Meniscus Implants, Meniscus Replacement, and Meniscus Transplants: Artificial Meniscus, Follow-up Care, and Specialists

Approximately 350,000 people in Europe sustain an acute meniscus injury each year. The cause of most structural meniscus damage is trauma to the knee resulting from sports and recreational activities.

Such damage to the meniscus constitutes a serious defect and must be treated. Otherwise, in the advanced stages of the injury, progressive damage to the cartilage in the knee joint may occur, which in the long term increases the risk of developing osteoarthritis.

If the meniscus is severely worn or completely eroded, the remaining cartilage tissue can no longer be repaired. In such cases, orthopedic specialists assess whether a replacement or reconstruction is necessary. Sometimes, the removed tissue is examined histologically to determine the exact extent of the damage.

If the meniscus is worn down and literally frayed, the remaining tissue structure can no longer be repaired.

In this situation, replacement of the removed sections of the meniscus is recommended. Possible options for replacing the damaged meniscus include

• the use of the patient’s own tissue,
• the use of synthetic materials, as well as
• the latest trends in bioresorbable scaffolds.

A relatively new procedure involves the use of collagen meniscus implants (CMI). This biological implant serves as a resorbable scaffold for the body’s own cartilage tissue to grow into. Resorbable means that the body can break it down on its own.

The collagen meniscus consists of highly purified collagen and has a sponge-like structure. In this way, medicine harnesses the body’s ability to regenerate tissue. The shape of the alloplastic meniscus is modeled after the human medial and lateral menisci.

The alloplastic meniscus is implanted during an arthroscopic procedure, that is, as part of a minor surgical intervention. The surgeon sutures the implant into the area where the meniscus tissue was removed. The porous structure of the implant serves as a guide for the ingrowth of new tissue.

As a result, new cells from the patient’s own body colonize the artificial meniscus. They form new meniscus-like tissue. After about one year, the alloplastic meniscus implant has largely been resorbed and replaced by the patient’s own tissue structure.

Clinical studies from the U.S. and Europe demonstrate that the meniscus implant supports the growth of new tissue structures. Treatment with the collagen meniscus implant significantly reduces pain. With the meniscus implant, patients are able to return to a level of activity comparable to that they had before the meniscus tear.

To date, more than 1,400 patients worldwide have undergone successful surgery with the meniscus implant. These were primarily people who placed great importance on regaining their ability to participate in sports.

However, for this regenerative method to be successful, the patient must strictly follow their doctors’ instructions. This also includes having the necessary patience. It takes time for new tissue cells to grow into the meniscus implant.

The follow-up period after the implantation of a synthetic meniscus lasts six months.

Initially, the patient gradually and steadily increases the load and range of motion. After two months, the patient can usually bear full weight on the operated knee again.

At this point, the patient begins rehabilitation training to resume their usual athletic activities. After approximately six months, they can fully resume their usual athletic activities.

An MRI after two years is recommended to assess the success of the procedure.

The implantation of a collagen meniscus is currently the only method for the biological regeneration of lost or injured meniscus tissue and the restoration of the meniscus’s original function.

From a medical perspective, the prerequisites for the success of this meniscus implant surgery and for the implant to integrate successfully are:

• The existing meniscus damage or meniscus tear cannot be treated by any other means.
• A largely intact meniscus rim and stable meniscus ends must be present for suturing.
• The size of the injury must account for at least 25 percent of the meniscus tissue.
• There should be no or only minimal damage to the articular cartilage, and no misalignment of the leg axis.
• There is no capsular or ligament instability.

Overall, the published literature does not allow for any conclusions regarding long-term outcomes

of alloplastic meniscus implants. However, the findings from very small groups are encouraging. It may therefore be worthwhile for affected patients to contact a center experienced with this method.