MACI vs. ACI: How the Third Generation ACI Repairs Knee Cartilage Skip to content

MACI vs. ACI: How the Third Generation ACI Repairs Knee Cartilage

While orthopedic surgeons have used autologous chondrocyte implantation (ACI) for decades, matrix-induced ACI (MACI) is the third and latest ACI generation to repair cartilage defects in the adult knee. What differentiates MACI from previous generations of ACI is its simplified, cutting-edge approach to chondrocyte delivery.
 

Knee cartilage regeneration before and after MACI

Effectiveness of MACI in joints other than the knee has not been established. Safety and effectiveness of MACI in patients over the age of 55 years have not been established.

 

Earlier Generations of ACI

Phase one of an ACI consists of an arthroscopy where a surgeon harvests cartilage cells, which are then treated and multiplied in a lab to form a new autologous cartilage implant. Phase two consists of implantation surgery.

The first two generations of ACI required longer, more complex implantation procedures. In implantation surgery for the first generation of ACI, a surgeon made two incisions. The first incision was to the knee and exposed the patient's cartilage damage, while the second was over the tibia and allowed the surgeon to harvest periosteum tissue. This tissue was used to shape a periosteal cover approximately the size of the patient's cartilage defect. The surgeon sutured the periosteal cover in place over the patient's cartilage defect to form a seal and inject the new chondrocytes under the cover. This procedure had variable success. The most common complication reported was periosteal hypertrophy (scar tissue) around the edge of periosteal cover.

The second generation of ACI, or collagen-covered ACI (CACI), used a biodegradable collagen membrane to implant cartilage cells rather than a periosteal cover. CACI avoided the drawbacks of the periosteal cover but had its own complications that resulted from suturing the collagen cover. This included surgical complexity, microtrauma to tissue and cell leakage.

 

How is MACI Different?

MACI, the latest advancement in ACI, delivers cells via a resorbable type I/III porcine collagen membrane that makes surgical implantation easier for surgeons. As opposed to the previous generations of ACI, the chondrocytes are applied directly to the membrane during manufacturing, simplifying the implantation process. During implantation, MACI's durable membrane is secured in place with fibrin glue rather than time-intensive and cumbersome sutures. This means the surgeon can deliver the implant with smaller incisions during a shorter, less invasive procedure. The MACI membrane's versatility means that it can be used to treat defects in multiple areas of the knee and more difficult to treat defects, including uncontained defects. Previous ACIs were limited in their indication for the treatment of cartilage defects.

The most frequently occurring adverse reactions reported for MACI (≥5%) were arthralgia, tendonitis, back pain, joint swelling, and joint effusion. Serious adverse reactions reported for MACI were arthralgia, cartilage injury, meniscus injury, treatment failure, and osteoarthritis. Please see full ISI and link to PI below.

During manufacturing, characterized cells are distributed onto the membrane using Vericel's proprietary Uniform Loading Unit (ULU), which allows for a uniform delivery of cells to cartilage defects, regardless of defect size and shape. It is dual-sided; a porous side allows cell attachment, and a smooth side aids joint articulation. This membrane can be sized to fit the exact shape and dimensions of the patient's cartilage membrane. Plus, the implant is resilient and strong; it permits sutures or suture anchor fixation when needed.

 

MACI Manufacturing

This MACI membrane is aseptically manufactured at Vericel's FDA-licensed facility. Before each procedure, rigorous assay testing is done to certify the implant's viability, identity and potency prior to product release. Following manufacturing, physicians may use a MACI implantation tray to shape the membrane to fit the patient's cartilage defect.

 

Is MACI right for your patients? Explore patient profiles.

 

Please see below for full indication and ISI.

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MACI repairs knee cartilage using your patient’s own chondrocytes

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Watch live MACI case videos with notable orthopedic surgeons.

Indication and Important Safety Information

Important Safety Information

MACI is contraindicated in patients with a known history of hypersensitivity to gentamicin, other aminoglycosides, or products of porcine or bovine origin. MACI is also contraindicated for patients with severe osteoarthritis of the knee, inflammatory arthritis, inflammatory joint disease, or uncorrected congenital blood coagulation disorders. MACI is also not indicated for use in patients who have undergone prior knee surgery in the past 6 months, excluding surgery to procure a biopsy or a concomitant procedure to prepare the knee for a MACI implant.

MACI is contraindicated in patients who are unable to follow a physician-prescribed post-surgical rehabilitation program.

The safety of MACI in patients with malignancy in the area of cartilage biopsy or implant is unknown. Expansion of present malignant or dysplastic cells during the culturing process or implantation is possible.

Patients undergoing procedures associated with MACI are not routinely tested for transmissible infectious diseases. A cartilage biopsy and MACI implant may carry the risk of transmitting infectious diseases to healthcare providers handling the tissue. Universal precautions should be employed when handling the biopsy samples and the MACI product.

Final sterility test results are not available at the time of shipping. In the case of positive sterility results, health care provider(s) will be contacted.

To create a favorable environment for healing, concomitant pathologies that include meniscal pathology, cruciate ligament instability and joint misalignment, must be addressed prior to or concurrent with the implantation of MACI.

Local treatment guidelines regarding the use of thromboprophylaxis and antibiotic prophylaxis around orthopaedic surgery should be followed. Use in patients with local inflammations or active infections in the bone, joint, and surrounding soft tissue should be temporarily deferred until documented recovery.

The MACI implant is not recommended during pregnancy. For implantations post-pregnancy, the safety of breast feeding to infant has not been determined.

Use of MACI in pediatric patients (younger than 18 years of age) or patients over 65 years of age has not been established.

The most frequently occurring adverse reactions reported for MACI (≥5%) were arthralgia, tendonitis, back pain, joint swelling, and joint effusion.

Serious adverse reactions reported for MACI were arthralgia, cartilage injury, meniscus injury, treatment failure, and osteoarthritis.

Please see Full Prescribing Information for more information.

Indication

MACI® is an autologous cellularized scaffold product that is indicated for the repair of single or multiple symptomatic, full-thickness cartilage defects of the adult knee, with or without bone involvement.

MACI® (autologous cultured chondrocytes on porcine collagen membrane) is an autologous cellularized scaffold product that is indicated for the repair of single or multiple symptomatic, full-thickness cartilage defects of the adult knee, with or without bone involvement.

MACI is intended for autologous use and must only be administered to the patient for whom it was manufactured. The implantation of MACI is to be performed via an arthrotomy to the knee joint under sterile conditions.

The amount of MACI administered is dependent upon the size (surface in cm2) of the cartilage defect. The implantation membrane is trimmed by the treating surgeon to the size and shape of the defect, to ensure the damaged area is completely covered, and implanted cell-side down.

Limitations of Use

Effectiveness of MACI in joints other than the knee has not been established.

Safety and effectiveness of MACI in patients over the age of 55 years have not been established.