Focus of the Report: This report focuses on matrix-induced autologous chondrocyte implantation (MACI) for the treatment of patients with chondral defects of the knee.

Technology Description: MACI is a multi-stage procedure that involves 2 surgeries. During an initial arthroscopic surgery, a biopsy of healthy cartilage is obtained. The cartilage sample is then sent to a laboratory, where chondrocytes are isolated from the biopsy and expanded in vitro for a period of weeks. After an appropriate concentration of chondrocytes has been achieved, the chondrocytes are seeded onto a 3-dimensional matrix. Then, during a second surgical procedure (with arthroscopic or mini-arthrotomy approach), surgeons conduct a debridement of the damaged cartilage site and glue the seeded matrix to fill the entirety of the defect. Postoperatively, patients then undergo a progressively intensive regimen of physical rehabilitation and over a period of months, the implanted chondrocytes slowly replicate and refill the defect site with healthy hyaline cartilage.

Controversy: For patients with chondral defects of the knee that remain symptomatic despite optimal palliative treatment, microfracture (MFX) is considered the first-line surgical treatment. Although MFX has established clinical efficacy and safety for the treatment of knee cartilage defects, MFX risks damage to the subchondral structure of the knee and replaces the sites of damaged hyaline cartilage with inferior fibrocartilage, which sometimes is not sufficient to cushion the shear forces that the knee regularly endures. MACI is a surgical alternative to MFX that may achieve superior clinical results since the defect site is replaced with autologous hyaline cartilage. However, the cost and intensiveness of the 2 MACI surgeries and the 6-month to 1-year long rehabilitation involves a large degree of financial and personal commitment. Additionally, the patient selection criteria for MACI, and the comparative effectiveness and safety to other restorative surgical alternatives, are relatively unknown.

Key Questions:

  • Is MACI effective for treatment of knee cartilage defects?

  • How does MACI compare with other knee cartilage repair surgeries?

  • Is MACI safe?

  • Have definitive patient selection criteria been identified for MACI?

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