Exploring MACI Knee Surgery Clinical Trials and Patient Outcomes Skip to content

Exploring MACI Knee Surgery Clinical Trials and Patient Outcomes

Your patients with knee cartilage damage come to you seeking lasting improvements in knee pain and function. As you match them with the most appriopriate treatment, consider the findings of the SUMMIT data trial. It demonstrates how the MACI knee procedure, third generation of autologous chondrocyte implantation, stacks up against microfracture over the long term in the treatment of articular cartilage damage.1

The SUMMIT Trial: MACI vs. Microfracture

In a direct comparison study between microfracture and MACI, the SUMMIT trial randomized and matched patients and evaluated their progress two years after their cartilage procedures and again in a follow up extension study.

At two years after treatment, patients in the MACI knee surgery group produced higher KOOS scale sub-scores over microfracture in terms of improvement in both pain and function of the treated knee. Those improvements were maintained at a five-year check-in.

MACI surgery vs Microfracture improvement in pain and function at two years post op.


In a responder analysis, the proportion of subjects with at least a 10-point improvement in both KOOS pain and function was greater in the MACI group (63/72=87.5%; 95% CI [77.6%, 94.1%]) compared with the microfracture group (49/72=68.1%; 95% CI [56.0%, 78.6%]).2

Patient response rate for MACI procedure vs. microfracture


Patient Case Study with Joseph Czarnecki, MD

Patient ImagingHow does this data connect to real patient experience? We asked Joseph Czarnecki, MD, a Massachusetts-based orthopedic surgeon with more than two decades of experience, to discuss the long-term recovery benefits he has personally seen as a MACI physician. Dr. Czarnecki is affiliated with Massachusetts General Hospital and continues to teach Orthopaedic Residents from the Harvard Combined Orthopaedic Program. He also serves as faculty for the Arthroscopy Association of North America teaching residents.

In a Dr. Czarnecki case study, a 23-year-old female athlete came in with patellofemoral instability and a chondral defect in her knee. After an initial consultation, Dr. Czarnecki discovered she was a former collegiate athlete and current recreational athlete who experienced her first patellar dislocation at 16 years old. Her dislocation was treated with a lateral release, which resulted in her symptoms worsening to the point that she could not use the stairs or work out comfortably.

After a physical exam, Dr. Czarnecki discovered that her patella was unstable and had scarring from her lateral release. Imaging found her trochlea looked fine, but she experienced crepitus and no J sign.

During the knee arthroscopy, extensive damaged and delamination were identified. The patient felt some relief after the arthroscopy. This indicated to the healthcare team that her remaining cartilage was intact.

Dr. Czarnecki and his team performed the follow up MACI knee procedure and reimplanted the MPFL with allograft.

MACI Surgery

Following the MACI surgery, the patient followed her personalized rehabilitation program diligently. Her pain level was 0-2/10, and effusion trace to none. She had minimal crepitus and a stable patella and returned to level ground jogging at nine months.

Individual results may vary.


Please see below for full indication and ISI.


1. 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.

2. 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.

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MACI repairs knee cartilage using your patient’s own chondrocytes

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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.