Meniscal Transplantation
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"meniscal transplantation" OR "meniscus transplantation"
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Here is a comprehensive overview of Meniscal Transplantation based on Miller's Review of Orthopaedics (9th Edition):
Meniscal Allograft Transplantation (MAT)
Overview
Meniscal transplantation is controversial. All nonoperative management modalities should be exhausted before it is considered. The primary goal is pain relief — chondroprotection has not yet been definitively demonstrated clinically. Most available studies have only short-term to 5-year follow-up data.
Indications
| Criterion | Detail |
|---|---|
| Prior meniscectomy | Total or near-total meniscectomy, especially the lateral meniscus |
| Pain | In the involved compartment |
| BMI | < 30 |
| Age | Younger than 50 years |
| Chondral status | Addressable full-thickness chondral lesions (not diffuse) |
| Alignment | Normal mechanical axis |
| Ligamentous stability | Knee must be ligamentously stable |
Any ligamentous deficiency or limb malalignment must be corrected prior to or concurrently with transplantation to improve success rates.
Contraindications
- Diffuse Grade III/IV chondral changes
- Kissing lesions (opposing chondral defects on femur and tibia)
- Advanced age
- Inflammatory arthritis
- Synovial disease
- Increased BMI
- Uncorrected mechanical axis deviation toward the affected compartment
- Significant osteoarthritis
Graft Sizing
Accurate sizing is critical — the graft must be within 5% of the native meniscus size:
- Sizing is typically performed using radiographs, but MRI is also acceptable
- Undersized graft → poor joint congruity + increased load transmission
- Oversized graft → meniscal extrusion + impaired compressive load transmission
Surgical Techniques
Two main implantation approaches:
- Individual bone plugs — for the anterior and posterior horns
- Bone bridge technique — particularly used for lateral meniscal transplantation
Outcomes & Biology
- Pain relief is the most consistent and predictable benefit
- Chondroprotective effect has not been clinically demonstrated
- Allograft tissue frequently remains hypocellular or acellular, particularly at the core (incomplete cellular repopulation/revascularization)
- The most common complication is meniscal tear of the allograft
Collagen Meniscal Implant (CMI)
A biological scaffold alternative for irreparable medial meniscal tears:
- Promotes new meniscus-like matrix formation
- Shows promising early results compared to partial meniscectomy
- Long-term data, especially from independent sources, is lacking
Key High-Yield Points
- The lateral meniscus is the more common indication (lateral meniscectomy causes greater biomechanical disruption)
- Partial meniscectomy increases peak stresses in the affected compartment — a key driver of the need for transplantation
- Concomitant procedures (ACL reconstruction, osteotomy) must address instability and malalignment
Recent Evidence
Two recent systematic reviews (2024–2026) highlight important clinical insights:
- Wang et al. (2024) (Arthroscopy) — Concomitant treatment of high-grade cartilage lesions mitigates the risk of meniscal allograft transplant failure. [PMID: 38008388]
- Lin et al. (2026) (Am J Sports Med) — Characterizes the rate of conversion to total knee arthroplasty (TKA) after meniscal allograft transplantation. [PMID: 41476405]
These reinforce the textbook teaching: careful patient selection and addressing concomitant pathology are critical to outcomes.
— Miller's Review of Orthopaedics, 9th Edition, p. 349–350
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