Knee Microfracture Surgery
Microfracture surgery of the knee is an articular cartilage repair surgical technique that works by creating tiny fractures in the underlying bone. This causes new cartilage to develop from a so-called super-clot.
Microfracture surgery has gained popularity in sports in recent years; numerous professional athletes including members of the NBA (most notably Andrew Bogut, Anfernee Hardaway, Jason Kidd, Greg Oden, Allan Houston, Kenyon Martin, Tracy McGrady, Chris Webber and Amar’e Stoudemire, MLB (Jeff Clement), Matt Kemp, Derek Holland, NFL and NHL players have undergone the procedure.
The microfracture procedure uses the body’s own healing abilities and provides an enriched environment for tissue regeneration of chondral defects, which are damaged areas of articular cartilage of the knee. The surgery is quick – typically lasting between 30–90 minutes – minimally invasive, and can have a significantly shorter recovery time than an arthroplasty (knee replacement).
The Surgical Procedure: Microfracture
The microfracture procedure is done arthroscopically. An orthopedic surgeon visually assesses the defect and performs the procedure using special instruments that are inserted through three small incisions on the knee.
After assessing the cartilage damage, any unstable cartilage is removed from the exposed bone. The surrounding rim of remaining articular cartilage is also checked for loose or marginally attached cartilage. This loose cartilage is also removed so that there is a stable edge of cartilage surrounding the defect. This process of thoroughly cleaning and preparing the defect results in optimum surgical outcomes.
Multiple holes, or microfractures, are then made in the exposed bone about 3 to 4mm apart. Bone marrow cells and blood from the holes combine to form a “super clot” that completely covers the damaged area. This marrow-rich clot is the basis for the new tissue formation.
The microfracture technique produces a rough bone surface that the clot adheres to more easily. This clot eventually matures into firm repair tissue that becomes smooth and durable. Since this maturing process is gradual, it usually takes two to six months after the procedure for the patient to experience improvement in the pain and function of the knee. Improvement is likely to continue for about 2 to 3 years.
Following rehabilitation and physical therapy, which begin immediately after the microfracture procedure, most patients return to normal activities after 6 to 8 weeks. Athletes can resume sports that involve pivoting, cutting, and jumping approximately 4 to 6 months after a microfracture procedure.
What are the signs and symptoms of an articular cartilage injury that may be treated with the microfracture technique?
- Intermittent swelling – Loose fragments floating in the knee can cause swelling to occur.
- Pain – Pain with prolonged walking or climbing stairs.
- Giving way – The knee may occasionally buckle or give way when weight is placed upon it.
- Locking or catching – Loose, floating pieces of cartilage may catch in the joint as it bends, causing the knee to lock or have limited motion.
- Noise – The knee may make noise (called crepitus) during motion, especially if the cartilage on the back of the kneecap is damaged. This noise is often described as “snap, crackle, and pop”.