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Machine-Learning Tool Identified Predictive Factors Associated with Worse Patient Outcomes After Arthroscopic Hip Surgery for Femoroacetabular Impingement

A machine-learning algorithm developed by an orthopedic surgeon at Hospital for Special Surgery (HSS) and his colleagues identified predictive factors associated with worse outcomes for patients with femoroacetabular impingement (FAI) of the hip who had arthroscopic surgery to treat it. FAI is a condition in which the ball and socket of the hip joint do not fit together properly and can ultimately cause pain and the need for a surgical repair.

According to a paper published on January 31 in the American Journal of Sports Medicine, the factors that significantly predicted worse patient outcomes were anxiety and depression, duration of symptoms for more than two years before surgery, a high preoperative score on patient-reported outcome surveys and, surprisingly, receiving preoperative steroid injections.

“These findings are important from several perspectives. First of all, they demonstrate the value of integrating a machine-learning tool into clinical practice,” says first author Benedict Nwachukwu MD, MBA, a sports medicine surgeon and co-director of clinical research for the Sports Medicine Institute at HSS in New York City. “From a clinical perspective, our results reinforce that we should be screening for anxiety and depression. The symptom duration finding should encourage more payers and insurance companies to cover hip surgery for patients sooner, rather than keep them in prolonged conservative treatment. Finally, the risk associated with the use of preoperative injections is a novel finding that has not been reported very often in the literature.”

Dr. Nwachukwu helped design the study and developed the machine-learning algorithm in collaboration with a data scientist at PatientIQ, the company that provided the data analysis platform. He collaborated with colleagues at Wake Forest Baptist Health in Winston-Salem, North Carolina, and at Rush University Medical Center in Chicago, Illinois. Senior investigator Shane J. Nho, MD, MS, hip arthroscopy specialist at Midwest Orthopaedics at Rush, performed the hip arthroscopy surgeries and provided the patient data. Dr. Nho was a resident in orthopedic surgery at HSS from 2003 to 2008.

Dr. Nwachukwu and colleagues built the machine-learning algorithm using electronic health record data for 898 patients with FAI who had hip arthroscopic surgery between January 2012 and July 2016 at Rush University Medical Center. All patients had completed three patient-reported outcome surveys before surgery and again two years after surgery: the Hip Outcome Score-Activities of Daily Living Subscale (HOS-ADL) ; the Hip Outcome Score-Sports Subscale (HOS-SS); and the modified Harris Hip Score (mHHS). These subjective measures collect patients’ reports on their abilities to perform daily activities and sports activities and their overall hip condition, respectively.

The researchers determined the factors associated with achieving or not achieving the minimal clinically important difference in these patient-reported outcome measures and then analyzed the large dataset of patient information. In addition to identifying factors that predicted worse patient outcomes, the investigators found two variables that predicted achieving better results: running, at least at the recreational level, and being female.

This study is one of few reporting on the negative impact of preoperative steroid injections on patient-reported outcomes after orthopedic hip surgery. Patient response to steroid injections is a common diagnostic approach for confirming the hip joint as the location of the pain. Some insurance companies will not approve surgery for FAI unless a patient has had a diagnostic steroid injection first.

“Worse postoperative outcomes after the preoperative use of steroid injections may be due to poor healing of the labral tissue after exposure to steroid,” Dr. Nwachukwu says. “Our finding suggests that surgeons should consider the use of steroid injections judiciously. They have a role to play but using a purely anesthetic injection for diagnostic purposes may be a better option.”

About HSS

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.