Surgical Advances

A Common Problem

Damage to the cartilage of the knee through injury or “wear and tear” is one of the most common yet difficult problems seen by orthopaedists today. The gradual deterioration of the knee joint, known as osteoarthritis, affects millions of individuals each year. If you suffer from this problem and are over the age of 60, a total knee replacement provides dramatic and reliable relief from pain and is the best treatment. However, if you are younger, total knee replacement is not the best option. Before deciding the proper treatment, we have to thoroughly understand what is exactly injured and wrong with your knee.

There are many causes of osteoarthritis and treatment depends on a multitude of factors, including the condition of your ligaments, menisci, articular cartilage, and the alignment of your leg. Research has shown that the success rate of cartilage procedures depends on the knee being stable and in correct alignment. Therefore, in many knees, cartilage regeneration or restoration procedures are done along with other procedures (such as an osteotomy or ligament reconstruction) to try to correct all of the problems present.

What is Cartilage?

Actually the word cartilage is a general term which describes different structures of the knee. While the composition of these structures is similar, they have different functions or jobs in the knee:

The meniscus acts as a cushion and stabilizing platform between the femur (thigh bone) and tibia (shin bone). There are two menisci in the knee – a medial (or inside) meniscus and a lateral (or outside) meniscus. The menisci are commonly damaged through twisting injuries. Fortunately, some meniscal tears heal on their own and never require surgery. However, at least one-half of injured menisci do not heal and cause pain, locking, and catching. Many surgeons will remove the damaged sections of the menisci to relieve these symptoms. If too much tissue is removed, the meniscus loses its ability to act as the cushion between the femur and tibia, and damage to the articular cartilage begins.

The articular cartilage, also known as the joint lining, is a protective layer of tissue located on the ends of the bones which come together in the knee joint. These bones are the femur (thigh bone), tibia (shin bone), and patella (kneecap). Articular cartilage can be damaged through an injury or gradually deteriorate over time from a variety of factors. When the articular cartilage is damaged or injured, it usually goes through a staged process of softening, flaking, fragmenting, and finally complete loss where the underlying subchondral bone is exposed. This process is commonly known as osteoarthritis. Damaged or injured articular cartilage has a very limited ability to heal itself. Therefore, once the process of osteoarthritis starts, there is little that the body can do to stop the deterioration.

To complicate matters even further, some knees have additional problems because the entire leg is out of alignment or the leg is unstable due to an injury to the anterior cruciate ligament. The loss of a meniscus can sometimes cause the leg to bow and lose its normal alignment. In other cases, patients are born with bowed legs and over the years, the pressure on one side of the knee causes damage to the meniscus and articular cartilage. Some knees that have suffered injury to the anterior cruciate ligament have many giving-way reinjuries which produce damage to the menisci and articular cartilage. At Cincinnati Sportsmedicine, knees with these complex problems are seen all too frequently on a weekly basis.

What Can Be Done?

The good news is that important advances in medical knowledge and surgery now present several options to patients with these problems. Tears to the menisci can often be repaired with an 80-98% success rate, depending on exactly where the menisus is torn. We can also transplant new menisci into the knee from donors. It is important to perform these transplants before too much damage has occurred to the articular cartilage.

Leg alignment problems can be corrected through osteotomy which is a highly successful technique to relieve pressure on the inside (medial) portion of the knee. And, our success rate for arthroscopic-assisted anterior cruciate ligament reconstruction of 94% is one of the highest reported in the country. Patients with these complex problems must realize that all of the problems in the knee must be corrected in order for cartilage restoration procedures to be effective.

Articular Cartilage Procedures

There are several procedures that can be done for damaged articular cartilage. The decision of which procedure to perform is based on the extent of damage seen during arthroscopy and on MRI scans and x-rays. Important indications include the size of the damaged area – both in diameter and depth.

Small articular cartilage lesions (less than 1 cm2 in diameter and extending only partially down into the cartilage; not to the subchondral bone which lies beneath the articular cartilage) are usually treated arthroscopically by debridement and drilling, abrasion, or microfracture. The drilling/abrasion/microfracture procedures all work off of the concept that producing very small holes in the subchondral bone will stimulate a healing response that forms tissue resembling articular cartilage (called fibrocartilage). Clinical research studies have reported mixed reviews of the results of these procedures, and further investigation is needed on the ability of fibrocartilage to reduce pain and restore function over the long-term.

Larger articular cartilage lesions present difficult problems and only a few surgeons are experienced with the newest procedures designed to restore normal articular cartilage surfaces. For younger patients, two procedures are under close study at our Center. These are:

Osteochondral Autograft Transfer (OAT) Procedure

This technique is used for painful articular cartilage lesions which are approximately 2 cm2 in diameter (although size is not an absolute indicator) and extend all of the way down to subchondral bone. The surgeon removes healthy “plugs” of articular cartilage from areas of the knee that bear only a small portion of the patient’s body weight. Then, the plugs are transferred to the areas of damage. The procedure is similar to that of a hair-plug transplant. The number of plugs which are transferred depend on the diameter of the damaged area – anywhere from one to eight plugs have been transferred in our patients. The goal is to transfer as much normal (hyaline) articular cartilage as possible. Studies so far have shown that the cartilage survives the transfer process, and that the majority of patients in short-term studies (followed 2 years after surgery) have benefitted from the procedure. The long-term results of this procedure have not been determined.

Carticel Autologous Cultured Chondrocyte Implantation

This technique is reserved for painful, very large areas of cartilage loss and requires two separate operations. In the first, the surgeon takes a biopsy of healthy articular cartilage cells from the patient’s knee during routine arthroscopy. The cells are sent to a laboratory and cultured over a period of 4 to 5 weeks. Then, the surgeon reimplants the cells in the knee to resurface the area of cartilage loss. The goal is to provide the cells with an environment to mature into tissue similar to that of normal hyaline articular cartilage. The short-term reports of patients who have had this operation show that most have reduced pain and increased function postoperatively. The long-term durability of this operation has yet to be determined.

Cincinnati Sportsmedicine Outlook

“As few as five years ago, we had little to offer young patients with damaged articular cartilage in terms of surgery designed to restore hyaline cartilage. Other procedures could only offer a replacement tissue – fibrocartilage – that probably will not “hold up” over time to all of the stresses incurred by the knee. The Carticel and OAT procedures are promising and may restore enough hyaline-like articular cartilage to provide real benefit to the majority of patients. We are carefully following all patients who receive these procedures at our Center to determine the long-term success rates of these operations.”

Sue Barber-Westin
Director of Clinical Research Studies
Cincinnati Sportsmedicine Research and Education Foundation
SBWestin@csmref.org