There are very specific criteria that need to exist for MAT to be a reasonable choice. Most importantly:

• Symptomatic loss of all or most of the meniscus

• Healthy surrounding cartilage

• Good alignment of the leg

• Good stability of the knee ligaments

Generally MAT is a good surgery for those who fit the criteria. MAT is a technically complex surgery that should be performed by surgeons with considerable experience in this field. Here is an overview of the current knowlege we have around this topic

Overview of Meniscus Allograft Transplant (MAT)

Meniscus allograft transplantation (MAT) has evolved significantly as a treatment option for symptomatic patients who have lost a significant portion of their meniscus due to injury or previous surgery. Here's an up-to-date overview based on current literature and practice:

Indications:

• Symptomatic Meniscal Deficiency: Primarily for patients younger than 50 with pain localized to the compartment where the meniscus is missing, but without advanced osteoarthritis (OA).

• Post-Meniscectomy Syndrome: For those experiencing pain, swelling, and instability after a total or subtotal meniscectomy (removal of the meniscus).

• Concomitant Procedures: Often performed alongside correction of knee alignment, ligament reconstruction, or articular cartilage repair to ensure optimal outcomes.

Techniques:

• Surgical Methods:

  • Bone Plug vs. Soft Tissue Fixation: Both techniques are used, with bone plug fixation showing potentially better biomechanical outcomes, though soft tissue fixation is also effective with fewer complications in some studies.

  • Arthroscopic vs. Open Surgery: There's a trend towards arthroscopic techniques due to less invasiveness and potentially quicker recovery.

• Graft Preparation:

  • Fresh-Frozen vs. Cryopreserved: Fresh-frozen allografts are more commonly used for their biomechanical properties similar to native meniscus, although cryopreserved options are also viable with high cell death noted.

  • Sizing: Accurate sizing is critical for success, often using radiographic or MRI measurements for matching.

Outcomes:

• How long will it last:

  • Approximately 73.5% last 10 years and 60.3% 15 years, suggesting a decrease over time but still providing significant symptom relief for many patients.

  • Lateral meniscus transplants generally have higher survival rates compared to medial ones.

• Clinical Benefits:

  • Significant improvement in pain scores and knee function, with about 90% of patients reporting they would undergo the procedure again.

  • Possible chondroprotective effect (strategies and substances that protect and smooth cartilage), although long-term evidence on delaying OA is still debated.

• Complications:

  • Reoperation rates are around 32%, with the most common issue being meniscal allograft tears.

  • Other complications include graft extrusion, failure, and progression of joint pathology.

Challenges and Considerations:

• Patient Selection: Critical for success; patients with advanced arthritis or significant malalignment might not benefit as much.

• Graft Availability: The need for size and compartment-specific grafts can sometimes delay or complicate the procedure.

• Long-term Efficacy: While short to medium-term outcomes are promising, the long-term chondroprotective effect remains under scrutiny.

• Cost and Accessibility: MAT is costly and not universally available, leading to disparities in treatment access globally.

Future Directions:

• Research Focus: Ongoing studies aim to better understand the long-term effects on OA progression, improve graft survival, and refine surgical techniques.

• Biological Augmentation: Techniques like using PRP or stem cells during surgery to enhance healing and integration are being explored.

• Segmental Transplants: For cases where only part of the meniscus is damaged, segmental transplants are being investigated as an option to preserve more native tissue.

In summary, MAT is becoming a well-established procedure for selected patients with symptomatic meniscal loss, offering good functional outcomes and pain relief, though it comes with its set of challenges and areas for further research.