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HSS Surgeon Launches Study of Novel Treatment for Knee Cartilage Defects and Osteoarthritis

Orthopedic surgeons at Hospital for Special Surgery (HSS) in New York City are enrolling patients for a clinical trial of an experimental technology for treating cartilage defects and osteoarthritis of the knee.

The Agili-CTM implant (CartiHeal, Inc.) is used for the treatment of painful knees with joint surface lesions. The implant, which is made of aragonite, a form of coral based calcium carbonate, may help to stimulate the growth of healthy cartilage and bone, through infiltration of blood and bone marrow cell. Andreas H. Gomoll, MD, sports medicine surgeon at HSS, who is conducting the trial at the institution, says the technology has shown promising results in preclinical studies as well as human studies previously conducted in Europe.

Damage to knee cartilage, also termed osteoarthritis in its more severe form, is increasingly common in the United States1.The condition, which involves damage to the joint cartilage and its underlying bone, can be caused by several factors, including traumatic injury, repetitive strain or genetics.

The most common procedures for patients with cartilage damage are microfracture and debridement surgeries. In debridement the surgeon shaves the damaged cartilage, while in microfracture the orthopedic surgeon makes tiny holes in the surface of the joint. The holes allow increased flow of blood to the affected area, promoting the formation of fibro-cartilage.

Although debridement and microfracture surgeries works reasonably well for many people, it’s not universally effective -- prompting the search for alternative treatments. Previous surgical approaches to treating cartilage damage typically involved patients with localized damage and little or no damage to the bone. The Agili-CTM study on the other hand, is the first trial of a cartilage repair implant that also allows people with more extensive cartilage damage, so-called early osteoarthritis, to be enrolled. Early osteoarthritis is marked by more extensive damage than is traditionally treated with cartilage repair. Patients with end-stage, or bone-on-bone osteoarthritis, however, are not eligible for the trial.

“What is potentially groundbreaking about this, and what this study does that no other surgical study has done before, is go to the realm of early osteoarthritis. It opens a potential population that is significantly larger than that we can currently treat,” he says.

Although no therapy is likely to prevent future joint replacement surgery, Dr. Gomoll says that even delaying the need for surgery by a decade or so could allow some people to avoid revision procedures later in life.

Another potential advantage of the technology, Dr. Gomoll says, is that Agili-CTM is an “off-the-shelf” product that does not require customization for individual patients or special storage and handling. While prior studies of synthetic plugs made from resorbable plastic were unsuccessful, “this new study is a beautiful way of using nature to heal nature by using coral-based material to treat cartilage damage in patients”, he says.

In this study the patients are randomly assigned to receive either the Agili-CTM implant or the current standard of care, microfracture or debridement surgeries, in a ratio of 2:1 (for every two patients that receive the Agili-C implant, one patient will receive the current standard of care). The study in not blinded and the patient knows what kind of treatment they received.

The outpatient procedure is performed under general or local anesthesia and takes approximately one hour. Patients can expect to spend roughly one month on crutches after surgery.

Participants in the trial will be followed over the next two years and assessed on several measures, including pain, daily functioning, and their ability to return to physical activities such as work and sports. They also will undergo periodic X-ray and MRI procedures to track physical changes in the joint.

Over 180 patients, out of minimum 250, have been already enrolled into the study in leading centers in Europe and US. The HSS researchers are now enrolling patients as well. To qualify for the study, patients must be aged 21 to 75 years; have visible cartilage defects or mild to moderate knee osteoarthritis (not involving bone-on-bone contact); and have a body mass index less than 35.

For more information, contact Dr. Gomoll at


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 14th consecutive year), No. 2 in rheumatology by U.S. News & World Report (2023-2024), and the best pediatric orthopedic hospital in NY, NJ and CT by U.S. News & World Report “Best Children’s Hospitals” list (2023-2024). In a survey of medical professionals in more than 20 countries by Newsweek, HSS is ranked world #1 in orthopedics for a fourth consecutive year (2023). Founded in 1863, the Hospital has the lowest readmission rates in the nation for orthopedics, and among the lowest infection and complication rates. HSS was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center five consecutive times. 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, as well as in Florida. 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. In addition, more than 200 HSS clinical investigators are working to improve patient outcomes through better ways to prevent, diagnose, and treat orthopedic, rheumatic and musculoskeletal diseases. The HSS Innovation Institute works to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is a trusted leader in advancing musculoskeletal knowledge and research for physicians, nurses, allied health professionals, academic trainees, and consumers in more than 165 countries. 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.