MACI articular knee cartilage repair using a patient's own cells Skip to content

Knee cartilage injuries will often get worse with time if left untreated

In patients undergoing cell-based knee cartilage restoration, lesions can progress and new lesions can form as time between cartilage biopsy and implantation increases.1 If conservative treatment has not worked to relieve pain associated with knee cartilage damage, MACI may be an appropriate treatment option.

Cartilage defect expansion1

0.6 cm² mean change in defect size between biopsy & implantation

0.11 cm² increase in defect expansion per month delay to implantation

New high-grade cartilage defects1

16.2% of patients developed a new high-grade cartilage defect

155 days mean time between cartilage biopsy & implantation

Cartilage damage
MACI implanted

MACI is autologous chondrocyte implantation, simplified2

MACI is less invasive than previous ACIs—may be done through a mini-arthrotomy.

MACI is simplified—does not require supplemental suture fixation.

MACI is reproducible—consistently delivers a controlled, uniform dose of characterized cells to the defect area, regardless of defect size.

See how MACI works

The science behind MACI

MACI vs. microfracture: improvements in pain and function3

A significantly greater proportion of patients treated with MACI experienced clinically meaningful improvements in both pain and function at 2 years when compared to microfracture.3

In a follow-up extension study, improvements in pain and function at Year 2 were maintained with MACI at Year 5.4

Mean patient-reported KOOS scores at year 2 and year 54

Chart of >Mean patient-reported KOOS scores at year 2 and year 5

Baseline KOOS Scores for MACI patients:
37.1 Pain / 15.4 Function

Baseline KOOS Scores for Microfracture patients:
35.2 Pain / 11.9 Function

Legend for chart of >Mean patient-reported KOOS scores at year 2 and year 5

Patient-reported KOOS responder rates at week 104

The responder rate was higher with MACI when compared with microfracture (P=0.016). Response is defined as ≥10-point improvement in both pain and function.3





MACI is a third-generation ACI, offering a simplified way to deliver cells2

MACI has proven results3,4 with over 21 years of clinical experience.5

MACI is FDA approved based on results from the rigorous phase 3 SUMMIT clinical study.3

MACI is the only biologic knee cartilage therapy to gain FDA approval through the Biologics License Application.6

MACI results have been reported in a growing body of literature, including nearly 50 publications and 5 randomized controlled trials.7

MACI manufacture

Manufactured in accordance with quality GMP standards

MACI is aseptically manufactured from a patient’s autologous cells in an FDA licensed facility using only sterile materials.

Manufacturing clean rooms maintain the highest cleanliness standards through automated environmental controls and monitoring.

Each phase of manufacturing is monitored and tested for microbial contamination.

Our scientists and engineers are protected by pre-sterilized gowning materials for the safe production of MACI.

Uniform loading unit

Uniform Loading Unit (ULU™)

A patient’s characterized cells are distributed onto the MACI membrane in a density of 500,000 to 1,000,000 per cm2 using the proprietary Uniform Loading Unit (ULU). Uniform loading allows for the application of a consistent dose of cells to the defect in a less invasive surgical delivery.

Image shown: High Magnification SEM shows chondrocyte attachment to collagen fibers

Every MACI implant undergoes rigorous release testing to confirm:


Verifies a sufficient amount of viable chondrocytes for implantation is available


Uses genetic markers to identify chondrocyte cells


Validating the ability to form a durable repair tissue


Used throughout the process to detect most organisms within 48 hours*

*sterility results are not available at the time of shipping

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References: 1. Pettit RJ, Everhart JS, DiBartola AC, Blackwell RE, Flanigan DC. Time Matters: Knee Cartilage Defect Expansion and High-Grade Lesion Formation while Awaiting Autologous Chondrocyte Implantation. Cartilage. 2021 Dec;13(2_suppl):1802S-1808S. 2. Gooding CR, et al. A Prospective, Randomised Study Comparing Two Techniques of Autologous Chondrocyte Implantation for Osteochondral Defects in the Knee: Periosteum Covered Versus Type I/iii Collagen Covered. Knee. 2006: 13(3): 203-210. 3. Saris D, Price A, Widuchowski W, et al. for the 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;42:1384-1394. 4. Brittberg M, Recker D, Ilgenfritz J, Saris D. 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;46(6):1343-1351. 5. Cherubino P, Grassi FA, Bulgheroni P, Ronga M. Autologous chondrocyte implantation using a bilayer collagen membrane: a preliminary report. J Orthop Surg (Hong Kong). 2003 Jun;11(1):10-5. 6. Gudeman AS, Hinckel BB, Oladeji L, Ray TE, Gersoff W, Farr J, Sherman SL. Evaluation of Commercially Available Knee Cartilage Restoration Techniques Stratified by FDA Approval Pathway. The Am J Sports Med. 2021 Sep 15 (online). 7. Hadley CJ, Shi WJ, Murphy H, Tjoumakaris FP, Salvo JP, Freedman KB. The Clinical Evidence Behind Biologic Therapies Promoted at Annual Orthopaedic Meetings: .A Systematic Review. Arthroscopy. 2019 Jan;35(1):251-259.

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.


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.