AANA Lab Course 910 - Patellofemoral Joint Preservation-MACI-Dr. Jack Farr II, M.D.

MACI-Dr. Jack Farr II, M.D.

Pdf Summary

Matrix-Assisted Autologous Chondrocyte Implantation (MACI) is an advanced cell-based therapy used to repair symptomatic, full-thickness cartilage defects in the knee, including those involving the patellofemoral joint. The procedure involves isolating chondrocytes from a cartilage biopsy, expanding these cells in vitro for approximately three weeks, then seeding them onto a biodegradable collagen membrane that serves as a scaffold. This cell-seeded membrane is implanted into the cartilage defect site via a minimally invasive mini-arthrotomy, secured with fibrin glue. The membrane supports cartilage regeneration as it is gradually resorbed over about six months.<br /><br />Historically, MACI evolved from first-generation autologous chondrocyte implantation (ACI) techniques first reported in the 1990s. It received FDA approval for knee cartilage repair based on clinical trials demonstrating safety, efficacy, and long-term durability compared to microfracture treatments.<br /><br />Rehabilitation is structured over several phases spanning from implantation to full tissue maturation over 2-3 years, focusing on protecting the implant, promoting cellular proliferation, remodeling, and gradual restoration of cartilage function.<br /><br />A systematic review and meta-analysis of 59 studies (1,274 patients receiving cell-based therapies for patellofemoral lesions) showed that MACI yields significant improvements in patient-reported outcomes (PROs), including pain and function. Outcomes appear more favorable for trochlear lesions compared to patellar ones, with lesion size (>10 cm²) and combined risk factors such as female sex and need for realignment surgeries associated with poorer results. Age and etiology have not been shown to significantly influence outcomes.<br /><br />Complications and failure rates are generally low but can include minor or major adverse events. Several studies confirm the sustained improvement in knee function over 2-10 years after MACI for patellofemoral cartilage lesions, with recommended patient selection and careful postoperative management essential to optimizing results.<br /><br />In summary, MACI is a validated biological treatment option for complex patellofemoral cartilage defects in adults under 55 years, providing durable cartilage repair through minimally invasive cell-based implantation and scaffold technology combined with structured rehabilitation protocols.

Keywords

Matrix-Assisted Autologous Chondrocyte Implantation

MACI

cartilage repair

knee cartilage defects

patellofemoral joint

chondrocyte implantation

biodegradable collagen membrane

cell-based therapy

rehabilitation protocols

patient-reported outcomes