San Francisco—February 8, 2012
“Studies have shown that there is only about a 40% return to sport after the microfracture procedure which is the standard of care treatment in the U.S. Over 90% of patients return to sport with the OATS procedure, said Riley J. Williams, III, M.D., a sports medicine orthopedic surgeon at Hospital for Special Surgery (HSS) in New York City and senior investigator of the study. “For those who have isolated cartilage lesions of the femur and are interested in a return to sport in a timely and predictable fashion, the OATS procedure, relative to microfracture, represents a better option.”
For years, researchers have known that erosion of articular cartilage, the soft lining or cushion at the end of bones, can lead to symptomatic osteoarthritis. The cartilage can be damaged from normal wear and tear or from a traumatic injury. Once the cartilage is damaged, it continues to deteriorate. Athletes with progressive osteoarthritis are often forced to stop playing their sport of choice.
Over the years, researchers have developed a number of procedures for repairing cartilage in patients who range from roughly 16 to 50 years of age. The current standard of care is microfracture, an arthroscopic procedure that involves using a tiny pick to punch holes into the base of the damaged cartilage area. This promotes bleeding and allows bone marrow cells to come to the surface of the damaged tissue. As a result, the cells then change into fibrocartilage cells and heal the defect. A study from the HSS Cartilage Registry showed that only about 40% of athletes return to sport after this procedure. “40% is such an abysmal rate of return to sport, which is why we keep looking for other repair methods to help our patients,” said Dr. Williams, who is also director of the HSS Institute for Cartilage Repair.
Another more recently developed procedure is OATS, which involves transferring healthy cartilage tissue from one part of a person’s knee to the damaged area. The transplanted graft includes cartilage and underlying bone and can be performed arthroscopically. A single plug of cartilage may be transferred or multiple plugs may be transferred in a procedure called mosaicplasty. Each plug is a few millimeters in diameter, and when multiple plugs are moved to the damaged area, it creates a mosaic appearance.
Several European studies have shown that the OATS procedure provides a higher return to sport and a longer lasting result, but HSS researchers wanted to verify the results in the U.S. population. “There is an essential difference between American sports and European sports. When you talk about European sports, you are really talking about soccer,” said Dr. Williams, whereas most U.S. patients mostly participate in American football, basketball, running, as well as soccer.
To test the two procedures in the U.S. population, HSS investigators recruited 48 patients who had “potholes” in their cartilage in the area known as the femoral condyle, an area located at the end of the thighbone in the upper half of the knee.
For the control group, the researchers identified 48 patients in the HSS Cartilage Registry who were matched for gender and underwent microfracture for a similar cartilage repair, same lesion size and location.
Clinicians evaluated patients prior to surgery and at one, two, three and five years of follow-up. They used a variety of tools commonly used to measure outcomes in patients undergoing these types of procedures. They used the short-form (SF)-36 health survey, a 36-question scale that includes a gamut of questions about general health and is widely used across all fields of medicine. They used two knee specific questionnaires: the international knee documentation committee (IKDC) scores and the Knee Outcome Survey (KOS). And they used the Marx Activity Level that is scored on a scale from 0 to 16 and gauges a person’s ability to do four activities: running, cutting, decelerating, and pivoting.
They found no difference in the knee outcome surveys or SF-36 form, but they did identify significant differences in the Marx Activity Level. Patients who underwent the OATS procedure had higher scores than patients who underwent microfracture at one year from baseline (score 5.21 vs. 4.11), two years (7.29 vs. 3.71), three years (7.75 vs. 2.91) and five years (8.55 vs. 2.89).
“The Marx activity rating scale correlates directly to the amount of physical activity that you can do at the time of the assessment,” said Dr. Williams. “Patients who underwent the OATS were able to do more sports and more athletic activities compared to the microfracture group at the same time point. We now have another procedure which is likely to result in a return to sport more predictably.”
He said the results are not surprising given that the OATS repair results in a natural cartilage repair whereas microfracture results in a repair comprised mainly of fibrocartilage that has been shown to be biomechanically inferior to articular cartilage.
Dr. Williams is the head team physician for the Nets NBA basketball team and the Major League Soccer's New York Red Bulls.
Other investigators involved in the research are Thomas Wickiewicz, M.D., Russell Warren, M.D., and Scott Rodeo, M.D., from Hospital for Special Surgery; Heather Harnly, M.D., a former HSS fellow who is now at Robert Wood Johnson University Hospital, East Brunswick, New Jersey; and Aaron Krych, M.D., a former HSS fellow who is now at the Mayo Clinic, Rochester, Minn.
Higher Activity Level after Mosaicplasty than Microfracture for Cartilage Defects of the Knee (Paper 282)
Wednesday, Feb. 8, 2:54 p.m.—3:00 p.m. Moscone West, 2024
About HSS | Hospital for Special Surgery
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the ninth consecutive year) and No. 3 in rheumatology by U.S.News & World Report (2018-2019). Founded in 1863, the Hospital has one of the lowest infection rates in the country and was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State. In 2017 HSS provided care to 135,000 patients and performed more than 32,000 surgical procedures. People from all 50 U.S. states and 80 countries travelled to receive care at HSS. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The culture of innovation is accelerating at HSS as 130 new idea submissions were made to the Global Innovation Institute in 2017 (almost 3x the submissions in 2015). The HSS Education Institute is the world’s leading provider of education on the topic on musculoskeletal health, with its online learning platform offering more than 600 courses to more than 21,000 medical professional members worldwide. Through HSS Global Ventures, the institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally.