For those who have experienced an irreparable injury to the meniscus, or had a total or partial meniscectomy, a meniscus allograft transplantation (MAT) is often preferred to restore the biomechanical functioning of the meniscus.
Although the indications for MAT have not been established yet, it has been indicated with symptomatic patients that have early or mild cases of osteoarthritis, for those older than 50, and for those with an outerbridge of grade II or lower. The short-term and intermediate results have indicated clinical improvements, as well as consistent objective findings. There is a need for long-term observations, in order to evaluate and determine the longevity of these promising results.
The menisci are responsible for transmitting loads across the knee, reducing stress with an increase in contact area throughout the joint, joint lubrication, joint stability, shock absorption, and also nutrition of the chondrocytes. A tear to the meniscus will result in increased stress to the knee joint, and reduce the contact surface between the femur and tibia.
When treating meniscal tears, in most cases a repair is preferred rather than a meniscectomy, and a partial meniscectomy is preferred instead of a complete removal of the meniscus. Unfortunately, with some types of tears to the meniscus, a partial meniscectomy or meniscal repair is not a viable option. With radial repairs that have extended to the joint capsule, or with knees that have severe degenerative changes, a total or partial meniscectomy is unavoidable.
MAT Offers Pain Relief and Improves Function
The meniscus allograft transplantation (MAT) was first introduced in 1989, and has remained controversial while being the subject of many studies. It has been a widely performed procedure to relieve pain and provide functional improvement, and with a variety of methods being utilized, there are no properly established techniques.
While indications for MAT still remain controversial, the prime candidates for this procedure are those older than 20, who have previously had a meniscectomy, do not have joint instability or severe degenerative changes, have localized swelling or pain with the meniscus-deficient area, and have a normal alignment in the lower limb.
A meniscus transplant is known to produce unsatisfactory results with knees that have advanced arthrosis, and is the reason for the procedure being recommended for patients that have grade I and II cartilage damage. However, there are recent studies that report the procedure has resulted in functional and clinical improvements after being performed on patients carefully selected with grade III and grade IV damage to the cartilage, and also combined with other procedures for damaged cartilage.
Along with the condition of the articular cartilage, the stability of the ligament and lower limb alignment is important to consider with a MAT procedure because ligament instability and misalignment can cause early failure with the procedure. In these cases a ligament reconstruction may be necessary, or a concomitant or staged malalignment may need to be performed.
Allograft Sizing important for Procedure
The meniscus allografts are able to be deep frozen or fresh frozen, cryopreserved, freeze-dried or lyophilized, or fresh. Despite having low cell viability, deep frozen or fresh frozen grafts are the most commonly used due to higher success rates, a lower risk of transmitting disease due to a reduction in immunogenicity with histocompatible antigens in the grafts, and its ability to maintain biomechanical properties.
Proper graft sizing is critical with promoting tissue healing and restoring the chondroprotective role in the meniscus. The size is able to be determined by magnetic resonance imaging (MRI), plain radiography, or computed tomography (CT). A meniscus transplant can either be performed with an arthroscopic or open approach, but most commonly the arthroscopic approach is used.
In regard to the method for graft fixation, the fixation with soft tissue along with bone plugs attached to the posterior and anterior horns is found to be more effective than just using the soft tissue fixation for obtaining rigid fixation along with restoring almost normal contact mechanics.
Complications and Benefits of Meniscus Transplant
Some possible complications with a meniscus transplant can be ruptures, extrusion, and graft shrinkage. A graft shrinkage can be common with lyophilize grafts, but with fresh frozen or fresh grafts it is a more rare occurrence. The main goal of a meniscus transplant is to protect the cartilage and its efficacy. Some studies recommend that a transplant be performed as early as possible in order to benefit the chondroprotective role, while other studies show no significant correlation between timing and chondroprotection.
A meniscus transplant is an excellent option for patients that do not suffer from knee instability or malalignment, as well as those who have already had a total or partial meniscectomy. The short-term and mid-term outcomes of a transplant have proven to be successful with improving knee functions and providing pain relief. While there are not any established surgical techniques with a meniscus transplant and the current methods are challenging, the results have been promising and long-term follow up studies need to be conducted to determine its overall success.
Dr. Sumit Dewanjee with FXRX is the top knee surgeon in Arizona. He offers all types of knee procedures including meniscectomy, meniscus repair and meniscal transplants. Dr. Dewanjee is Board Certified and Fellowship Trained, and has received the Patients Choice Award 5 straight years!
Most insurance is accepted at the practice, call (480) 449-3979 today!
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