What Is a MACI® Implant? A Dive into the MACI® Procedure

MACI® (Matrix-induced autologous chondrocyte implantation) Procedure implant is a revolutionary stem cell therapy for the treatment of knee pain caused by cartilage damage. It is a minimally invasive surgical option that uses stem cells from your own body.

MACI Implant Procedure

MACI implant is an acronym derived from Matrix-Induced Chondrocyte Implantation. “Matrix-induced” refers to where the cells ultimately used for regeneration and reparation of the damaged cartilage live for a while. Healthy chondrocyte cells are harvested from your knee and placed onto a collage matrix where they to grow into fresh, new cartilage. When mature enough, these newly grown cartilage cells grown on the collage matrix become your MACI implant.  

The MACI Procedure Process

MACI is a simple two-step process. The first step involves the harvesting of a sample of healthy chondrocytes from your knee. Chondrocytes are the precursor cells responsible for the formation of cartilage. This sample is extracted arthroscopically, meaning that your surgeon inserts a tiny camera into the knee in a non-weight-bearing position via a very small incision.

The camera displays an image of the inside of your knee onto a monitor that guides your surgeon. This stage of the procedure takes about half an hour on an outpatient basis, and you will go home the same day.

The extracted sample of chondrocytes is then shipped to a lab, specially treated, and grown into new, healthy cartilage tissue.

Around a month later, the sample of cells extracted from your knee reaches maturation and are healthy, new cartilage cells. The mature sample is your MACI implant. It is then shipped back to your surgeon and implanted into your knee. The implant is very strong and flexible and can be cut to match the exact shape and size of the damaged cartilage. 

The second phase of this procedure is also performed on an outpatient basis and does not require a night in the hospital.

Recovery After the MACI Implant

As your MACI implant resorbs back into your tissue, you will find that recovery from this procedure is easier and less painful than many other orthopedic surgeries.

After completion of the second phase of the procedure, you will wake up wearing a brace on your leg that is locked in a straightened position to protect the new implant. You need to wear this brace for about 6 weeks.

The brace can be unlocked for bending the knee when sitting, but there will be a limit on the amount of weight you can bear on the leg when standing. Usually, some weight bearing is allowed as tolerated.

Following the first days of recovery, you will need to go through a course of physical therapy to regain full range of motion and strength. Your physical therapist individualizes your rehab program to your unique needs. Each person will experience a different rate of healing, but the average time frame for recovery that one can expect is liberation from the brace and full range of motion and weight-bearing in 8 to 12 weeks. Full recovery generally takes 9 to 12 months.

Expectations After the MACI Implant

Complications arising from this procedure are rare. Barring any unforeseen stumbling blocks, after full recovery has taken place, you should expect a pain-free, full return to function and sport.