Cartilage Transplantation (MACI)

Introduction to Cartilage Transplantation

Cartilage damage, often caused by sports injuries, arthritis, or accidents, can lead to chronic pain and mobility issues. Unlike other tissues, cartilage has limited self-healing ability, making advanced treatments like cartilage transplantation essential. One of the most innovative procedures today is MACI (Matrix-Induced Autologous Chondrocyte Implantation), a next-generation technique that helps restore damaged cartilage using the patient’s own cells. This guide explores how MACI works, who it benefits, and what to expect from recovery.

What is MACI (Matrix-Induced Autologous Chondrocyte Implantation)?

MACI is a cutting-edge, FDA-approved cartilage repair procedure designed to treat knee cartilage defects. Unlike traditional methods, MACI uses a patient’s own chondrocytes (cartilage cells), which are harvested, cultured in a lab, and implanted onto a biodegradable collagen membrane. This membrane is then surgically placed over the damaged area, promoting natural cartilage regeneration. Because it uses the patient’s cells, MACI reduces rejection risks and improves long-term joint function. It’s particularly effective for active individuals with focal cartilage injuries who want to avoid joint replacement.

How Does MACI Work? – The Step-by-Step Procedure

The MACI procedure involves two main stages:

Arthroscopic Biopsy: A small sample of healthy cartilage is taken from a non-weight-bearing area of the knee.
Lab Culturing: The harvested cells are sent to a lab, where they multiply over 4-6 weeks on a collagen membrane.
Implantation Surgery: The cultured cartilage membrane is trimmed to fit the defect and secured with fibrin glue or stitches.

The entire process is minimally invasive compared to older techniques like ACI (Autologous Chondrocyte Implantation), reducing recovery time.

Who is a Candidate for MACI?

MACI is ideal for patients with:

Localized cartilage defects (2–10 cm²) in the knee.
Active individuals under 55 seeking to delay joint replacement.
Failed prior treatments (e.g., microfracture, OATS).

However, it’s not recommended for those with advanced osteoarthritis, infections, or widespread cartilage loss. A thorough evaluation by an orthopedic surgeon is necessary to determine eligibility.

Benefits of MACI Over Traditional Cartilage Repair Methods

MACI offers several advantages:

Natural Regrowth: Uses the patient’s own cells for better integration.
Minimally Invasive: Requires only one open surgery (unlike two-stage ACI).
Faster Recovery: Shorter rehab than older techniques like microfracture.
Durable Results: Studies show long-term improvement in pain and function.

Compared to microfracture (which creates scar tissue), MACI produces hyaline-like cartilage, closely resembling natural tissue.

Recovery Process & Post-Operative Care

Recovery after MACI is gradual and requires strict adherence to rehab:

Weeks 1–6: Non-weight-bearing with crutches; focus on reducing swelling.
Weeks 6–12: Partial weight-bearing; physical therapy begins.
Months 3–6: Full weight-bearing; strength and mobility exercises.
6+ Months: Return to sports (if cleared by the surgeon).

Following post-op instructions is crucial to protect the new cartilage and ensure optimal healing.

Potential Risks and Complications

While MACI is generally safe, possible risks include:

Graft Failure: Rare but may require revision surgery.
Joint Stiffness: Managed with physical therapy.
Infection: Minimized with sterile techniques.

Choosing an experienced surgeon significantly reduces these risks. Discuss all concerns during your consultation.

Success Rates & Long-Term Outcomes

Clinical studies report:

80–90% success rate in pain reduction and functional improvement.
Durable results lasting 10+ years in suitable candidates.

Factors like age, defect size, and adherence to rehab influence outcomes. MACI is a long-term solution for cartilage defects when performed correctly.

Frequently Asked Questions (FAQs) About MACI

1. Is MACI painful?

Post-surgery discomfort is managed with medications. Most patients report less pain than traditional ACI.

2. How long until I can walk normally?

Most patients walk without crutches by 6–8 weeks but full recovery takes 6–12 months.

3. Does insurance cover MACI?

Many insurers cover MACI for eligible patients, but pre-authorization is often required.

Cartilage Transplantation (MACI – Matrix-Induced ACI): A Complete Guide