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April 10, 2021  

Dr. Kenneth Zaslav: Applying New Techniques to Cartilage Repair

September 28, 2000

Applying New Techniques to Cartilage Repair

By Neal Patel, Knee1 Staff

Articular cartilage damage can be one of the most debilitating of knee injuries. In the past, if procedures such as debridement and chondroplasty failed to provide relief, patients were often left in a partially disabled state. However, today there is hope for such patients in the form of Autologous Chondrocyte Implantation (ACI), a technique that uses a patient’s own cartilage cells to repair a defective area of articular cartilage. Dr. Kenneth Zaslav was one of the first U.S. doctors to train in the ACI technique under its Swedish pioneer, Dr. Peterson, and was also the first to perform the procedure in the commonwealth of Virginia. Moreover, Dr. Zaslav was recently selected as the first clinical investigator to have his site approved for the FDA’s newest study on cartilage implantation, the STAR Study, which compares Genzyme Tissue Repair’s Carticel autologous chondrocyte implantation to other techniques for cartilage restoration.

Dr. Zaslav received his medical degree from the Albert Einstein College of Medicine in the Bronx, New York, and completed his orthopedic surgery residency at the State University of New York at Stony Brook. Currently, Dr. Zaslav is President and Chief of Sports-medicine at The Advanced Orthopedic Centers in Richmond, Virginia and is a Clinical Assistant Professor of Orthopedic Surgery at Virginia Commonwealth University, Medical College of Virginia Campus. Dr. Zaslav’s goal is to “bring the highest level of new technology and diagnostic treatment for injuries to [his] athletes while adhering to rigid principles of scientific method and research and providing compassionate care to [his] patients.”

MedTech1: How did you get involved in Autologous Chondrocyte Implantation (ACI)?

Dr. Zaslav: By no means am I the pioneer of ACI. Dr. Peterson in Sweden developed the technique about seven years ago. Four years ago, Dr. Peterson trained a group of American doctors interested in the procedure, and I was fortunate to be a member of that first group. Approximately three years ago, I performed the first autologous chondrocyte transplantation in Virginia. The procedure went very well. The patient was a SWAT team officer from the Fredricksburg, Virginia Police. He was an extremely active athlete and unfortunately, during a training parachute jump, he landed awkwardly on his knee and shattered his trochlear groove, the groove under the kneecap. Prior to the ACI, he had had three or four unsuccessful operations, including a chondroplasty, where microfractures are made in the bone below the cartilage defect; a Fulkerson osteotomy, which is a re-alignment and elevation of the tibial tubercle to take pressure off of the knee; and a debridement, which involves removing the defective cartilage from the lesion. Due to the failure of these procedures, the patient was out of work and unable to participate in certain activities, such as playing sports and riding a bike with his wife and children. As a result, he was a perfect candidate for the ACI. His cartilage defect spanned 80 percent of the trochlear groove, which is one of the largest defects we have repaired with ACI. However, the large size was attractive to us because with smaller lesions, you can always try other remedies. Today its been over three years since the ACI and he’s working as a detective on the police force and doing everything he wants to do, including skiing in Vail. He’s definitely a happy guy.

MedTech1: How do you select a patient for ACI and what are the benefits?

Dr. Zaslav: There are several criteria a patient must meet in order to qualify for an ACI. First, they must have no evidence of real arthritis. In addition, they must not present with a collapse or misalignment of the knee. If these conditions exist, they must be fixed before an ACI is attempted. Furthermore, it is also my belief that the patient must have failed at least one attempt at chondroplasty. Currently, chondroplasty is the routine procedure to repair articular cartilage damage. It’s a quick and easy ten-minute arthroscopic procedure that involves entering the lesion, debriding out the loose tissue, and making a microfracture hole on the bone beneath the defect to bring blood supply to heal the lesion with new fibrous cartilage. The patient can return to normal activity in two to three months as opposed to six months to a year with ACI. Thus, ACI should be used as an alternative only when chondroplasty fails.

The results of ACI have been promising. In the United States, we have had about 78 to 80 percent good to excellent results of alleviating pain and returning patients back to activities of daily life. Many patients go back to sports; however, we don’t promise that result to everyone. If the patient has a sedentary job, they can be back to work within two to three months. Most patients are performing activities of daily living within six months and start participating in sports after one year.

MedTech1: What does rehabilitation after an ACI involve?

Dr. Zaslav: Patients are put on crutches and are non-weight bearing for a period of four to six weeks after the procedure. During this period, only a passive range of motion is encouraged. Beyond crutches, rehabilitation depends on the location of the lesion within the knee. If the lesion is in the trochlear groove, or kneecap mechanism, sheer forces, the very great forces across the knee, occur with active extension and exercises that rely on the quadriceps muscles. Thus, for these patients, we are very protective of that type of motion. Yet, if you lock the patient in a brace, they can bear weights safely. Whereas if the lesion is in the femoral condyle, which is the more common lesion, those patients can have full range of motion immediately; however, they still have to be non-weight bearing.

MedTech1: Do you think ACI will ever displace chondroplasty as the procedure of choice for articular cartilage repair?

Dr. Zaslav: I think chondroplasty will remain the treatment of choice for small lesions because over fifty percent of patients experience good results with the procedure and it’s a small arthroscopic surgery. However, the problem with chondroplasty and other procedures similar to it is that they do not form hyaline-like cartilage, which is the durable cartilage that is naturally in your joint. Instead, they form fibrous cartilage. Therefore, the patient will feel better temporarily because the fibrous cartilage is filling the defect, but this cartilage eventually wears out because it doesn’t have the ability to bear the load of the joint. Chondroplasty is consistently successful for small lesions because usually there is enough hyaline cartilage around the defect to support the majority of the load and the new fibrous cartilage smoothes out the defect without having to bear a heavy load. The reason that chondroplasty fails is that often the lesion is too big and within two years, the fibrous cartilage wears away. On the other hand, with ACI, it has been shown that hyaline-like cartilage forms. The new cartilage is not as strong and not structurally the same as natural hyaline cartilage; however, it’s hyaline-like cartilage because it has the chemical markers for hyaline cartilage even though its architecture is different. The amazing part is that we have found that patients who are doing well after one year are doing even better after two years and still better after three years. Therefore, we hope that there is a maturing process of the cartilage occurring with the ACI that hasn’t occurred in previous articular cartilage surgery.

Overall, I believe ACI is going to keep its place as an alternative for patients who failed with chondroplasty. ACI will always be available for patients who are having persistent symptoms and therefore, willing to take on the significant down time that it takes to get better. We hope that by doing the ACI on younger patients with chondral injuries, we will decrease the need for total knee replacement twenty years down the line for those patients with traumatically induced cartilage defects.

MedTech1: I understand that you are involved with the STAR Study. Could you please explain the study?

Dr. Zaslav: The STAR study is an FDA study requesting that Genzyme Tissue Repair, the developers of Carticel, analyze how their particular technique compares to other techniques for cartilage restoration. The data collected until now has come from prospective studies; however, none of these studies have compared two different types of treatment. Dr. Freddie Fu among others attempted to start a prospective randomized double-blind study comparing chondroplasty and ACI. Since the study was randomized and double-blind, patients would go into surgery not knowing which procedure they would undergo. Some would have a chondroplasty, allowing them to return to activity within two to three months and others would have an ACI, potentially keeping them out of activity for up to a year. As a result, most patients were reluctant to sign up for the study since not knowing which procedure they would receive made them uncomfortable. Chondroplasty is still the procedure of choice for an initial attempt to remedy articular cartilage damage.

Therefore, the FDA designed the STAR study as a more feasible way of assessing the usefulness of ACI. In order to qualify for the study, a patient must have already had a cartilage restoration procedure other than ACI, such as chondroplasty or OATS (osteoarticular autografts), within the last four years that has failed, leaving them with persisting symptoms. After having the ACI, the success or failure of the procedure will be tracked. The patient must promise to come in every year for follow-up for a certain number of years in order to track their progress. An independent physician will look at all the records from the first surgery and also from the ACI. What we hope to show is that where chondroplasty or some other procedure failed, at four years, patients are still doing well with the ACI. This study represents a new type of protocol as far as orthopedic treatment; however, so far it has been successful and people have been enrolling. I have already enrolled five patients at my clinic. This study represents a type of protocol common in evaluation of cancer drugs where time to treatment failure is compared between a previous procedure and prospectively this new procedure.

For more information regarding Carticel or the STAR Study, please contact Genzyme Tissue Repair at 1-800-453-6948 or visit the Web site at

To contact Dr. Zaslav, send e-mails to [email protected]

Last updated: 28-Sep-00

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