No Increased Risk of Complications for TJA in an Ambulatory Surgery Setting

    The typical in-hospital length of stay after total hip and total knee arthroplasty procedures has decreased over the last decade from about 4 days to less than 2 days. In some cases, patients are being discharged the same day as surgery.

    “It’s early in the trend, but there is a massive shift taking place toward more ambulatory hip and knee replacement surgeries that allow that patients go home on the same day of their operations,” said Michael P. Ast, MD, from Hospital for Special Surgery.

    “Currently, about 5% of total hip and knee replacement surgeries are performed on an ambulatory basis, but that figure is expected to rise to about 50% in the next 5 years.”

    Factors driving the trend toward ambulatory total joint arthroplasty include improvements in surgical techniques, implant devices, and pain control, as well as the potential for significantly reduced healthcare system costs.

    “But before the trend is adopted on a more widespread basis, we need to ensure that the risks of complications for patients do not increase,” Dr. Ast said.

    Dr. Ast and colleagues, including Alvin C. Ong, MD, at The Rothman Orthopedic Institute, recently conducted a study to compare patient outcomes and costs for in-patient versus outpatient total hip arthroplasty (THA) and total knee arthroplasty (TKA). The study was presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons.

    The researchers found no increased risk of complications or readmissions for patients who were discharged from the ambulatory surgery center on the same day as surgery compared with patients who had the same procedures and stayed in the hospital.

    Dr. Ast performed the ambulatory procedures at a community-based ambulatory surgery center and Dr. Ong performed the in-patient surgeries at a university medical center. They created a 5-year prospective registry of all patients who underwent ambulatory THA or TKA beginning in 2014. The 126 patients in the ambulatory group were matched 1:1 to 126 patients in the in-patient group based on surgical procedure, age, sex, body mass index, and health assessments. In each group, 77 patients underwent THA and 49 underwent TKA.

    The average length of stay was 8:09 hours for the ambulatory group compared with 23:24 hours for the in-patient group. Overall, the 90-day complication rate was low, with no meaningful difference between groups: 2.4% for the ambulatory group and 3.9% for the in-patient group. There was also no significant difference between groups for 90-day readmission rates.

    The average cost per patient was $11,677 for the ambulatory group and $19,361 for the in-patient group. Costs included all costs associated with the surgery, such as the costs of the implant, staffing, and medications, and immediate postoperative care.

    “I was very pleased to see there were no increased risks in complications or readmissions for ambulatory patients,” Dr. Ast said. “But I didn’t expect the cost difference would be so large – 40% less for the ambulatory group than for the in-patient group.”

    In partnership with his colleagues, Dr. Ast has helped to create an outpatient joint program at Hospital for Special Surgery. He said that patients who are relatively healthy, have support at home after surgery, and have few risk factors such heart disease, a history of blood clots, or untreated sleep apnea are the best candidates for ambulatory surgery.

    By the year 2030, there will be an estimated 635,000 hip replacements and 1.28 million knee replacements every year. “If up to half of those are ambulatory procedures, at a savings of 40%, the healthcare system will save billions,” Dr. Ast said. “But patient outcomes are still our number one priority.”


    Ast M, Davis D, Carroll K, Ong A. No Increased Risk of 90-Day Complication or Readmission, as Well as Decreased Cost, with Total Joint Replacement in a Private, Community-Based Ambulatory Surgery Center (Poster P0593). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.