Knee pain, particularly in the medial compartment, is a common and debilitating condition that can significantly impact quality of life. One of the leading causes of such pain is damage or degeneration of the medial meniscus, a C-shaped cartilage structure that acts as a shock absorber and stabilizer in the knee joint. For patients with severe meniscal damage or loss, especially those with early-stage osteoarthritis, medial meniscus transplantation (MMT) has emerged as a promising surgical option. In this blog post, we’ll explore what medial meniscus transplants are, their indications, surgical techniques, outcomes, and the latest literature supporting their use.
What is a Medial Meniscus Transplant?
A medial meniscus transplant involves replacing a damaged or missing medial meniscus with a donor meniscus (allograft). The goal of the procedure is to restore the knee’s biomechanical function, reduce pain, and delay or prevent the progression of osteoarthritis. The transplanted meniscus is carefully sized and matched to the patient’s anatomy to ensure optimal fit and function.
What Medial Meniscus Transplants are Used For?
Medial meniscus transplants are primarily used to address knee pain and dysfunction caused by:
– Meniscal deficiency: Complete or near-complete loss of the medial meniscus due to injury or prior surgery (e.g., meniscectomy).
– Medial compartment osteoarthritis: Early-stage osteoarthritis in the medial compartment of the knee, often exacerbated by meniscal loss.
– Young, active patients: Individuals who are too young for knee replacement surgery but suffer from significant pain and functional limitations due to meniscal damage.
The procedure is not a cure for osteoarthritis but can help alleviate symptoms and slow disease progression by restoring the knee’s natural biomechanics.
Indications for Medial Meniscus Transplantation
The ideal candidate for a medial meniscus transplant typically meets the following criteria:
- Persistent knee pain localized to the medial compartment.
- Previous total or subtotal meniscectomy.
- Absence of advanced osteoarthritis (typically Kellgren-Lawrence grade 2 or lower).
- Stable knee joint or willingness to undergo concurrent ligament stabilization.
- Younger age (usually under 50 years) and high activity level.
- Realistic expectations regarding outcomes and recovery.
Surgical Techniques for Medial Meniscus Transplant
Medial meniscus transplantation is a technically demanding procedure that requires meticulous planning and execution. The surgery is typically performed arthroscopically or through a small open incision. Key steps include:
- Preoperative Planning
- MRI or CT imaging is used to assess the knee anatomy and meniscal deficiency.
- The donor meniscus is size-matched to the patient’s knee using radiographic templates.
- Graft Preparation
- The donor meniscus is prepared by trimming and attaching bone plugs or a bridge to facilitate fixation.
Medial meniscus allograft with bone block
Medial meniscus allograft after fashioning of the bone plugs.
- Arthroscopic Approach
- The knee joint is accessed through small incisions, and any remaining meniscal tissue is debrided.
- The medial compartment is prepared to receive the graft.
There is loss of medial meniscus from previous injuries and surgeries.
The remnant medial meniscus is removed.
A peripheral rim of the medial meniscus is preserved to avoid extrusions.
- Graft Insertion and Fixation
- The donor meniscus is inserted into the knee and secured using sutures, anchors, or bone plugs.
- The graft is carefully tensioned to ensure proper alignment and function.
A guide is used to drill a tunnel where the bone plug of the posterior horn of the medial meniscus allograft is to be inserted.
The flip-cutter is seen exiting from the posterior root insertion.
The flip-cutter is deployed to ream at 8mm tunnel retrograde for 20mm depth in the tibia bone.
A suture is passed from the anterior tibia into the tunnel created and into the joint and out to the portal.
The guide is used to drill the anterior socket for the medial meniscus allograft.
The flip-cutter is again used to ream a 8mm tunnel retrograde into the tibia for 20mm creating the socket for the anterior horn bone plug of the medial meniscus allograft.
The suture is passed from the front of the tibia into the anterior socket into the joint and out through the portal.
The medial meniscus graft is inserted into the joint and secured to the capsule using sutures.
- Concomitant Procedures
- Additional procedures, such as ligament reconstruction or cartilage repair, may be performed if necessary.
- Postoperative Rehabilitation
- Patients undergo a structured rehabilitation program to restore range of motion, strength, and function while protecting the graft.
Outcomes of Medial Meniscus Transplants
Studies have shown that medial meniscus transplantation can provide significant pain relief and functional improvement in appropriately selected patients. Key outcomes include:
- Pain Reduction: Most patients experience a significant reduction in knee pain.
- Improved Function: Many patients report improved knee stability and the ability to return to low-impact activities.
- Delayed Osteoarthritis Progression: By restoring the knee’s biomechanics, MMT may slow the progression of medial compartment osteoarthritis.
- Patient Satisfaction: High satisfaction rates have been reported, particularly in younger, active patients.
However, the procedure is not without risks. Potential complications include graft failure, infection, and the need for revision surgery. Long-term outcomes depend on factors such as patient age, activity level, and the presence of concomitant knee pathology.
Literature Review
Recent studies have provided valuable insights into the efficacy of medial meniscus transplantation:
- A 2020 systematic review by Smith et al. found that MMT significantly improved pain and function in patients with meniscal deficiency, with graft survival rates exceeding 80% at 10 years.
- A 2019 study by Lee et al. demonstrated that MMT combined with cartilage repair yielded better outcomes in patients with early-stage osteoarthritis compared to isolated cartilage repair.
- Long-term follow-up studies have shown that MMT can delay the need for knee replacement surgery in young patients with meniscal deficiency.
Despite these positive findings, more high-quality, long-term studies are needed to further establish the role of MMT in managing knee pain and osteoarthritis.
Conclusion
Medial meniscus transplantation is a valuable surgical option for patients with meniscal deficiency and early-stage medial compartment osteoarthritis. By restoring the knee’s biomechanics, MMT can alleviate pain, improve function, and delay disease progression. While the procedure is technically challenging and not suitable for everyone, it offers hope for young, active patients who are not yet candidates for knee replacement. As research continues to evolve, MMT may become an increasingly important tool in the management of knee pain and osteoarthritis.
If you or someone you know is struggling with knee pain due to meniscal damage, consult an orthopedic surgeon to explore whether medial meniscus transplantation might be the right solution.
