocartilage created by microfracture surgery is less durable than the body’s original cartilage, and can break down after a few years.
• Increased stiffness of the knee bone

Most patients improve after surgery, and can return to sports (or other intense activities) in about 4 months.

Physical therapy may begin in the recovery room immediately after surgery. A continuous passive motion (CPM) machine gently flexes and extends the leg for 6 - 8 hours per day for several weeks.

The exercises are increased over time until you regain full range of motion. Such exercises are believed to speed up cartilage regrowth.

You will need to keep your weight off the affected joint for 6 - 8 weeks. You will use crutches to get around.

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.