The studies, which looked at safety and outcomes in both femur-level (above-the-knee) and tibia-level (below-the-knee) OI, were presented at the 2026 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) in New Orleans this week.

“Osseointegration represents a significant advancement in the field of prosthetics for patients who have had a limb amputation, and interest is building rapidly,” said Jason Hoellwarth, MD, director of research in the Limb Lengthening and Complex Reconstruction Service and the Osseointegration Limb Replacement Center. “At HSS, we have performed more OI surgeries than any other hospital in the United States, treating more than 300 patients since 2017. We have found that osseointegration provides improved mobility, comfort and quality of life for patients when compared to a standard socket prosthesis.”    

Study 1: Femur and Tibia Press-Fit Osseointegration - A Comparison of Safety and Outcomes

“There are no studies in the scientific literature focusing on differences in safety and outcomes of patients who underwent transfemoral osseointegration as compared to those who had transtibial osseointegration,” said Taylor J. Reif, MD, an orthopedic surgeon in the Osseointegration Limb Replacement Center at HSS who presented the research. Dr. Reif and colleagues set out to compare safety, clinical, and quality-of-life outcomes in these two patient groups.

Dr. Hoellwarth, co-author of the study, noted that osseointegration was originally considered primarily for patients with femur-level amputations, since they fared much worse with a socket prosthesis than individuals with tibia-level amputations. “It was widely believed that patients with a below-the-knee amputation did well enough with their socket prosthesis and therefore would not derive significant benefit from osseointegration. Our study directly challenged that perspective.”

Researchers reviewed 147 OI procedures: 83 femur-level and 64 tibia-level. Both groups experienced substantial improvements in mobility and overall patient satisfaction, and there were no significant differences in the rate of adverse events.

“Contrary to widespread assumptions, our research found that tibia osseointegration patients have as much to gain from the surgery as femur OI patients,” Dr. Reif noted. “Therefore, any individual with a lower-limb amputation who is dissatisfied with their current socket prosthesis should be evaluated for osseointegration if they would like to pursue that option.”

Study 2: Primary Amputation with Osseointegration Versus Osseointegration for Existing Amputation

HSS researchers set out to compare safety and outcomes in patients who had osseointegration performed at the same time they had an amputation versus the more commonly performed osseointegration in individuals with an existing amputation.

The study included patients who had lower-extremity osseointegration with a minimum of one-year follow-up at HSS. There were 139 OI procedures: 81 femur-level and 58 tibia-level. Fifteen patients had simultaneous amputation and OI (4 femoral and 11 tibial), while 124 patients had OI for an established amputation (77 femoral and 47 tibial). 

The researchers found that both groups of patients—those undergoing osseointegration at the time of their amputation and those who had osseointegration with an existing amputation—achieved comparable gains in mobility and quality of life. There was no significant difference in adverse events between the two groups.

“Our research challenges the current paradigm that individuals with amputations should first try conventional socket prosthetics and only consider osseointegration if they are dissatisfied with their prosthesis,” said Dr. Reif, who presented the study. “It would be reasonable to offer simultaneous amputation and osseointegration to select, well-informed patients who prefer to bypass the trial of a socket prosthesis.”

Study 3: Safety and Early Experience of Osseointegration Limb Replacement with Custom-Fit Implants

HSS researchers set out to review the early outcomes of osseointegration with custom-made 3D-printed implants, which may be required for certain patients to obtain an ideal fit.

“Some designs of press-fit osseointegration implants have standard curvatures and contours with patient-specific length, leading to difficulty fitting the shape of the residual bone in some cases,” Dr. Hoellwarth explained.

Dr. Reif, who presented the study at the AAOS meeting, noted that additive manufacturing using electron beam melting (EBM) allows the production of precision osseointegration implants to achieve an optimal fit, making it possible to reconstruct nearly any residual bone segment to meet an individual’s anatomical needs.

The HSS researchers retrospectively reviewed the records of 19 patients at HSS who underwent osseointegration with custom 3D-printed implants planned from a preoperative CT scan. Patients included those who had above-the-knee, below-the-knee and above-the-elbow osseointegration procedures between May 2024 and March 2025.

The investigators found large, statistically significant improvements in patient-reported outcome scores following OI, and a significant increase in prosthetic use was observed in those who had used a socket prosthesis before OI surgery.  

Dr. Reif noted that the custom EBM osseointegration implants avoided intraoperative distal chip fracture, which can sometimes occur when using standard OI implants, and there was no loosening of the custom implants. “We found that short-term functional outcomes were similar to standard osseointegration implants,” he added. “Further studies are warranted to assess the long-term outcomes and durability of custom implants.”

Study 1 - Femur And Tibia Press-Fit Osseointegration - A Comparison of Safety and Outcomes (Zachary Glassband BA, Taylor J. Reif MD FAAOS, S. Robert Rozbruch MD FAAOS, Jason S. Hoellwarth MD)

Study 2 - Primary Amputation with Osseointegration Versus Osseointegration for Existing Amputation (S. Robert Rozbruch MD FAAOS, Mohamed Abdelaziz Elghazy MD, Zachary Glassband BA, Taylor J. Reif MD FAAOS, Jason S. Hoellwarth MD)

Study 3 - Safety and Early Experience of Osseointegration Limb Replacement with Custom-Fit Implants (S. Robert Rozbruch MD FAAOS, Zachary Glassband BA, Jason Hoellwarth MD, Taylor Reif MD FAAOS)

Osseointegration prostheses are a relatively new form of prosthetic technology. The approach involves surgically installing a titanium rod into a patient’s remaining bone—such as the tibia or femur in the leg—which in turn attaches to a prosthesis that allows ambulation. The technology avoids the need for traditional sockets against which limb stumps rest, an interface that produces friction that can generate significant pain and discomfort for amputees and frequently requires repair or revision.

Although osseointegration devices are available to patients in Europe and elsewhere, the U.S. Food and Drug Administration has yet to approve the technology. But the agency allows a limited number of patients to receive the implants through humanitarian exceptions.

“This is a disruptive technology to improve the life quality of amputees,” said study co-author S. Robert Rozbruch, MD, Chief of the Limb Lengthening and Complex Reconstruction Service and Director of the Limb Salvage and Amputation Reconstruction Center at HSS. “With a direct skeletal connection of the prosthetic limb, amputees report big improvements in function, comfort, balance, proprioception and even emotional connection with their limb.”

For the new study, Taylor J. Reif, MD, an orthopedic surgeon and a member of the Limb Lengthening and Complex Reconstruction Service, Dr. Rozbruch and their colleagues reviewed the medical records of 31 men and women who underwent osseointegration procedures at HSS starting in October 2017 under compassionate use exceptions. Of those, 18 had implants in the femur, or thigh bone, and 13 had implants in the tibia, the bone below the knee.

The primary outcome of the study assessed changes in the Questionnaire for Persons with a Transfemoral Amputation (QTFA), which patients complete before and after surgery. The researchers used the same questionnaire for patients with tibial amputations. They also gathered data on a range of quality-of-life measures including patient-reported functional activity, mental health, pain and self-image, as well as adverse events such as serious infections, fractures at the site of the implant and other complications of the procedure.

Researchers found that scores across all domains of the QTFA improved significantly throughout the study period. Prosthetic mobility rose from 49.7 to 81.4, while prosthetic problems fell from 46.4 to 9.1. Patients also experienced substantial gains in function with the implants, as measured by 2- and 6-minute walking tests.

Dr. Reif said the benefits of the devices extend beyond the raw numbers. “The scores going up is great, but that doesn’t necessarily capture what we’re seeing in the clinic, which is smiles on people’s faces and the expressions of gratitude for how much their lives have changed. It’s totally life-altering.”

Although some patients did experience early complications, nearly all (93%) were managed without removing the implant. Encouragingly, while some patients developed minor infections where the titanium post exits the skin (an opening called a stoma), most of these resolved with the use of oral antibiotics. Only one patient had an infection in the bone itself leading to removal.

The bond between the titanium implant and the bone is so strong that patients are able to rapidly resume physical activity. In some cases, patients can return to vigorous, weight-bearing exercise such as running within six months to one year after the procedure.

As the data showed, patients who seek osseointegration prostheses tend to be young, and most had sustained catastrophic injuries to their legs in vehicular accidents or other traumatic events. “The older population of patients have become accustomed to their sockets or using a wheelchair,” explained Dr. Reif. “But as this technology expands and more surgeons start to employ it, I think the age that these are implanted also will expand in both directions.”

He added, “No implant has a perfect track record, but when you combine the functional gains that these patients are experiencing with improvements in their quality of life, a small risk of infection or fracture is acceptable to them, as well as to the orthopedic community.”