The goal of meniscal surgery is to maintain the cartilage function. Preserving meniscal functionality is a top priority but nearly 90% of tears cannot be repaired so the torn portion is surgically removed. Although this falls into the category of only a partial meniscectomy, the outcome is still the same and from a functional perspective, it results in the same outcome as a total meniscectomy. Arthritis often results over time. Meniscal transplantation involves the use of a size-matched cadaver donor meniscus that is transplanted into the site of the original meniscus with the intent of regaining meniscal function.
Arthroscopic Chondroplasty & Microfracture
For patients who have had the meniscus removed, the surgeon may offer an innovative solution called a meniscal transplant. It is important to remember that even though only a part of the meniscus was removed, at times the effect to the knee from a biomechanical standpoint is the same as a total menisectomy. The indications for transplant need to be assessed by your cartilage surgeon. Unlike other forms of tissue transplantation, this procedure does not require patients to be on medications to prevent rejection. Intermediate term follow-up studies in the literature are encouraging.
The articular cartilage that covers the bones at the joint experiences a constant wear and tear. The cells of the articular cartilage, called the chondrocytes, make the matrix or this external covering of the bones. Chondrocytes do not replicate, cannot repair themselves when injured, and also decrease in number as the aging process progresses. The damaged or lost chondrocytes then fail to support the articular cartilage regeneration process and articular cartilage defects occur. Articular restoration procedures either enable the surgeon to stimulate a healing response or replace the worn tissue completely.
Osteochondral Autograft (OATS)
This technique is analogous to a hair-plug transfer. The surgeon removes a small section of the patient’s own cartilage along with the underlying bone plug. This is obtained from an area which does not participate in high loading.
This bone and cartilage (hence osteo—chondral) local graft is then transferred to the defect where a receiving hole has been prepared. Obviously, there is a limit to the amount of tissue available for “harvesting.” The typical site of harvest is at the margin of the femoral trochlea where the patella glides—if that area is involved with damage then this technique may not be possible. The size of the defect treatable with this method is usually between 1 and 2 square cm or slightly larger than a thumbnail.
Autologous Cartilage Cell Implantation
For articular cartilage defects greater than 2cm2, one of the more advanced techniques for cartilage regeneration is ACI (Autologous Chondrocyte Implantation).
The first stage may be performed when initially assessing the joint arthroscopically. A small amount of the patient’s own articular cartilage is harvested. Through cell culturing techniques, the cell number is increased from a few hundred thousand to over 10 million cells. These autologous (your own) cultured cells are then implanted in the knee in a second surgical procedure to repair and resurface areas of cartilage loss. The cells (the marshmallows) represent only 1-5% of the volume of the matrix (jello). These cells must synthesize (create) matrix over several months to reestablish the articular surface.
Ligaments connect bones and stabilize their position. Loss of ligament function results in instability. The instability causes multiple problems including loss of functionality as well as an abnormal stress load on the cartilage, furthering the damage. Ligaments that do not heal may require reconstruction. The most recognized sports-related ligament reconstruction is anterior cruciate ligament reconstruction (ACL reconstruction) to prevent lateral direction change knee instability. The goal for the surgical intervention is always to reproduce the natural ligament function to the extent possible.