Knee Microfracture Surgery

Knee microfracture surgery is performed to repair worn-out, loose, or damaged cartilage that surrounds the knee bone.

What is Knee Microfracture Surgery?

Knee microfracture surgery is performed to repair loose or damaged cartilage. A surgeon makes a quarter-inch incision on the affected knee. A small camera is inserted into the damaged knee to view the joint. A sharp pick (awl) is then used to make small microfracture holes, which cause new cartilage to generate. The drilled holes are near the defective cartilage and the number of holes is determined by the size of the area that needs to be treated. Most patients will have a 1 to 2 centimeter area of damaged cartilage that will require 5 to 15 small holes to be drilled in the bone.

The surface layer of the damaged bone (subchondral bone) is hard and lacks good blood flow. The microfracture holes allow the deeper bone marrow to access the surface layer. The deeper bone marrow has more blood supply, and the cells can then get to the surface layer and create a blood clot that releases cartilage-building cells.

Who is a Candidate?

Typical candidates for knee microfracture surgery are people who:

  • Have limited areas of cartilage damage.
  • Are active and cannot participate in sports or physical activities because of symptoms.
  • Have pain or swelling caused by the damaged area of cartilage.
  • Don't have significant arthritis in the joint.


  • A partial or total knee replacement
  • Traumatic injuries to the cartilage
  • Progressive arthritis of the knee

Post-Surgery Rehabilitation

After having microfracture surgery, patients may need to keep their weight off the treated joint for 6 to 8 weeks. Most patients can return to sports and other activities in 4 to 6 months.

Physical therapy will start immediately after surgery. A continuous passive motion (CPM) machine may be used to regain the patient's range of motion in their knee. Treated patients will gradually add low-impact exercises to their daily activities to speed up cartilage regeneration.

Limiting the amount of weight on the treated knee depends on the location of the injury. When the microfracture is on the top of the shin bone (tibia) or the end of the thigh bone (femur), crutches are needed to bear weight. When the microfracture is on the kneecap (patella) or within the groove for the patella (trochlea), knee motion is limited to prevent bending of the knee and a wheelchair might be needed.