The meniscus, a C-shaped cartilage in the knee joint has several important functions such as providing stability and nutrition to the knee joint, shock absorption and protection of the articular cartilage. The meniscus may tear due to injury or trauma and needs to be repaired. The repair is essential in order to preserve the properties and the functions of the knee. Allograft meniscus transplantation is one of the surgical techniques to repair the torn meniscus. Technical advancements in the graft preparation and sterilization have improved viability of the graft and revascularization property as well. The first step in graft procurement is donor screening and selection. A stringent protocol is followed so that disease-free grafts are obtained. The graft tissue will be preserved using either cryopreservation or fresh-frozen method.
Allograft meniscus transplantation is indicated in patients with pain because of absent meniscus (prior meniscectomy). It also delays the onset of osteoarthritis. Allograft repair cannot be performed if the patient is obese and has advanced inflammatory arthritis, synovial disease, previous knee infections, immunodeficiency, and systemic metabolic diseases.
Allograft sizing
The exact size of the absent meniscus is estimated with the help of plain radiographs.
Surgical technique
After administration of general anesthesia, an examination is performed to make sure the ligaments are stable. Then a diagnostic arthroscopy will be done to rule out chondral injuries in the knee compartment involved. Debridement of the residual meniscal tissue is done to stimulate a healing response.
Allograft placement is done arthroscopically. The two techniques that can be used to anchor a meniscal allograft are bone bridge and bone plugs. Both of these techniques require the meniscus to be attached to the posterior and anterior horns. The bone bridge technique is used for medial and lateral meniscus transplants and it fixes the distance between the anterior and posterior rigidly. The bone plug technique can be used only for medial meniscus transplants and it allows for adjustments to match the variable position of the anterior horn. Another technique called bridge-in-slot technique is more efficient and it maintains the natural anatomy of the meniscus. It can be performed in skeletally immature patients.
After allograft insertion is complete, a final arthroscopic examination is done to check for proper placement and size of the graft. Then the graft is secured by placing non-absorbable mattress sutures on the meniscus. Alternatively, all-inside meniscal repair devices may be used to secure the meniscus.
Complications
Complications after allograft repair are rare but may include incomplete healing, infection, arthrofibrosis, injury to nerves and blood vessels.