“We are immensely grateful and thank Dr. Roberts for his many years of leadership as a clinician, scientist and educator,” said Douglas E. Padgett, MD, surgeon-in-chief and medical director at HSS. “Dr. Demetracopoulos’s impressive expertise will continue to drive clinical research, innovation, and education forward to provide the highest quality care possible to patients.”  

Dr. Demetracopoulos is an orthopedic surgeon specializing in foot and ankle surgery. Internationally recognized in the field of total ankle replacement, he also directs the multidisciplinary Total Ankle Replacement Center at HSS, which brings together a specialized team of doctors, nurses, and physical therapists focused on advancing the treatment of ankle arthritis, with the goal of improving outcomes for patients.

“I am honored to lead and collaborate with colleagues who are top specialists in orthopedics and to continue the record of excellence of the Foot and Ankle Service,” said Dr. Demetracopoulos. “Our multidisciplinary model of evidence-based care will keep HSS at the forefront and offer patients access to advanced diagnostic tools and treatment options to ensure the best possible outcomes.”

Dr. Demetracopoulos earned his MD degree at Johns Hopkins School of Medicine. He completed his residency training at HSS, and his fellowship training at Duke University Medical Center.  His research in ankle arthritis and ankle replacement has earned distinctions from the American Orthopaedic Foot and Ankle Society and the International Federation of Foot and Ankle Societies, and grant support from the Orthopaedic Research and Education Foundation and the Arthritis Foundation.

Kaler, who is from Long Island, says the surgery changed her life. She can now engage in activities most people take for granted – walking normally without pain, wearing shoes she likes, being able to do her job, working in her backyard.

“You have no idea how grateful I am. Before the surgery, my left ankle was collapsing, it could barely support my weight,” says Kaler, a slim 5 foot 7. “All my shoes were worn out on one side.” Her ankle was so unstable, she lived in fear that she would fall or break it, despite the rigid plastic brace she wore from her foot to her knee, day in and day out. She could only wear one type of shoe that she needed to replace every three months.

As a child, Kaler recalls constantly twisting her ankle. Her parents took her to several doctors, and she was given a shoe insert to help with her high foot arches. Years later, arthritis set in, and the pain worsened and became more debilitating. Cortisone shots could only do so much, and she resumed the search for a long-lasting solution. Four doctors said nothing could be done. One orthopedic surgeon said the problem might be corrected with four separate surgeries, which she declined.

Then she learned about total ankle replacement during an appointment with a doctor at HSS Long Island. It’s a complex surgery performed by relatively few orthopedic surgeons, and she was referred to Dr. Demetracopoulos, director of the HSS Total Ankle Replacement Center at the main hospital in Manhattan.

“One of the few centers of its kind, we have a team of foot and ankle specialists, anesthesiologists, radiologists, nurses and physical therapists who have extensive experience in ankle replacement,” he explains. “We strive to provide the best possible care for each of our patients and have grown our volume to become one of the top institutions nationwide in ankle replacement.”

Kaler says her consultation with Dr. Demetracopoulos gave her hope, and she would not be disappointed. She had the surgery in April 2021. “He saved my life. I never cry, but I cried in front of him, I was so grateful,” she says.  

“Ankle replacement is considered when patients are no longer able to manage arthritis pain with nonsurgical treatments such as physical therapy, appropriate footwear, an ankle brace or anti-inflammatory medication,” Dr. Demetracopoulos explains. “They have consistent pain that limits their activities and affects their quality of life.”

Like other types of joint replacements, the surgery involves replacing the damaged bone and cartilage in the ankle with a prosthesis. The implant, made of metal and plastic, has the shape of a natural joint and seeks to provide normal, pain-free movement.

The last 15 years have brought vast improvements in ankle replacement implants, technology and surgical techniques, making it a viable option for many patients suffering from severe arthritis, says Scott Ellis, MD, another orthopedic surgeon specializing in foot and ankle surgery at HSS.

One of the most noteworthy advances in ankle replacement is patient-specific instrumentation, or PSI, Dr. Ellis says. It entails obtaining a CT scan of the patient’s ankle and developing a customized presurgical plan tailored to the individual’s anatomy. “PSI has been a game changer. It enables us to choose an implant that is the perfect size and map out a very precise surgery for optimal alignment and positioning,” he says. 

For people considering an ankle replacement, the first step is a thorough assessment of the ankle and the foot, and a discussion of patient goals and expectations. Imaging and other tests determine if a patient is a candidate. For someone whose ankle is very stiff with limited mobility or a severe deformity, a fusion of the ankle bones might be a better option and is also very successful in relieving pain, the HSS experts say. An ankle fusion would also be a better option for someone with weakened bones or osteoporosis. The benefit of ankle replacement over fusion is better movement after surgery.

Sometimes an ankle replacement needs to be combined with another procedure, as it was in Kaler’s case. “Hers was a complex surgery. She had a type of foot that predisposed her to ankle instability,” Dr. Demetracopoulos explained. “In addition to treating her arthritis with the ankle replacement, we needed to treat the instability by repairing the ligaments in her ankle and by correcting the alignment in her foot, so it was in the right position.” 

Kaler says she experienced no pain after surgery, which Dr. Demetracopoulos attributes to advances in nerve block anesthesia and pain management protocols after the procedure. He notes that each patient experiences pain differently, though.  

The HSS doctors expect 90 percent of ankle replacements to last 10 years. If the implant wears out, patients could be candidates for a revision ankle replacement or an ankle fusion. The physicians follow and monitor patients in a joint replacement registry at HSS. “One of our core missions at HSS is not only to deliver the care and do the best surgery we can for our patients, but to collect data over time that we can share with other surgeons and clinicians,” Dr. Demetracopoulos says.  

Kaler says the surgery has enabled her to regain her confidence. She can now drive her stick-shift Mini Cooper and carry out her demanding job responsibilities at a major home improvement store. “I’m all over the place, to the point where my friends and colleagues are saying, ‘slow down,’” she adds, making up for lost time and living life to the fullest.

The research paper, titled, "The Use of Three-Dimensional (3D) Biometric Measurements to Predict Additional Alignment Procedures in Total Ankle Replacement" was presented today at the American Academy of Orthopaedic Surgeons Annual Meeting in Las Vegas. 

"The foot and ankle is a highly complex anatomical and biomechanical structure, and preoperative evaluation of deformities in patients undergoing total ankle replacement is challenging," said Constantine A. Detracopoulos, MD, an orthopedicsurgeon specializing in foot and ankle surgery at Hospital for Special Surgery and senior investigator. "The final decision to perform associated corrective alignment procedures and soft tissue balancing is made during surgery following insertion of the ankle replacement components."

Conventional x-rays are limited in their ability to characterize foot and ankle deformities due to their two-dimensional nature, according to Cesar de Cesar Netto, MD, who presented the study. The complexity of the foot and ankle and the importance of weight-bearing in diagnosis have prompted the use of standing CT scans to provide a more complete 3D picture of alignment and deformities, he noted. 

At HSS, the weight-bearing CT is standard of care. "This is a growing research field in foot and ankle orthopedics. The goal is to determine how this technology can improve our patient outcomes," Dr. Demetracopoulos noted. 

The researchers launched a pilot study to determine if the information provided by the standing CT could improve surgical planning prior to ankle replacement. Software designed for the scanner was used to calculate a new biometric measurement called the Foot and Ankle Offset (FAO). Surgeons could use this information to assess the alignment of the foot underneath the ankle and predict which additional surgeries, such as tendon transfers or osteotomies, might be needed during total ankle replacement. 

"Proper alignment is critical to the success of ankle replacement surgery and the longevity of the implant," said Dr. Demetracopoulos, who noted that the study, which included 12 patients, was the first of its kind. "The key in ankle replacement is to optimize not only the alignment of the ankle, but the alignment of the foot underneath."

The researchers found that an increased FAO significantly predicted the number of additional alignment procedures needed during ankle replacement. "We believe that the use of biometrics and measurements provided by the CT scan can enhance the preoperative assessment and surgical planning of total ankle replacement," Dr. Demetracopoulos said. "Future research will determine if it leads to improved outcomes, as well."

The group, led by Constantine Demetracopoulos, MD, foot and ankle surgeon at HSS, received the honor for their paper, "Influence of Tibial Component Position on Altered Kinematics Following Total Ankle Arthroplasty During Simulated Gait." The article describes experiments to determine how surgical replacement of the joint can affect patient mobility after the procedure.

The surgeon team consisted of Drs. Jonathan Deland, Scott Ellis, and Guilherme Saito, who performed the study in conjunction with Daniel Sturnick in the Biomechanics Department at HSS. The research team utilized a unique robotic gait simulator, which is able to reproduce normal walking gait using human cadavers. The simulator was developed through a generous donation by Herbert Black, owner and CEO of American Iron and Metal Company, under the leadership of Dr. Jonathan Deland, foot and ankle surgeon at HSS.

The findings from the study could help surgeons fine-tune their techniques during ankle replacement to reduce the risk that patients experience complications later on, said Dr. Demetracopoulos. It may also help companies that make artificial joints design implants that are more anatomically friendly and less prone to wear.

"For patients who have ankle arthritis and have an ankle replacement, how we do the replacement and how we position the replacement device is critical to matching the kinematics of normal gait and the success of the procedure," Dr. Demetracopoulos said.

Total ankle arthroscopy (TAA), or ankle replacement surgery, is an option for patients with severe arthritis of the joint. For the procedure, surgeons replace the patient’s diseased ankle with a prosthetic joint composed of metal and plastic. Although the procedure is becoming more common, it is much less so than knee or hip replacement procedures, which number in the hundreds of thousands per year each. As a result, relatively little is known about the best ways to perform the procedure, particularly when it comes to positioning the replacement parts in the bone, or how variations in surgical techniques may affect outcomes.

Ankle replacement surgery is thought to provide patients greater flexibility and motion in the joint than an alternative procedure, ankle fusion. However, despite the significant improvement in pain and mobility following ankle replacement, whether an ankle prosthesis can restore normal walking gait remains unclear. 

For the new study, Dr. Demetracopoulos and his colleagues sought to learn how placement of the ankle implants during TAA affects range of motion. To do so, they implanted artificial ankles (Salto Talaris, Integra LifeSciences) into eight leg sections obtained from cadavers. (The use of cadavers allowed the researchers to more accurately assess ankle motion before and after implant surgery, and also avoided having to expose living patients to excessive radiation from imaging tests.)

To monitor motion, Dr. Demetracopoulos’ group surgically grafted ligaments and tendons from the original joint to sensors. The legs were mounted on a robotic platform with computer software that tracked movement of the ankle in three dimensions: up/down bending of the ankle, side-to-side tilting, and rotation of the bones. "As you bend your ankle up and down, the bone is doing a little bit of all three: From the very top to the very bottom, it’s bending down, it’s tilting and it’s rotating. It doesn’t move like a hinge," Dr. Demetracopoulos explained.

Using the robotic platform to simulate a walking gait, the HSS team found that ankle motion appeared to be restored in two degrees of movement--up/down and side to side tilting. However, rotational motion was significantly greater than before the procedure.  

"We were able to show that the technique of how the replacement is positioned is what drives that rotation," Dr. Demetracopoulos said.

The HSS researchers say the asymmetrical design of the implant used in the study—one of the oldest devices to reach the market that is currently still in use— may play a role in their findings. Newer implant designs may be less prone to such rotational motion, and the group is in the process of trying to evaluate those devices.