Meniscus Allograft Transplant: All About MAT

Meniscus Allograft Transplant (MAT) Surgery: 

Who is a Candidate? 

The meniscus is a C-shaped cushion of cartilage in the knee joint. When people talk about "torn cartilage" in the knee, they are usually referring to a torn meniscus. 

If the meniscus is so badly damaged that it cannot be repaired, it may need to be removed or trimmed out. This is called a partial meniscectomy and is often effective in relieving the pain of a meniscus tear. 

When the meniscus is largely gone, however, persistent knee pain and or osteoarthritis can develop.  For many older patients with this condition, a total or partial joint replacement might be the right option. But active people who are younger than 40 may be eligible for an alternative treatment: meniscal transplant surgery. 

A meniscal transplant replaces the damaged meniscus with donor tissue matched for size. 

Meniscal transplants are not right for everyone. If you already have arthritis in your knee, a meniscal transplant may not help you. For a select group of people, however, meniscal transplants can offer significant pain relief. 

Meniscus Transplant Rehab 

Immobilization. You will need to wear a knee brace and use crutches for the first 6 weeks after surgery. This gives the transplanted tissue time to become firmly attached to the bone. Range of motion is typically initiated as soon as possible after the procedure. 

Physical therapy. Once the initial pain and swelling have settled down, physical therapy can begin.  Physical therapy initially focuses on pain management, muscle reactivation, and motion. As healing progresses, strengthening exercises will gradually be added to your program. 

Return to daily activities. Most patients are not able to return to work for at least 2 weeks after surgery. Patients with active or labor-intensive jobs may require 3 to 4 months of rehabilitation before they return to work. Full release for sports activity is typically given 9 to 12 months after surgery.

What are the contraindications to MAT?

• Asymptomatic patients
• Severe osteoarthritis
• Uncorrectable malalignment or instability
• Irreparable chondral damage
• Active infection
• Inflammatory arthropathy

What else should I know?

Donor allografts are size-matched to the recipient using x-rays or magnetic resonance imaging measurements. To date, no particular surgical technique has demonstrated superiority. Therefore, there are several used approaches (mini-open or arthroscopic), horns-fixation techniques (soft-tissue, bone-plugs, or bone-bridge), and peripheral suture techniques (inside-out or all-inside).

Ipsilateral malalignment, instability, and/or chondral defects should be corrected or repaired if MAT is being performed.

MAT survival rates are estimated at 73.5% at 10 years and 60.3% at 15 years.

Mean time-to-failure is ∼8.2 and ∼7.6 years for a medial and lateral meniscus transplant, respectively.

Significant improvement in patient-reported outcomes is expected following MAT, and 90% of patients will attest they will undergo the procedure again.