The first of the three studies, “Aspirin Versus Potent VTE Chemoprophylaxis (VTEC) in Total Knee Arthroplasty: Reduced Postoperative Pain and Complications with Aspirin Use,” examined the experience of total knee arthroplasty (TKA) patients with postoperative pain who were also taking blood thinners. The study included 28,169 patients treated between 2016 and 2023; 18,413 received aspirin while 9,756 received a potent VTE.. Patients were monitored for 90 days following their procedure. The findings suggest that aspirin should be considered the preferred option for reducing postoperative pain in TKA patients.

Patients on more-potent blood thinners tend to experience more pain, swelling and inflammation after surgery, said Brian P. Chalmers, MD, a hip and knee surgeon at HSS and one of the study’s authors. “We have always known that non-steroidal anti-inflammatory medications can improve patients’ swelling and inflammation after surgery. However, the traditional thought and belief has been that we should avoid those in patients on anticoagulation. Our data show there is less risk and less postoperative pain when these patients are utilizing aspirin.”   

A second study, “The Effect of Concomitant Use of Potent Anticoagulation and Anti-Inflammatories on Early Outcomes of Total Hip Arthroplasty,” retrospectively evaluated 5,881 total hip arthroplasty patients who were on anticoagulation. The surgeries were performed between 2016 and 2023; of those patients, 4,867 were concomitantly prescribed NSAIDs and 1,040 received anticoagulation alone. Researchers concluded that the concomitant use of NSAIDs in patients on anticoagulants did not increase the risk of wound-related bleeding complications.

“The conventional thinking has often been that patients on an anticoagulant should not be on an NSAID, that there is going to be bleeding, more risk of wound problems and additional complications. But based on our retrospective data, we did not see increased risk in patients using both anticoagulation and NSAIDs. We did see some additional benefits, including less pain and a somewhat easier recovery,” Dr. Chalmers stated. “NSAIDs appear to be safe in this setting and may help decrease postoperative pain and reduce opioid use following surgery.”

The final study, “Cefazolin and the R-1 Side Chain: Why Your Joint Arthroplasty Patients With Cephalosporin Allergy Can Safely Be Given Cefazolin,” assessed the safety and effectiveness of the antibiotic Cefazolin in patients with documented cephalosporin allergies. This is the first study to evaluate these questions.

From 2016 to 2024, researchers compared patients with a reported cephalosporin allergy who received perioperative cefazolin with those who received alternative antibiotic prophylaxis. This study included 89,993 hip and knee arthroplasty patients. Of these, 1,267 had a documented allergy. The study resulted in zero incidence of IgE-mediated or “severe” type IV allergic reactions, concluding that cefazolin can be safely administered to most patients with an existing cephalosporin allergy.

“When patients have a mild allergic reaction, there is often a reflex to give them another antibiotic in a different family of drugs. However, alternative options aren’t always as effective,” said Matthew S. Austin, MD, hip and knee surgeon at HSS and a study author. “Clear protocols should be put in place to guide decision-making when managing these types of allergies.”

These findings underscore HSS’s ongoing commitment to challenging conventional assumptions and using data-driven research to refine perioperative care. The studies highlight how targeted medication strategies can improve safety, reduce complications and enhance outcomes for patients undergoing hip and knee arthroplasty.

Study Details 

“Aspirin Versus Potent VTE Chemoprophylaxis in Total Knee Arthroplasty: Reduced Postoperative Pain and Complications with Aspirin Use”

 Alex Anatone, Alexis Gabriel Gonzalez, Richard Hwang, David Andrew Kolin, Aaron Ira Weinblatt, Amar S Ranawat, Alejandro Gonzalez Della Valle, Brian Chalmers

“The Effect of Concomitant Use of Potent Anticoagulation and Anti-Inflammatories on Early Outcomes of Total Hip Arthroplasty”

Alexis Gabriel Gonzalez, Aaron Ira Weinblatt, Agnes Cororaton Jones, Stephen Lyman, Richard Hwang, Alex Anatone, Carlo Marega, Alejandro Gonzalez Della Valle, Brian Chalmers

“Cefazolin and the R-1 Side Chain: Why Your Joint Arthroplasty Patients With Cephalosporin Allergy Can Safely Be Given Cefazolin”

Josef Jolissaint, Katherine E Mallett, Andrew Thomson, Alberto V Carli, Matthew Austin

Study: Prevalence of cannabidiol use in patients undergoing sports medicine procedures on the knee, shoulder, or hip: A survey study 

Researchers set out to determine the prevalence of cannabidiol (CBD) use in patients scheduled to undergo a sports medicine procedure at HSS. “We know that managing post-operative pain with opioids carries risks, including addiction. A promising alternative gaining attention is cannabidiol, a non-intoxicating derivative of the cannabis plant that is federally legal in the United States,” said Alexandra Sideris, PhD, director of the Pain Prevention Research Center at HSS. The study was presented at the 50th Annual ASRA Meeting in Orlando, Florida on May 1. 

Reports from the National Survey on Drug Use and Health indicate that adults ages 18-35 are the most frequent self-reporters of cannabis use. “Our study aimed to shed light on the prevalence of self-medication with CBD in adults scheduled for elective sports medicine surgery on the knee, hip or shoulder, evaluating the effects in this patient population,” Dr. Sideris explained. 
Researchers emailed anonymous surveys to 470 patients between September 2024 and December 2024. Out of 159 respondents, 39% of patients reported having tried CBD. Approximately one-third indicated that they used CBD on an as-needed basis, primarily for pain or to help them sleep. Most patients used gummies, and 44% purchased them from a dispensary. One-third of the respondents indicated that CBD was either moderately or very helpful. 

“At HSS, ongoing data collection and analysis will further elucidate the perceived efficacy of cannabidiol and the potential for changes to prescription medication use with the incorporation of CBD,” Dr. Sideris noted. 

With respect to the President’s Choice award, she commented, “It is an honor to have one of the top professional organizations in the field of regional anesthesia and pain medicine highlight the collaborative work of our department's Pain Prevention Research Center. The award reflects our dedication to innovations in patient care and underscores the greater scientific community's acknowledgements of our efforts.” 

Study: Opioid Consumption During Hospitalization Across Manual, Computer- and Robotic-Assisted Total Hip Replacement

In the second study to win a President’s Choice award, HSS researchers found that patients who had robotic-assisted total hip replacement (THR) surgery needed less opioid medication during hospitalization compared to patients who had computer-assisted or manual THR. The research was presented at the ASRA meeting on May 2. 

“Effective pain management while limiting opioid consumption following total hip replacement is imperative, as it facilitates immediate postoperative function and leads to better long-term outcomes,” said Periklis Giannakis, MD, a research fellow at HSS. “While patient characteristics are important factors associated with pain control, surgical technique is also relevant. We aimed to determine if the way hip replacement was performed had an effect on the need for opioid medication after surgery.” 
Analyzing a multi-institutional database with almost 100,000 hip replacement cases, Dr. Giannakis and colleagues found that robotic-assisted hip replacement was associated with the lowest total opioid consumption during hospitalization. He noted that while the exact mechanism is unknown, reduced soft tissue trauma and a more precise robotic-assisted surgery may contribute to less acute inflammation and less pain immediately after the procedure. 

Regarding his President’s Choice award, Dr. Giannakis commented, “Receiving President’s Choice recognition is a great honor for me and a testament to the collaboration and important research that we conduct at HSS.” He notes that future collaborative studies between the Department of Anesthesiology, the Pain Prevention Research Center and the Adult Reconstruction and Joint Replacement Service at HSS will seek to obtain more specific data, such as which robotic- and computer-assisted systems were used, with the ultimate goal of optimizing postoperative pain control. 

References: 
Prevalence of cannabidiol use in patients undergoing sports medicine procedures on the knee, shoulder, or hip: A survey study 
Authors: Sophia Madjarova BA, Arjun Khorana BS, William Chan MEng, Answorth Allen MD, Riley Williams MD, Benedict Nwachukwu MD, MBA, Alexandra Sideris PhD. 
Opioid Consumption During Hospitalization Across Manual, Computer- and Robotic-Assisted Total Hip Arthroplasty 
Authors: Periklis Giannakis, MD, Juliet E. Rowe, MPH, Lisa Reisinger, MD, Alex Illescas, MPH, Alexandra Sideris, PhD, Crispiana Cozowicz, MD, Junying Wang, MPH, Sophia T. Zhuang, Jiabin Liu, MD, PHD, Lazaros Poultsides, MD, PHD, Robert G. Marx, MD, Alejandro Gonzalez Della Valle, MD, Jashvant Poeran, MD, PhD, Stavros G. Memtsoudis, MD, PhD, MBA. 
 

“We have found that robotic assistance leads to improved implant positioning, alignment and ligament balance, which enable us to better replicate the patient’s natural anatomy,” said David J. Mayman, MD, chief of the Adult Reconstruction and Joint Replacement Service at HSS. “With our vast registry of patient data and strong commitment to research, HSS is in a unique position to continue leading the evolution of robotic assistance in the operating room.”

The first study found that the use of a surgical robot during total knee replacement surgery reduced the need for manipulation under anesthesia (MUA), an outpatient procedure that may be prescribed when physical therapy (PT) after surgery becomes too painful for the patient due to joint stiffness caused by scar tissue. During the course of care, approximately 3.5% of knee replacement patients undergo MUA, according to Seth A. Jerabek, MD, hip and knee surgeon at HSS and co-author of this study, typically within 90 days of their surgery. After MUA, patients are typically better able to participate in PT and progress in their recovery.

Investigators at HSS set out to determine if the use of computer navigation or robotic-arm assistance during surgery reduced the need for MUA. Previous studies have shown that the use of either tool leads to a more precise knee replacement.

The HSS researchers conducted a retrospective chart review of 21,893 knee replacement surgeries performed between April 2008 and December 2022. They found that the use of the robotic arm or computer navigation led to a significant decrease in the number of patients who needed MUA after surgery (2.7% of patients with robotic-assisted surgery; 2.8% of patients whose surgery was performed with computer navigation; 3.7% of patients whose surgery was performed without either technology).

“These results highlight the potential benefits of incorporating technological advancements into knee replacement surgery, offering improved outcomes and reducing the need for additional interventions such as MUA,” Dr. Jerabek said.

The second study compared short-term outcomes of the anterior versus the posterior approach in robotic-assisted total hip replacement (THR) surgery. “There is no consensus on which approach has a lower risk of postoperative complications,” said Elizabeth B.  Gausden, MD, MPH, a hip and knee surgeon at HSS and principal investigator of the study. “This can often lead to confusion on the part of the patient as to which approach may be best for them. Our objective was to compare rates of dislocation, re-operation, revision and patient-reported outcome measures of each approach performed with robotic assistance.”

Dr. Gausden and colleagues identified 2,040 consecutive robotic-assisted THRs for osteoarthritis in the HSS patient registry between 2017 and 2020. A total of 497 hip replacements were performed using the anterior approach; 1,542 were performed with the posterior approach.

At mean follow-up of 18 months, the researchers found no difference in the rate of dislocation, re-operation or revision surgery between the two approaches. At early follow-up of six weeks, the anterior approach was associated with a somewhat faster functional recovery. By 3 months following the THA, there were no longer significant differences between patients who had different approaches. “The take-home message is that hip replacement has excellent outcomes with each respective approach when performed by surgeons with extensive experience in that approach,” Dr. Gausden said. “While the goal of the study was not to compare robotic THA to manual THA, it is likely that the very low incidence of instability or dislocation overall can be attributed to the use of robotic technology for planning and execution.”

"As the use of robotic assistance in joint replacement surgery becomes more common, future studies should evaluate outcomes over longer periods of time,” concluded Dr. Mayman. “As a leader in the use of this technology, HSS continues to study various robotic systems to acquire the data needed to provide the evidence-based care that will benefit our patients.”  

References:

Robotic-assisted Total Knee Arthroplasty Is Associated with Decreased Manipulation under Anesthesia Compared to Manual Approach

Authors: Cale Pagan; David J. Mayman, MD; Douglas E. Padgett, MD; Jonathan M. Vigdorchik, MD; Peter K. Sculco, MD; Seth A. Jerabek, MD; Theofilos Karasavvidis, MD (HSS).

Program Number: P153 – February 14, 2024

Comparison of Short-Term Outcomes Between Direct Anterior and Posterolateral Approach in Robotic-Assisted Total Hip Arthroplasty

Authors: Nikhil Vasireddi, MHA (Case Western); Sonia Chandi, MD; Colin Neitzke; Agnes Cororaton, MS; Jason L. Blevins, MD; Jonathan M. Vigdorchik, MD; Alexander S. McLawhorn, MD, MBA; Elizabeth B. Gausden, MD, MPH (HSS).

Program Number: e076 – February 12, 2024

Research highlights include the evaluation of artificial intelligence (AI) chatbots to provide accurate answers to medical questions about spine surgery, and two retrospective studies analyzing outcomes in both knee and hip replacement surgeries performed with robotic assistance. 

HSS Research Evaluates Whether AI Chatbots Provide Reliable Medical Information

A study co-authored by Sheeraz Qureshi, MD, MBA, co-chief of HSS Spine and colleagues identified nine frequently asked questions about cervical spine surgery, which they considered to be of particular clinical relevance. Question topics ranged from the benefits and drawbacks of different surgical approaches to side effects and recovery after surgery. The questions were inputted one at a time into ChatGPT version 3.5. Two experts in cervical spine surgery who were not involved in designing the questions rated the chatbot’s responses on accuracy, appropriateness, and readability. On average, the responses received a score of 8.1/10, with a 3.9/5 for accuracy and a 2.2/3 for appropriateness. The main drawback the reviewers noted was that ChatGPT failed to provide comprehensive responses, often omitting important factors. AI chatbots are more accurate than expected when asked to answer medical questions about spine surgery, however patients still need to use extreme caution when turning to these tools for help with medical decision-making.

New HSS Studies Highlight the Benefits of Robotic-Assisted Joint Replacement Surgery

HSS investigators presented two retrospective studies analyzing outcomes in both knee and hip replacement surgeries performed with robotic assistance.

The first study co-authored by HSS hip and knee surgeon Seth A. Jerabek, MD, and colleagues found that the use of a surgical robot during total knee replacement surgery reduced the need for manipulation under anesthesia, an outpatient procedure that may be prescribed when physical therapy after surgery becomes too painful for the patient due to joint stiffness caused by scar tissue.

The second study led by HSS hip and knee surgeon Elizabeth B.  Gausden, MD, MPH and colleagues compared short-term outcomes (e.g., rates of dislocation, re-operation, revision, and patient-reported outcome measures) of the anterior versus the posterior approach in robotic-assisted total hip replacement surgery. The investigators found that hip replacement has excellent outcomes with each respective approach when performed by surgeons with extensive experience in that approach. Additionally, it is likely that the very low incidence of instability or dislocation overall can be attributed to the use of robotic technology for planning and execution.

Treatments for a femoral neck fracture range from nonoperative management to total hip replacement. When hip replacement is the best treatment option, it can be performed with or without bone cement to secure the prosthesis.

“Femoral neck fractures are very common in the elderly and are a major cause of morbidity and mortality in this population,” explained Alexander McLawhorn, MD, a hip and knee orthopedic surgeon at HSS and study author. “Several national registry studies have demonstrated a lower risk of overall revision surgery, and specifically revision for periprosthetic fracture, with cemented femoral fixation. Despite this overwhelming data, many patients in the United States receive cementless fixation, including patients who have sustained femoral neck fractures.”

“To our knowledge, this was the first non-registry study comparing outcomes of cemented versus cementless total hip replacement for acute femoral neck fractures examining the influence of various patient factors, including bone quality,” explained Michael Kheir, MD, who presented the study at the AAOS meeting and played a leading role in the research during his fellowship at HSS. “The primary purpose was to compare complication rates between both groups, including periprosthetic fractures, aseptic revision, dislocation and mortality rates.” Dr. Kheir is currently an orthopedic surgeon specializing in hip and knee replacement at the University of Michigan.

The retrospective study analyzed 709 total hip replacement cases (199 cemented, 510 cementless) for femoral neck fractures from 2006 to 2020 at three large academic institutions: Hospital for Special Surgery, Indiana University Health and University Hospitals Cleveland Medical Center. Patient demographics, perioperative characteristics and x-rays were reviewed. The Dorr classification system, widely used to evaluate femoral bone quality, categorized patients with Dorr type A, B or C, with type C indicating the weakest bone. 

The average age of study participants was 71 years; 66.9% of patients were women. The prevalence of Dorr type bone was 21.1% type A; 66.3% type B; and 12.6% type C. Patients receiving cemented implants were older, had a lower BMI, were more often women and were more likely to have a pre-existing diagnosis of osteoporosis and Dorr C bone type.

Cementless implant stems had a higher all-cause aseptic femoral revision rate (5.1 versus 0.5%,) and periprosthetic femoral fracture rate (4.3 versus 0%). Bone classification played a major role: Each successive Dorr grade had a higher fracture rate with cementless implants (Dorr A =2.3%; Dorr B = 3.7%; Dorr C = 15.9%). There was no difference in rates of dislocation, revision due to infection or mortality rate between groups. The study found an equal distribution of male and female patients who sustained a fracture.

“While femoral fractures occurred in patients with all types of bone quality, Dorr C bone was particularly prone, with an alarmingly high fracture rate when using cementless stems,” Dr. Kheir noted. “All of the fractures requiring a revision surgery occurred in cementless cases, suggesting that cemented stems may minimize this complication, regardless of patient sex or Dorr classification.”

Authors: Alexander McLawhorn, MD, MBA; Emile-Victor Kuyl, BS, (HSS); George Ochenjele, MD, FAAOS, (UH Cleveland Medical Center); Jacob Speybroeck, MD; Julian Dilley, MD, (Indiana University Health); Michael M. Kheir, MD, (University of Michigan); R M. Meneghini, MD, FAAOS, (Indiana University Health Phys)

“Patient satisfaction related to the hospital experience following surgery is an important aspect of patient care,” said Susan M. Goodman, MD, a rheumatologist at Hospital for Special Surgery (HSS) and senior investigator. “The Press Ganey inpatient survey is commonly administered to patients to assess their satisfaction with the process of care. Our aim was to determine whether overall patient assessment scores differed by race or socioeconomic status.”

Dr. Goodman and a team of researchers reviewed the Press Ganey survey responses of more than 4,600 patients who had surgery at HSS from July 2010 to February 2012. Individuals having a primary knee or hip replacement who resided in New York, New Jersey or Connecticut were included in the study.

Researchers analyzed the data to establish an overall score, calculated as the mean of a patient’s ratings for three questions in the “Overall Assessment” section of the Press Ganey survey. The results were categorized as either “completely satisfied” (score of 100) or “not completely satisfied” (score <100).

The analysis, which included 2,516 individuals who underwent hip replacement and 2,113 who had a knee replacement, found that Black patients were more likely to indicate they were “not completely satisfied” compared to white patients in both joint replacement groups.

Dr. Goodman said that although Black patients indicated they were less satisfied with the process of care right after surgery, there was no difference in satisfaction with their joint replacement outcome. Factors such as pain and function are part of the outcome assessment, which is generally conducted two years after surgery.  

With respect to socioeconomic status, researchers considered the patient’s primary health insurance coverage. The study found that the individual’s primary payor was not associated with satisfaction in either joint replacement group.

“The study is important because we know that Black patients generally wait longer to seek treatment, presenting with worse pain and function prior to surgery, and we are trying to sort out the barriers to seeking timely care,” said Mark P. Figgie, MD, chief emeritus of the Surgical Arthritis Service at HSS and co-author of the study.

“Patient outcome measures indicate that although Black patients achieve significant improvement after surgery, it does not reach the same level as those who seek timely treatment,” he added. “Confidence in the health care system may contribute to the delay in seeking care, and this is something we need to address.”

Dr. Goodman added, “More research is needed to investigate other factors, such as perceived staff courtesy and baseline pain and function, to understand why disparities exist so we can achieve a high level of patient satisfaction for everyone.”

Authors: Anne R. Bass, MD, Emily Ying LAI, MSc, Huong Do, MA (HSS), John A. Gibbons, BA, Letitia Bradford, MD, FAAOS, FACS (Nth Dimensions), Mark P. Figgie, MD, Michael L. Parks, MD (HSS), Orett Burke, BS (Rutgers Robert Wood Johnson Medical School), Susan M. Goodman, MD (HSS).

Between 2000 and 2016, the number of total hip arthroplasty (THA) procedures performed in patients under 21 years of age increased from 347 to 551, while the total pediatric population in the United States remained stable, the researchers found.

Traditionally, most young patients undergoing THA suffer from developmental bone or joint ailments or juvenile inflammatory arthritis. However, the new study revealed that the upswing in THA procedures in young patients is not being driven by a rise in the number of children with inflammatory joint disease, suggesting that nonsurgical therapies to control these conditions are working, said Bella Mehta, MBBS, MS, MD, a rheumatologist at HSS and the senior author of the study.

“Our study shows that although THA procedures are increasingly being performed in young people, we aren’t seeing more of these patients seeking surgery for inflammatory arthritis,” Dr. Mehta said. “We’re doing a better job at treating these individuals so they don’t develop end-stage joint damage. Twenty years ago, we didn’t have access to effective pharmacologic treatments for these conditions, and now we’re using them well and helping these patients live a better life.”

“These procedures are still pretty rare in hospitals, and some surgeons might not see any young patients,” added Alex Gibbons, a research assistant in Dr. Mehta’s group and a co-author of the study. “Although some site-specific data on THAs in adolescents exist, it wasn’t known how frequently these procedures were being performed in the United States and if that frequency was growing or not.”

For the study, Dr. Mehta and her colleagues used the Kids’ Inpatient Database, a repository of information on patients under 21 years of age from approximately 4,200 hospitals in 46 states. The researchers looked for elective and non-elective primary THA procedures.

The mean age of young patients undergoing THA was just over 17 years and remained constant throughout the duration of the study. Most patients were white (55.3%) and had private insurance (56.5%). The majority (80%) of THAs were performed in urban teaching hospitals.

Mark P. Figgie, MD, chief emeritus of the Surgical Arthritis Service at HSS and a co-author of the study, said the finding that most THA procedures in young patients are performed in urban and teaching hospitals reflects a trend that is beneficial for these patients. As other studies have demonstrated in conditions like inflammatory arthritis, when hip replacements are performed by surgeons with significant experience, patients have better outcomes. “And for younger patients, the nuances require the expertise and knowledge to avoid complications and optimize outcomes,” Dr. Figgie said.

The most common diagnoses for young patients undergoing THA were osteonecrosis, osteoarthritis and juvenile idiopathic arthritis (JIA)/inflammatory arthritis, the researchers found. Over the course of the study, the frequency of THA for osteonecrosis rose from 24% to 38%, while that for arthritis fell from 27% to 4%—likely a reflection of recent improvements in medical management for the condition, they added.

Dr. Figgie noted that improvements in implant technology and materials have made the devices far more durable than they were 20 years ago. As a result, surgeons now feel more comfortable offering THA to young patients because their implants are likely to withstand the wear and tear of decades of activity.

Dr. Mehta said the findings could be of value both to clinicians and young patients, for whom, in many cases, the surgery is their first major operation. “I would use these results to say to a young person: ‘There are a lot of people who get these procedures; you’re not alone.’ I find that, especially for young patients, knowing they’re not the only ones to experience something really helps. And it’s a life-changing procedure for them.”

That’s the conclusion of a new study by researchers at Hospital for Special Surgery (HSS), in New York City, who assessed the clinical and financial effects of such initiatives for its patients undergoing hip and knee replacement surgery. Between 2014 and 2019, implementation at HSS of so-called bundled payment programs for the two procedures saved the Centers for Medicare & Medicaid Services (CMS) nearly $24 million while reducing readmissions and the utilization by patients of costly but at times medically unnecessary postoperative treatments such as intensive rehabilitation.

“Under the BPCI [Bundled Payments for Care Improvement Initiative] and CJR [Comprehensive Care for Joint Replacement] bundle programs, we were able to provide high-quality care efficiently, which in turn led to good outcomes for patients and cost savings for the payer,” said Catherine MacLean, MD, PhD, Chief Value Medical Officer at the HSS Center for the Advancement of Value in Musculoskeletal Care, and the lead author of the study.

The results were published by Dr. MacLean and other HSS colleagues in an article titled “The clinical, operational and financial components of a successful bundled payment program for lower extremity total joint replacement,” which appears in the October issue of NEJM Catalyst Innovations in Care Delivery.

In bundled payment programs, CMS provides a lump sum to physicians and/or hospitals to perform certain procedures, in this case, knee and hip replacement surgery. Doctors and hospitals that provide care at a cost lower than the target amount can keep the savings -- so long as certain quality standards are met. However, if the cost is higher, the hospitals must cover the amount above the target price.

The goal of these programs is to push health care providers to develop innovations and efficiencies that save money while preserving, or even improving, the quality of care. Savings can be used by the hospital to develop and deliver additional services that are aimed at improving quality and achieving the best use of health care resources.

As the results reported in the new study suggest, bundled payment programs can work well. However, Dr. MacLean said the success of the bundled care program at HSS -- and other medical centers that hope to achieve similar results -- hinges on access to the kind of granular data about patient outcomes that CMS provides HSS and other facilities that participate in the agency’s CJR payment model. Under the CJR, HSS is able to track the use of services and Medicare expenditures for individual patients once they leave the hospital, matching them with the hospital’s electronic medical records system. “These data allow us to better understand what happens to our patients once they are discharged and why some are readmitted,” Dr. MacLean said.

One example of an enhancement in care that was enabled by access to granular CJR data involved the identification of a significant number of hip and knee replacement patients who had excessively long stays in skilled nursing facilities after their operations. “It didn’t make sense that patients who walked into a hospital for an elective procedure were staying in a nursing home for 26 days,” Dr. MacLean said.

HSS responded to that information by implementing a health optimization program to identify and tailor care to patients with conditions known to lead to worse postoperative outcomes -- such as uncontrolled diabetes and malnutrition. HSS surgeons placed greater emphasis on pre-surgery physical therapy to ensure patients are as fit as possible prior to their operations. In addition, the hospital created clear pathways to help clinicians determine the optimal form of rehabilitation for patients upon discharge.

Although the CJR specifically covers knee and hip replacement patients, Dr. MacLean said the lessons learned from the data have led to wide-ranging benefits. “The programs that we have put in place as a result of our analysis of CJR data have had a spillover effect on how we manage our entire population. As a proof point, our Medicare spending per beneficiary improved from the 62^nd to the 16^th percentile nationally during the study period,” she said.

Dr. MacLean’s group is now working on an analysis of the effectiveness and efficiencies of HSS@Home, a telemedicine physical therapy program launched in 2018, before the COVID-19 pandemic.

More than one million Americans undergo knee, hip, elbow and shoulder replacements annually. About one in 75 patients, less than two percent, develop bacterial infections around the joint implants, called prosthetic joint infections. Though the numbers of affected patients are small, the consequences of prosthetic joint infection can be severe.

HSS performs more joint replacement surgeries than any other hospital in the world—a total of 11,000 annually. “Our infection rate is significantly below the national average, but prosthetic joint infections are devastating for affected patients,” says Mathias P. Bostrom, MD, chief of the Adult Reconstruction and Joint Replacement Service at HSS. “Many do not return to the full potential of their original joint replacement.”

It is essential to identify the bacteria causing an infection so that a patient receives the right antibiotic. Since current blood tests only report levels of inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, surgeons typically collect a fluid sample from the joint via needle aspiration. However, standard lab test results take at least three days and fail to identify the infectious pathogen in 15 to 20 percent of cases due to the challenges of growing bacteria in culture.

When bacterial identification is unknown, surgeons withhold antibiotics until they obtain tissue samples during the implant removal surgery. The removal procedure involves taking out the contaminated implant hardware and infected soft tissue. Surgeons insert a temporary spacer containing high-dose antibiotics, and they may also place antibiotic beads into the joint. Patients are also treated with high-dose intravenous antibiotics. It takes about six weeks to three months for an infection to clear before patients can undergo another operation to remove the spacer and receive a new permanent joint implant.

The idea for finding a new way to improve the diagnostic approach for patients with prosthetic joint infections began with principal investigator Laura Donlin, PhD, co-director of the Derfner Foundation Precision Medicine Laboratory and a member of the arthritis and tissue degeneration program of the HSS Research Institute. She attended a talk by a professor of bioengineering at Stanford University who had analyzed DNA shed from transplanted organs circulating in blood, called cell-free DNA, as an early detection system for transplant rejection. But through genomic sequencing of circulating cell-free DNA, he had also found increased levels of viral cell-free DNA in some patients’ blood indicating they had developed viral infections while taking immunosuppressant medications.

Dr. Donlin wondered if it would be possible to use the same approach to identify bacteria in patients with prosthetic joint infections. “It was unknown whether bacterial DNA from localized tissue infections around joint implants would be detectable in blood,” says Dr. Donlin. “It’s a challenging environment with many other bits of circulating microbial DNA from skin flora, the gut microbiome and other infections.”

For their proof-of-concept study, Dr. Donlin together with orthopedic surgeons including Michael P. Cross, MD and Dr. Bostrom and colleagues at HSS and Weill Cornell Medicine collected blood samples from 53 patients with known hip or knee prosthetic joint infections beginning in 2018. Karius, a genomic insights company based in Redwood City, California, sequenced blood samples collected from patients before treatment for infection and at the time of reimplantation surgery. They compared microbial cell-free DNA in the blood samples to their proprietary database of more than 1,300 known microbial genomes. The HSS investigators compared sequencing findings with results from standard tissue cultures.

Among surgical tissue samples from these 53 patients, traditional lab cultures identified the bacterial species in 35 cases and the bacterial genus in 11 cases, an overall detection rate of 87 percent. Microbial cell-free DNA sequencing identified the bacterial species in 23 cases in agreement with standard culture results. The new approach also identified the bacterial species in eight cases where cultures identified the bacterial genus only and four cases where cultures failed to determine the presence of bacteria.

On its own, microbial cell-free DNA sequencing pinpointed the bacterial species in 66 percent of samples. However, as an addition to standard culture results, it increased pathogen detection from 87 to 94 percent of samples. Microbial cell-free DNA sequencing was three days faster reporting the bacterial species for cases where culture results had only identified the bacterial family.

Analyses of follow-up blood samples after joint removal surgery and treatment with antibiotics showed undetectable or reduced bacteria levels. “For most patients, we saw microbial cell-free DNA levels drop below detection, indicating the infections had most likely cleared,” says Dr. Donlin. “But there were some cases with lower yet detectable levels after six weeks of antibiotic treatment. Considering that cell-free DNA lives in the bloodstream for only a few minutes, that meant these patients still had an ongoing infection and might require modification to their antibiotic treatment plan.”

“An indication that there is an infection, at least to the genus level for samples that fail to show results in standard cultures, will be beneficial for diagnosing and treating patients earlier for improved outcomes,” says Dr. Bostrom. “As a monitoring tool, microbial cell-free DNA sequencing has the potential to provide important information on the right time to change or stop antibiotics and for reimplantation surgery.”

Dr. Donlin and colleagues are improving the sensitivity and specificity of the new diagnostic method in collaboration with Karius and planning a multicenter study to test it on a larger scale. “In the future, we hope microbial cell-free DNA sequencing will prove to be a useful tool for detecting joint infections more quickly than is currently possible,” Dr. Donlin says. “We’re very excited that our innovation may one day translate to improved outcomes for patients.”

The study was supported by funding provided by the Price Family Foundation, the Stavros Niarchos Foundation Complex Joint Reconstruction Center at HSS, the Feldstein Medical Foundation, the Carson Family Charitable Trust, the Ambrose Monell Foundation, the HSS Research Institute’s David Z. Rosensweig Center for Genomics Research, the National Institutes of Health, the Bill and Melinda Gates Foundation, the Leukemia & Lymphoma Society and the National Science Foundation.