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How MACI works

The process begins with a minimally-invasive arthroscopic procedure to procure a sample of your cartilage cells (chondrocytes). This sample is then sent to a laboratory and allowed a period of time to grow.

During the MACI implant procedure, your cartilage cell sample will be embedded on a special collagen membrane, then implanted into your knee by your MACI specialist.

MACI is indicated for the repair of single or multiple symptomatic, full-thickness cartilage defects of the adult knee, with or without bone involvement. The videos are not intended to provide medical advice. Always talk to your healthcare provider with any questions. You should also talk to your healthcare provider before starting any exercise and to see if MACI may be right for you. Individual results will vary.

Watch how this works

From Your
Cells to MACI

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From your cells to MACI: A step-by-step guide

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How you rehab after the procedure is so important in your return to living life on your terms.

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Answer some quick questions to determine your level of pain and to help decide if MACI may be your next best step

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Learn more about knee pain and cartilage damage to better understand how they may be affecting your life.

Talk with real patients about their experience with MACI

Hear about real personal experiences with knee cartilage damage and MACI. The MACI Mentor Program gives you an opportunity to connect one-on-one with real people who have had the MACI procedure.

It's Your Move

To speak with a MACI Mentor, call 1-888-237-5493 or visit

Kayla, MACI patient

“My MACI procedure had a positive impact on my ability to participate in daily activities. I can now spend long hours on my feet at work with confidence, and I’m back to enjoying the activities I love.”

—Kayla, MACI patient*

*Paid testimonial by a MACI patient. Individual results may vary.

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See Kayla’s and others’ stories about how MACI has helped them get back to their active way of life.


Sign up to get information on the MACI procedure, patient support, and more with our free welcome packet.

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It's Your move

* In the SUMMIT clinical trial, MACI was shown to offer greater pain relief and improvement in function when compared to microfracture.
Improvements in pain and function were maintained with MACI at year 5
Reference: 1. Saris D, Price A, Widuchowski W et al. Matrix-Applied Characterized Autologous Cultured Chondrocytes Versus Microfracture. Am J Sports Med. 2014;42(6):1384-1394. doi:10.1177/0363546514528093

Indication and Important Safety Information

Important Safety Information

MACI should not be used if you:

  • are allergic to antibiotics such as gentamicin, or materials that come from cow, pig, or ox;
  • have severe osteoarthritis of the knee, other severe inflammatory conditions, infections or inflammation in the bone joint and other surrounding tissue, or blood clotting conditions;
  • have had knee surgery in the past 6 months, not including surgery for obtaining a cartilage biopsy or a surgical procedure to prepare your knee for a MACI implant;
  • or cannot follow a doctor-prescribed rehabilitation program after your surgery

Consult your doctor if you have cancer in the area of the cartilage biopsy or implant as the safety of MACI is not known in those cases.

Conditions that existed before your surgery, including meniscus tears, joint or ligament instability, or alignment problems should be evaluated and treated before or at the same time as the MACI implant.

MACI is not recommended if you are pregnant.

MACI has not been studied in patients younger than 18 or over 55 years of age.

Common side effects include joint pain, tendonitis, back pain, joint swelling, and joint effusion.

More serious side effects include joint pain, cartilage or meniscus injury, treatment failure, and osteoarthritis.

Please see Full Prescribing Information for more information.


MACI® is made up of your own (autologous) cells that are expanded and placed onto a film that is implanted into the area of the cartilage damage and absorbed back into your own tissue.

MACI® (autologous cultured chondrocytes on porcine collagen membrane) is made up of your own (autologous) cells that are expanded and placed onto a film that is implanted into the area of the cartilage damage and absorbed back into your own tissue.

MACI is used for the repair of symptomatic cartilage damage of the adult knee.

The amount of MACI applied depends on the size of the cartilage damage. The MACI film is trimmed by your surgeon to match the size and shape of the damage, to ensure the damaged area is completely covered.

Limitations of Use

It is not known whether MACI is effective in joints other than the knee.

It is not known whether MACI is safe or effective in patients over the age of 55 years.