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.

Cartilage regeneration - knee

The surgeon makes a tiny, quarter-inch incision 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 a patient prevent a partial or total knee replacement. It is also used to treat pain in the knee from cartilage injuries, as well as:

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

Risk for any surgery include:

• Bleeding
• Infection

Risks for microfracture include:

• Increased stiffness of the knee bone
• 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.

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 to 8 hours per day for several weeks. The exercises are increased over time until the patient regains full range of motion. Such exercises are believed to speed up cartilage regeneration.

The patient will be told to keep their weight off the affected joint for 6 to 8 weeks. Crutches will be needed.

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

Miller BS, Steadman JR, Briggs KK, Rodrigo JJ, Rodkey WG. Patient satisfaction and outcome after microfracture of the degenerative knee. J Knee Surg. 2004 Jan;17(1):13-7.

Orthopaedic knowledge update. In: Pellicci PM, Tria AJ, Garvin KL eds. Hip and Knee Reconstruction. Rosemont, Illinois: American Academy of Orthopaedic Surgeons; 2000.

Johnson, D. Articular Cartilage Update. Program and abstracts of the American Academy of Orthopaedic Surgeons 70th Annual Meeting; February 5-9, 2003; New Orleans, Louisiana.