Revolutionizing Knee Cartilage Repair: The Matrix-Induced Autologous Chondrocyte Implantation (MACI) Procedure and Its Impact on Regenerative Medicine

MACI is a game-changing treatment for managing knee pain. Keep reading to learn about the procedure and why it is fast becoming the gold-standard treatment to help your knee.

What is the MACI Procedure?

The MACI Procedure (matrix-induced autologous chondrocyte implantation) is a minimally invasive orthopedic surgery indicated for cartilage damage in the knee that causes pain. The procedure is an autologous stem cell therapy, which means that the stem cells used in MACI are harvested from your own body.

Knee pain is quite common, and the most common cause of it is cartilage damage. If your knee is painful, an orthopedic specialist such as our providers at Dr. Burke Orthopedics can accurately diagnose the cause. If they determine you are having pain because of damaged cartilage within the joint, your doctor may recommend that you have the MACI procedure.

The procedure consists of a 2-step process. The first phase involves extracting a sample of chondrocytes from your knee joint, which are the precursor cells needed to grow new cartilage. The sample, harvested from the knee in a non-weight-bearing position, is done arthroscopically.

The extracted chondrocyte cells are then sent to a lab to be specially treated and grow new cartilage. After about a month, the new cartilage can survive on its own and your MACI implant is created.

The second step of the process consists of surgically inserting your MACI implant over or in place of the damaged cartilage. MACI implants are flexible and strong, and they can be trimmed to a custom fit of the damaged cartilage.

A High Success Rate, and What That Means

The success rate of this procedure is 80-85%. Patients who have undergone the procedure are regularly asked to rate their percentage of improvement in function and symptoms. 0% means no improvement following surgery. 100% improvement means that all pain and function limitations experienced before surgery are now resolved.

Not many surgeries reach that level of success. A higher rate of success was confirmed in a study by SUMMIT. The study followed up with patients both 2 and 5 years after surgery when compared to microfracture.

Is MACI Right for You?

MACI is a wonderful option available to you to choose over more invasive surgeries that need longer recovery times. Recovering after this procedure is less painful than many other orthopedic surgeries.

The safety and efficacy of the MACI Procedure have not been determined for patients outside of 18-55 years of age.

Also, some contraindications exist that you should consider before opting for this procedure.

  • Severe osteoarthritis of the knee or other inflammatory conditions
  • Infections in the knee joint or surrounding tissue
  • Abnormal blood clotting conditions
  • Knee surgery in the past 6 months, not including surgery for extracting a sample of your cartilage for a biopsy or having had a surgical procedure to prepare your knee for a MACI implant.
  • Knowing you will be unable to follow a prescribed rehabilitation program after surgery.


  1. Saris D, Price A, Widuchowski W, Bertrand-Marchand M, Caron J, Drogset JO, Emans P, Podskubka A, Tsuchida A, Kili S, Levine D, Brittberg M; SUMMIT study group. Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture: Two-Year Follow-up of a Prospective Randomized Trial. Am J Sports Med. 2014 Jun;42(6):1384-94.
  2. Brittberg M, Recker D, Ilgenfritz J, Saris DBF; SUMMIT Extension Study Group. Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture: Five-Year Follow-up of a Prospective Randomized Trial. Am J Sports Med. 2018 May;46(6):1343-1351.

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