In this study from Italy, orthopedic surgeons transplanted donor menisci (plural for meniscus) in the knee of 32 patients and then reported the results over the next three years. Allografts (donor menisci) were used. And they used a specific technique of suturing the graft cartilage that was different from other studies.
Instead of taking plugs of bone and using them like pegs to hold the donor graft cartilage in place, they used sutures. But that wasn’t what made their surgical approach so unique. They also secured or “fixed” the graft to the anterior capsule (anterior means front, capsule refers to the cartilage and connective tissue that forms a cap around the knee).
In other studies, surgeons either used bone plugs or sutured the graft to the anatomic or original insertion point on the tibia (lower leg bone). But the authors say their technique is faster and easier. And now their results show the outcomes are just as good as other methods of graft fixation. They suggest that the best way to get optimal results with meniscal transplantation is to select the correct graft size for each patient, place the graft anatomically, and secure it in a way that promotes biologic healing.
By fixing the sutures to the front of the tibial plateau, they were also able to make a single tunnel through the tibial bone using an arthroscope. With this approach, they could also complete all suturing inside the joint, referred to as an all-inside method of fixation. There is less disruption to the soft tissues of the knee with this method, which could also promote faster healing and recovery.
But how do the results match up with other techniques (e.g., using bone plugs instead of sutures, placement of the sutures in the anatomic location)? Using pain, knee motion, and function as the main measures of results, they found significant improvements in 94 per cent of the patients in their group. There was reduced pain and improved knee function still present three years after the procedure.
Magnetic resonance imaging also showed this surgical method offered a protective effect to the bone underneath the transplanted cartilage. This is referred to as a chondroprotective effect. The only concern was for the graft extrusion observed on MRIs in two-thirds of the group.
Extrusion of the graft refers to pushing of a part of the graft material out of the knee joint cavity. This extrusion was more common in grafts on the lateral side of the knee (the side away from the other knee). There did not appear to be any effect of this extrusion on patient pain or function — at least not in the short-term. Long-term studies may show a different result.
No one knows exactly why graft extrusion occurs. But it is commonly reported in all studies involving meniscal transplantations. Experts suggest a variety of possible reasons for this problem. The fact that the lateral side pushes out more often than the medial side (side closest to the other knee) suggests factors involving biomechanics and load distribution.
But it could be there are effects of surgical technique from putting too much tension on the sutures, using a graft that’s too large for the space (called “overstuffing”), or when the sutures do not reattach the graft at the anatomical location (where the meniscus normally inserts into the bone).
Given the short-term success of this surgical technique, the authors suggest a longer study to follow these patients 10 years or more. A longer period of time would help show whether or not there is a true chondroprotective effect of meniscal allografts. Future studies could also compare allografts implanted this way versus implants secured with bone plugs. Comparing different types of MRIs (e.g., taken while lying down versus standing on one leg or both legs) might also offer some additional information.