Although digital twin (DT) technology was introduced less than 25 years ago, it’s already opened the door to a wide range of healthcare applications, and that now includes orthopedic surgery. In November 2025, Hospital for Special Surgery (HSS) in New York City received a $10 million gift from Lauren and Robert Steers to develop the HSS Digital Twin Platform. This 4-year project is designed to advance orthopedic surgical care, focusing on a range of joints and diverse procedures.

A DT platform is, essentially, a virtual replica of a patient’s anatomy, created by software. DT helps to eliminate trial-and-error because physicians can monitor a patient’s “twin” in real time, then experiment with treatment strategies without traditional safety risks.

A DT works by using multimodal data on clinical, hereditary, molecular, environmental, and social factors, as well as data from wearable devices, to build a virtual entity of the physical patient. Then, dynamic simulations allow doctors to work on precise, personalized options in conjunction with that entity, incorporating real-time data encompassing the patient’s health status. Simulations could also conceivably allow for a patient to avoid invasive procedures, if other treatment options are shown to be viable.

At HSS, the multidisciplinary team working on the DT project consists of surgeons, radiologists, biomechanical engineers, and artificial intelligence and data specialists. Using the DT tool, they’ll focus initially on the knee. 3D imaging will be used to create a patient’s anatomic replica and then treat musculoskeletal injuries. Surgeons can then run simulations driven by data in real time to plan surgery, make decisions intraoperatively, and predict how well a patient will do, which in turn will allow patients to better understand their conditions. 

“In our pipeline, we take an MRI of the knee and autosegment it to create a 3D model,” said Andrew D. Pearle, MD, attending orthopedic surgeon, chief emeritus of sports medicine, and program director of the HSS Digital Twin project. “You can integrate this 3D MRI data with a physics-based computational model, essentially adding virtual ligaments to the knee to simulate how it will behave in the real world. We can also tune ligaments — make them tighter or looser — based on the injury pattern.”

How the HSS DT Platforms Were Constructed 

The DT platform is based on over a decade of work by HSS orthopedic surgeons and biomechanical engineers. This team evolved a computational model of the knee to incorporate AI and advanced image processing. 

“We collaborated with investigators from the University of Vermont who had gathered a large case-control data set of high school athletes with ACL [anterior cruciate ligament] tears and their teammates who were uninjured,” Pearle said. “We had MRIs on both groups of these kids and used that information to create their digital twins, integrating it into our pipeline. The breakthrough here is that you’re not taking months or weeks to create a digital twin. You’re using real-world patients and creating digital twins at scale.”

One of the initial clinical applications using the DT platform involved determining whether patients needing ACL revision surgery could also benefit from a slope-reducing tibial osteotomy. The DT platform was able to model the procedure one degree at a time, so that surgeons could tell how forces and knee motion would change. 

Pearle said that the tool may also speed up rehab time. “You can push recovery because you know how the knee will behave,” he explained. “With the digital twin, the more data you put into it, the more compelling simulations you can get. You can run all different kinds of data and modeling.” 

The Potential to Transform Care at HSS 

Pearle sees the HSS Digital Twin Platform as the future of precision orthopedic care, which may extend to injury prevention. “One idea that we have is that someday we can actually screen patients who are at higher risk for ACL injuries, such as female high school student athletes,” he said. His team will do intensive work on scaling up knee applications, and then also focus their attention on creating DTs to treat shoulder and hip injuries. 

Pearle also thinks that a DT care companion can be developed for online access, so that patients can see and understand comprehensive musculoskeletal data. This new wealth of information could conceivably replace a medical record. The goal, he said, “is that you make everything personalized, you meet patients where they are and find a solution. Science is great in the lab, but it doesn’t do the patient any good unless it helps in real life.”

Successes of DT in Other Areas of Clinical Care and Research 

DT technology has had an extensive impact on positive clinical outcomes. For example, in patients with heart disease, the use of DTs to conduct virtual testing to guide antiarrhythmic drug selection resulted in reduced recurrence rates compared with not using a DT (40.9% vs 54.1%). DT applications have also been shown to improve survival rates and/or improved patient outcomes in many other fields, including oncology and respiratory disease, as well as improvements in diabetes management and surgical intervention. 

In terms of research, DT is showing great promise in improving the execution of clinical trials. DT models are currently being used to simulate patient responses, which can eliminate issues raised through randomized controlled trials — for example, the inability to study rare illnesses or involve high-risk patients. DT can also eliminate the need for placebos and cut the odds of adverse drug reactions. 

Pearle disclosed serving as a consultant for Osstec.