Cartilage injuries in the knee are common.  Treatment of cartilage injuries in the knee are constantly evolving. A microfracture surgery is one of the useful surgical options available to heal knee cartilage injuries . A microfracture is a knee surgery technique used to repair defects or holes in cartilage by making multiple small holes in the surface of the joint.  Those holes allow bone marrow stem cells to enter the cartilage defect. For small cartilage  injuries a microfracture is a reasonable repair option. Ultimately, the type of treatment we recommend for your cartilage injury will depend on many factors including the size of the damaged area, and the quality of the remaining cartilage around it.

The knee is a complex structure. The knee is composed of 3 bones, 4 major ligaments, tendons, cartilage and the two cushions we call the menisci.  In patients who suffered an injury to the cartilage on the end of the bone, a hole or defect in that cartilage might develop.

That means that that area of the knee is missing the cartilage or cushioning and will most certainly go on to develop significant osteoarthritis, which could eventually lead to a knee replacement.

Cartilage holes or defects in the could be due to a traumatic defect (car accident or fall), or it could be due to early arthritis.  Either way, it is essential that we try to rebuild that cartilage to minimize the risk of further arthritic or degenerative  changes.

One of the most commonly utilized procedures is a Microfracture … what is knee microfracture surgery?  Let’s move on…

microfracture knee surgery

Notice the smooth white substance — this is normal appearing cartilage.

What is Normal Cartilage?

Normal cartilage is a firm, rubbery substance that coats the end of our thigh bone, and the top of the shin bone — creating a thick ultra-smooth layer so that the knee can bend without friction, pain, catching, clicking or other troublesome issues.  The picture above shows this clearly.  The surface is smooth, and free of any signs of cartilage damage or cartilage degeneration.

How is Knee Cartilage Injured?

The cartilage in our knee is subject to the everyday stresses we put on our knee.    If you are a contact athlete, involed in a serious fall or accident, you will suffer a traumatic injury to the cartilage which may cause it to separate from the bone.  By far the most common cause of cartilage damage and deterioration is because of aging and genetics.  In the past we had very few options in dealing with these defects or injuries.  A microfracture is but one of the many options we have to try and minimize your pain and attempt to have the damaged area regrow cartilage.

knee cartilage injury

Notice how the white cartilage has separated from the bone creating a hole in the cartilage

What is a Microfracture?

A microfracture is but one of the many techniques orthopedic surgeons can perform to try and get the body to repair itself and regrow the area of cartilage loss.  We all know about stem cells. We all know about bone marrow.  These cells have the ability to regenerate many of the tissues in our body.  If placed in the knee, they turn into cartilage cells and can fill in a hole in the cartilage.  During a microfracture, we clear off the loose pieces of cartilage and debris from the area where the cartilage is missing and then we make small holes or punctures in the bone (1-2 millimeters).  Those holes communicate with the bone marrow where the stem cells are located.

What is my recovery from microfracture surgery?

The recovery from microfracture surgery is long.  Why?  The stem cells that enter the knee through those holes and coat the hole or cartilage defect need time to “work their magic” .  The stem cells need to settle into the hole.  Then they need to multiply and divide.  They need to form a layer over the cartilage defect.  Then they need to start making cartilage.  It’s like making Jello 🙂 . When you first combine everything you have liquid that you can drink in a straw.  After a while and some time in the refrigerator the jello hardens into something we can eat.  Over time (few months) those new cartilage cells will turn into cartilage cells and start to make cartilage to eliminate the hole … and improve your pain and quality of life!

Here are pictures which show exactly what we do when we perform a microfracture.  

  • First…evaluate the defect or hole. 
Microfracture procedure

Note the cartilage defect (pinkish color)







  • Prepare the defect … remove debris: 

Cartilage defect prepared







  • Microfracture for cartilage defect

    Notice the small holes… they really are small =1-2mm

    Perform the microfracture: 

  • Stem cell entering the knee through the microfracture holes:


Notice the bone marrow cells and stem cells entering the knee




Now we wait… those cells have to turn into cartilage cell… they need to smooth out within the hole and they need to create the actual cartilage.  This process will take months.  That’s simple biology.  We are performing PRP or platelet rich plasma injections at the same time to try to enhance the recovery process … and we are now able to harvest bone marrow from your hip area which should further enhance the response and the quality of the ultimate repair.  

Recent advances (2016) show that a newer procedure might be more effective than a microfracture.  Click here to read more.

Here is a recent before and after case…. In the first picture you will see the cartilage defect of loss of cartilage… and in the second picture you will see what this area now looks like only 5 months later!

Missing Cartliage

Note the large hole in the cartilage

Cartilage restoration






Recommended follow up reading:

Cartilage defects

PRP for arthritic disorders:

Recovery for a PRP injection 

Treatment options for early arthritic changes