Study identifies risk factors for readmissions after shoulder replacement surgeries

Shoulder replacement is the third most common joint-replacement surgery in the U.S. and is likely to become more common as the population ages, according to Penn State researchers. Though most patients go home on the same day as their surgery, those with greater health risks or serious injuries are admitted to the hospital for shoulder replacement. Patients who experience complications like infection or sepsis sometimes need to be readmitted to the hospital for treatment at a later date.

In a study published in the Journal of Bone & Joint Surgery Open Access, an interdisciplinary team of Penn State researchers identified the demographic and medical factors related to increased readmission rates after inpatient shoulder replacement surgeries in Pennsylvania. The researchers found that risk factors for readmission included the urgency of initial admission to the hospital, the number of other health problems a patient experienced, where a patient was housed following discharge from the hospital and their insurance type. The results could be used to improve both patient outcomes and the efficiency of the healthcare system, according to the researchers. 

Shoulder replacement is a very common and very successful surgery. But readmission is costly and difficult for patients, so each readmission that can be prevented is worthwhile. We examined years of data from the highest-risk shoulder-replacements in Pennsylvania - inpatient surgeries - to identify what readmitted patients have in common."

Christopher Hollenbeak, senior author, professor and head of the Department of Health Policy and Administration, Penn State

Using data from the Pennsylvania Health Care Cost Containment Council, the researchers reviewed 14,333 cases of inpatient shoulder replacement surgery - known medically as total shoulder arthroscopy - in Pennsylvania between 2010 and 2018. Due to the statewide nature of the dataset, the researchers were able to include patients who received a shoulder replacement in one hospital but were readmitted to a different facility in the commonwealth. Every patient who was readmitted within 30 days was included in the study, regardless of their reason for readmission. 

Of the more than 14,000 patients who underwent inpatient shoulder replacement surgery in Pennsylvania during the study, 469 were readmitted within 30 days. Patients who were insured by Medicare were 96% more likely to be readmitted than those with private insurance - almost doubling their odds. The researchers also found that people who were discharged from the hospital to a skilled nursing facility were 61% more likely to require readmission, while those discharged with home health care were 28% more likely to return within the month. 

The risk factors identified in the study were not the root causes of the readmissions, according to the researchers. For example, they noted that people insured by Medicare received the same surgery as people who had private insurance, yet they were almost twice as likely to require additional hospitalization within 30 days.

The researchers identified other risk factors for readmission as well. Patients admitted for urgent shoulder surgery - rather than a scheduled procedure - were 65% more likely to be readmitted within 30 days. Those who received a reverse shoulder replacement - where the socket is affixed to the humerus, and the ball is on the shoulder joint - were 36% more likely to be readmitted. Patients who had one or two other significant medical conditions - like heart disease or diabetes - were 52% more likely to be readmitted, while those with three or more such conditions were 148% more likely to need to return to the hospital. 

These results may be interrelated, according to April Armstrong, C. McCollister Evarts Professor and Chair in the Department of Orthopaedics and Therapy Services at Penn State College of Medicine and co-author of the study. For example, sicker people - those with multiple other conditions - often have more complications in recovery. Additionally, reverse shoulder replacements are often performed on patients with a fractured humerus, which means those surgeries are often more urgent.

While the risk of readmission after shoulder surgery is driven by factors beyond the control of patients and hospitals, the researchers said the factors identified in this study point to ways to improve patient outcomes and reduce readmissions. 

"A multidisciplinary approach to discharge planning and care for these patients is extremely important," Armstrong said. "By understanding the challenges leading to readmission, we can better educate caregivers, patients and families. We can also set clear expectations for managing medications, scheduling postoperative follow-up care and addressing factors like an individual's access to care." 

In addition to more robust discharge planning, the researchers suggested that health care systems could provide additional training for home health workers and staff at skilled nursing facilities. When surgical readmission rates for Medicare patients are too high, hospitals can be penalized and receive reduced payments for those surgeries, so facilities have a financial incentive to provide trainings that would reduce readmissions, the researchers said. 

"If you could supplement patient visits with observations of the surgical wound site and check for signs of infections of bleeding, patients may be able to get the treatment they need without readmission," Hollenbeak said. "Each readmission is very expensive, so training would be financially worthwhile. More importantly, it's a better outcome for patients." 

Brian Johnson, a Schreyer honors student who earned a bachelor's degree in business from Penn State in 2025, contributed substantially to this research. Johnson, first author of the paper, initiated the study because he was interested in becoming a physician, Hollenbeak said. Today, Johnson is a student at the Penn State College of Medicine.